Examples: refactor all examples with a MainLoopStep() function, to facilitate use with Emscripten. (#2492, #3699)

Aligned all examples.

docs/CHANGELOG.txt

@@ -95,6 +95,10 @@ All changes:
   Latest Emscripten seems to emit correct values.
 - Backend: WebGPU: Fix building for latest WebGPU specs (remove implicit layout generation).
   (#6117, #4116, #3632) [@tonygrue, @bfierz]
+- Examples: refactord all examples to use a "MainLoopStep()" function. This is in order
+  to be able to trivially make some compile with Emscripten. (#2492, #3699)
+  While not all examples are expected to compile on Emscripten, we try to keep all of them
+  as close as possible to each others.
 - Examples: Win32: Fixed examples using RegisterClassW() since 1.89 to also call
   DefWindowProcW() instead of DefWindowProc() so that title text are correctly converted
   when application is compiled without /DUNICODE. (#5725, #5961, #5975) [@markreidvfx]

examples/example_allegro5/main.cpp

@@ -16,6 +16,10 @@
 #include "imgui.h"
 #include "imgui_impl_allegro5.h"
 
+// Forward declarations of helper functions
+bool MainLoopStep(ALLEGRO_DISPLAY* display, ALLEGRO_EVENT_QUEUE* queue);
+
+// Main code
 int main(int, char**)
 {
     // Setup Allegro
@@ -23,6 +27,8 @@ int main(int, char**)
     al_install_keyboard();
     al_install_mouse();
     al_init_primitives_addon();
+
+    // Create window with graphics context and event queue
     al_set_new_display_flags(ALLEGRO_RESIZABLE);
     ALLEGRO_DISPLAY* display = al_create_display(1280, 720);
     al_set_window_title(display, "Dear ImGui Allegro 5 example");
@@ -60,86 +66,98 @@ int main(int, char**)
     //ImFont* font = io.Fonts->AddFontFromFileTTF("c:\\Windows\\Fonts\\ArialUni.ttf", 18.0f, NULL, io.Fonts->GetGlyphRangesJapanese());
     //IM_ASSERT(font != NULL);
 
-    bool show_demo_window = true;
-    bool show_another_window = false;
-    ImVec4 clear_color = ImVec4(0.45f, 0.55f, 0.60f, 1.00f);
-
     // Main loop
-    bool running = true;
-    while (running)
+    while (true)
+    {
+        if (!MainLoopStep(display, queue))
+            break;
+    }
+
+    // Cleanup
+    ImGui_ImplAllegro5_Shutdown();
+    ImGui::DestroyContext();
+    al_destroy_event_queue(queue);
+    al_destroy_display(display);
+
+    return 0;
+}
+
+bool MainLoopStep(ALLEGRO_DISPLAY* display, ALLEGRO_EVENT_QUEUE* queue)
+{
+    // Poll and handle events (inputs, window resize, etc.)
+    // You can read the io.WantCaptureMouse, io.WantCaptureKeyboard flags to tell if dear imgui wants to use your inputs.
+    // - When io.WantCaptureMouse is true, do not dispatch mouse input data to your main application, or clear/overwrite your copy of the mouse data.
+    // - When io.WantCaptureKeyboard is true, do not dispatch keyboard input data to your main application, or clear/overwrite your copy of the keyboard data.
+    // Generally you may always pass all inputs to dear imgui, and hide them from your application based on those two flags.
+    bool done = false;
+    ALLEGRO_EVENT ev;
+    while (al_get_next_event(queue, &ev))
     {
-        // Poll and handle events (inputs, window resize, etc.)
-        // You can read the io.WantCaptureMouse, io.WantCaptureKeyboard flags to tell if dear imgui wants to use your inputs.
-        // - When io.WantCaptureMouse is true, do not dispatch mouse input data to your main application, or clear/overwrite your copy of the mouse data.
-        // - When io.WantCaptureKeyboard is true, do not dispatch keyboard input data to your main application, or clear/overwrite your copy of the keyboard data.
-        // Generally you may always pass all inputs to dear imgui, and hide them from your application based on those two flags.
-        ALLEGRO_EVENT ev;
-        while (al_get_next_event(queue, &ev))
+        ImGui_ImplAllegro5_ProcessEvent(&ev);
+        if (ev.type == ALLEGRO_EVENT_DISPLAY_CLOSE)
+            done = true;
+        if (ev.type == ALLEGRO_EVENT_DISPLAY_RESIZE)
         {
-            ImGui_ImplAllegro5_ProcessEvent(&ev);
-            if (ev.type == ALLEGRO_EVENT_DISPLAY_CLOSE)
-                running = false;
-            if (ev.type == ALLEGRO_EVENT_DISPLAY_RESIZE)
-            {
-                ImGui_ImplAllegro5_InvalidateDeviceObjects();
-                al_acknowledge_resize(display);
-                ImGui_ImplAllegro5_CreateDeviceObjects();
-            }
+            ImGui_ImplAllegro5_InvalidateDeviceObjects();
+            al_acknowledge_resize(display);
+            ImGui_ImplAllegro5_CreateDeviceObjects();
         }
+    }
+    if (done)
+        return false;
 
-        // Start the Dear ImGui frame
-        ImGui_ImplAllegro5_NewFrame();
-        ImGui::NewFrame();
+    // Start the Dear ImGui frame
+    ImGui_ImplAllegro5_NewFrame();
+    ImGui::NewFrame();
 
-        // 1. Show the big demo window (Most of the sample code is in ImGui::ShowDemoWindow()! You can browse its code to learn more about Dear ImGui!).
-        if (show_demo_window)
-            ImGui::ShowDemoWindow(&show_demo_window);
+    // Our state
+    // (we use static, which essentially makes the variable globals, as a convenience to keep the example code easy to follow)
+    static bool show_demo_window = true;
+    static bool show_another_window = false;
+    static ImVec4 clear_color = ImVec4(0.45f, 0.55f, 0.60f, 1.00f);
 
-        // 2. Show a simple window that we create ourselves. We use a Begin/End pair to create a named window.
-        {
-            static float f = 0.0f;
-            static int counter = 0;
+    // 1. Show the big demo window (Most of the sample code is in ImGui::ShowDemoWindow()! You can browse its code to learn more about Dear ImGui!).
+    if (show_demo_window)
+        ImGui::ShowDemoWindow(&show_demo_window);
 
-            ImGui::Begin("Hello, world!");                          // Create a window called "Hello, world!" and append into it.
+    // 2. Show a simple window that we create ourselves. We use a Begin/End pair to create a named window.
+    {
+        static float f = 0.0f;
+        static int counter = 0;
 
-            ImGui::Text("This is some useful text.");               // Display some text (you can use a format strings too)
-            ImGui::Checkbox("Demo Window", &show_demo_window);      // Edit bools storing our window open/close state
-            ImGui::Checkbox("Another Window", &show_another_window);
+        ImGui::Begin("Hello, world!");                          // Create a window called "Hello, world!" and append into it.
 
-            ImGui::SliderFloat("float", &f, 0.0f, 1.0f);            // Edit 1 float using a slider from 0.0f to 1.0f
-            ImGui::ColorEdit3("clear color", (float*)&clear_color); // Edit 3 floats representing a color
+        ImGui::Text("This is some useful text.");               // Display some text (you can use a format strings too)
+        ImGui::Checkbox("Demo Window", &show_demo_window);      // Edit bools storing our window open/close state
+        ImGui::Checkbox("Another Window", &show_another_window);
 
-            if (ImGui::Button("Button"))                            // Buttons return true when clicked (most widgets return true when edited/activated)
-                counter++;
-            ImGui::SameLine();
-            ImGui::Text("counter = %d", counter);
+        ImGui::SliderFloat("float", &f, 0.0f, 1.0f);            // Edit 1 float using a slider from 0.0f to 1.0f
+        ImGui::ColorEdit3("clear color", (float*)&clear_color); // Edit 3 floats representing a color
 
-            ImGui::Text("Application average %.3f ms/frame (%.1f FPS)", 1000.0f / ImGui::GetIO().Framerate, ImGui::GetIO().Framerate);
-            ImGui::End();
-        }
+        if (ImGui::Button("Button"))                            // Buttons return true when clicked (most widgets return true when edited/activated)
+            counter++;
+        ImGui::SameLine();
+        ImGui::Text("counter = %d", counter);
 
-        // 3. Show another simple window.
-        if (show_another_window)
-        {
-            ImGui::Begin("Another Window", &show_another_window);   // Pass a pointer to our bool variable (the window will have a closing button that will clear the bool when clicked)
-            ImGui::Text("Hello from another window!");
-            if (ImGui::Button("Close Me"))
-                show_another_window = false;
-            ImGui::End();
-        }
+        ImGui::Text("Application average %.3f ms/frame (%.1f FPS)", 1000.0f / ImGui::GetIO().Framerate, ImGui::GetIO().Framerate);
+        ImGui::End();
+    }
 
-        // Rendering
-        ImGui::Render();
-        al_clear_to_color(al_map_rgba_f(clear_color.x * clear_color.w, clear_color.y * clear_color.w, clear_color.z * clear_color.w, clear_color.w));
-        ImGui_ImplAllegro5_RenderDrawData(ImGui::GetDrawData());
-        al_flip_display();
+    // 3. Show another simple window.
+    if (show_another_window)
+    {
+        ImGui::Begin("Another Window", &show_another_window);   // Pass a pointer to our bool variable (the window will have a closing button that will clear the bool when clicked)
+        ImGui::Text("Hello from another window!");
+        if (ImGui::Button("Close Me"))
+            show_another_window = false;
+        ImGui::End();
     }
 
-    // Cleanup
-    ImGui_ImplAllegro5_Shutdown();
-    ImGui::DestroyContext();
-    al_destroy_event_queue(queue);
-    al_destroy_display(display);
+    // Rendering
+    ImGui::Render();
+    al_clear_to_color(al_map_rgba_f(clear_color.x * clear_color.w, clear_color.y * clear_color.w, clear_color.z * clear_color.w, clear_color.w));
+    ImGui_ImplAllegro5_RenderDrawData(ImGui::GetDrawData());
+    al_flip_display();
 
-    return 0;
+    return true;
 }

examples/example_android_opengl3/main.cpp

@@ -21,11 +21,72 @@ static char                 g_LogTag[] = "ImGuiExample";
 static std::string          g_IniFilename = "";
 
 // Forward declarations of helper functions
+static void Init(struct android_app* app);
+static void Shutdown();
+static void MainLoopStep();
 static int ShowSoftKeyboardInput();
 static int PollUnicodeChars();
 static int GetAssetData(const char* filename, void** out_data);
 
-void init(struct android_app* app)
+// Main code
+static void handleAppCmd(struct android_app* app, int32_t appCmd)
+{
+    switch (appCmd)
+    {
+    case APP_CMD_SAVE_STATE:
+        break;
+    case APP_CMD_INIT_WINDOW:
+        Init(app);
+        break;
+    case APP_CMD_TERM_WINDOW:
+        Shutdown();
+        break;
+    case APP_CMD_GAINED_FOCUS:
+    case APP_CMD_LOST_FOCUS:
+        break;
+    }
+}
+
+static int32_t handleInputEvent(struct android_app* app, AInputEvent* inputEvent)
+{
+    return ImGui_ImplAndroid_HandleInputEvent(inputEvent);
+}
+
+void android_main(struct android_app* app)
+{
+    app->onAppCmd = handleAppCmd;
+    app->onInputEvent = handleInputEvent;
+
+    while (true)
+    {
+        int out_events;
+        struct android_poll_source* out_data;
+
+        // Poll all events. If the app is not visible, this loop blocks until g_Initialized == true.
+        while (ALooper_pollAll(g_Initialized ? 0 : -1, NULL, &out_events, (void**)&out_data) >= 0)
+        {
+            // Process one event
+            if (out_data != NULL)
+                out_data->process(app, out_data);
+
+            // Exit the app by returning from within the infinite loop
+            if (app->destroyRequested != 0)
+            {
+                // shutdown() should have been called already while processing the
+                // app command APP_CMD_TERM_WINDOW. But we play save here
+                if (!g_Initialized)
+                    Shutdown();
+
+                return;
+            }
+        }
+
+        // Initiate a new frame
+        MainLoopStep();
+    }
+}
+
+void Init(struct android_app* app)
 {
     if (g_Initialized)
         return;
@@ -125,13 +186,14 @@ void init(struct android_app* app)
     g_Initialized = true;
 }
 
-void tick()
+void MainLoopStep()
 {
     ImGuiIO& io = ImGui::GetIO();
     if (g_EglDisplay == EGL_NO_DISPLAY)
         return;
 
     // Our state
+    // (we use static, which essentially makes the variable globals, as a convenience to keep the example code easy to follow)
     static bool show_demo_window = true;
     static bool show_another_window = false;
     static ImVec4 clear_color = ImVec4(0.45f, 0.55f, 0.60f, 1.00f);
@@ -197,7 +259,7 @@ void tick()
     eglSwapBuffers(g_EglDisplay, g_EglSurface);
 }
 
-void shutdown()
+void Shutdown()
 {
     if (!g_Initialized)
         return;
@@ -228,63 +290,7 @@ void shutdown()
     g_Initialized = false;
 }
 
-static void handleAppCmd(struct android_app* app, int32_t appCmd)
-{
-    switch (appCmd)
-    {
-    case APP_CMD_SAVE_STATE:
-        break;
-    case APP_CMD_INIT_WINDOW:
-        init(app);
-        break;
-    case APP_CMD_TERM_WINDOW:
-        shutdown();
-        break;
-    case APP_CMD_GAINED_FOCUS:
-        break;
-    case APP_CMD_LOST_FOCUS:
-        break;
-    }
-}
-
-static int32_t handleInputEvent(struct android_app* app, AInputEvent* inputEvent)
-{
-    return ImGui_ImplAndroid_HandleInputEvent(inputEvent);
-}
-
-void android_main(struct android_app* app)
-{
-    app->onAppCmd = handleAppCmd;
-    app->onInputEvent = handleInputEvent;
-
-    while (true)
-    {
-        int out_events;
-        struct android_poll_source* out_data;
-
-        // Poll all events. If the app is not visible, this loop blocks until g_Initialized == true.
-        while (ALooper_pollAll(g_Initialized ? 0 : -1, NULL, &out_events, (void**)&out_data) >= 0)
-        {
-            // Process one event
-            if (out_data != NULL)
-                out_data->process(app, out_data);
-
-            // Exit the app by returning from within the infinite loop
-            if (app->destroyRequested != 0)
-            {
-                // shutdown() should have been called already while processing the
-                // app command APP_CMD_TERM_WINDOW. But we play save here
-                if (!g_Initialized)
-                    shutdown();
-
-                return;
-            }
-        }
-
-        // Initiate a new frame
-        tick();
-    }
-}
+// Helper functions
 
 // Unfortunately, there is no way to show the on-screen input from native code.
 // Therefore, we call ShowSoftKeyboardInput() of the main activity implemented in MainActivity.kt via JNI.

examples/example_emscripten_wgpu/main.cpp

@@ -21,17 +21,13 @@ static WGPUSwapChain wgpu_swap_chain = NULL;
 static int           wgpu_swap_chain_width = 0;
 static int           wgpu_swap_chain_height = 0;
 
-// States tracked across render frames
-static bool show_demo_window = true;
-static bool show_another_window = false;
-static ImVec4 clear_color = ImVec4(0.45f, 0.55f, 0.60f, 1.00f);
-
 // Forward declarations
-static bool init_wgpu();
-static void main_loop(void* window);
+static void MainLoopStep(void* window);
+static bool InitWGPU();
 static void print_glfw_error(int error, const char* description);
 static void print_wgpu_error(WGPUErrorType error_type, const char* message, void*);
 
+// Main code
 int main(int, char**)
 {
     glfwSetErrorCallback(print_glfw_error);
@@ -39,9 +35,8 @@ int main(int, char**)
         return 1;
 
     // Make sure GLFW does not initialize any graphics context.
-    // This needs to be done explicitly later
+    // This needs to be done explicitly later.
     glfwWindowHint(GLFW_CLIENT_API, GLFW_NO_API);
-
     GLFWwindow* window = glfwCreateWindow(1280, 720, "Dear ImGui GLFW+WebGPU example", NULL, NULL);
     if (!window)
     {
@@ -50,7 +45,7 @@ int main(int, char**)
     }
 
     // Initialize the WebGPU environment
-    if (!init_wgpu())
+    if (!InitWGPU())
     {
         if (window)
             glfwDestroyWindow(window);
@@ -101,12 +96,12 @@ int main(int, char**)
     // This function will directly return and exit the main function.
     // Make sure that no required objects get cleaned up.
     // This way we can use the browsers 'requestAnimationFrame' to control the rendering.
-    emscripten_set_main_loop_arg(main_loop, window, 0, false);
+    emscripten_set_main_loop_arg(MainLoopStep, window, 0, false);
 
     return 0;
 }
 
-static bool init_wgpu()
+static bool InitWGPU()
 {
     wgpu_device = emscripten_webgpu_get_device();
     if (!wgpu_device)
@@ -130,24 +125,21 @@ static bool init_wgpu()
     return true;
 }
 
-static void main_loop(void* window)
+static void MainLoopStep(void* window)
 {
     glfwPollEvents();
 
     int width, height;
-    glfwGetFramebufferSize((GLFWwindow*) window, &width, &height);
+    glfwGetFramebufferSize((GLFWwindow*)window, &width, &height);
 
     // React to changes in screen size
     if (width != wgpu_swap_chain_width && height != wgpu_swap_chain_height)
     {
         ImGui_ImplWGPU_InvalidateDeviceObjects();
-
         if (wgpu_swap_chain)
             wgpuSwapChainRelease(wgpu_swap_chain);
-
         wgpu_swap_chain_width = width;
         wgpu_swap_chain_height = height;
-
         WGPUSwapChainDescriptor swap_chain_desc = {};
         swap_chain_desc.usage = WGPUTextureUsage_RenderAttachment;
         swap_chain_desc.format = WGPUTextureFormat_RGBA8Unorm;
@@ -155,7 +147,6 @@ static void main_loop(void* window)
         swap_chain_desc.height = height;
         swap_chain_desc.presentMode = WGPUPresentMode_Fifo;
         wgpu_swap_chain = wgpuDeviceCreateSwapChain(wgpu_device, wgpu_surface, &swap_chain_desc);
-
         ImGui_ImplWGPU_CreateDeviceObjects();
     }
 
@@ -164,6 +155,12 @@ static void main_loop(void* window)
     ImGui_ImplGlfw_NewFrame();
     ImGui::NewFrame();
 
+    // Our state
+    // (we use static, which essentially makes the variable globals, as a convenience to keep the example code easy to follow)
+    static bool show_demo_window = true;
+    static bool show_another_window = false;
+    static ImVec4 clear_color = ImVec4(0.45f, 0.55f, 0.60f, 1.00f);
+
     // 1. Show the big demo window (Most of the sample code is in ImGui::ShowDemoWindow()! You can browse its code to learn more about Dear ImGui!).
     if (show_demo_window)
         ImGui::ShowDemoWindow(&show_demo_window);
@@ -229,7 +226,7 @@ static void main_loop(void* window)
 
 static void print_glfw_error(int error, const char* description)
 {
-    printf("Glfw Error %d: %s\n", error, description);
+    printf("GLFW Error %d: %s\n", error, description);
 }
 
 static void print_wgpu_error(WGPUErrorType error_type, const char* message, void*)

examples/example_glfw_opengl2/main.cpp

@@ -23,22 +23,30 @@
 #pragma comment(lib, "legacy_stdio_definitions")
 #endif
 
+// Data
+static GLFWwindow* g_AppWindow = NULL;
+
+// Forward declarations of helper functions
+void MainLoopStep();
 static void glfw_error_callback(int error, const char* description)
 {
-    fprintf(stderr, "Glfw Error %d: %s\n", error, description);
+    fprintf(stderr, "GLFW Error %d: %s\n", error, description);
 }
 
+// Main code
 int main(int, char**)
 {
-    // Setup window
     glfwSetErrorCallback(glfw_error_callback);
     if (!glfwInit())
         return 1;
+
+    // Create window with graphics context
     GLFWwindow* window = glfwCreateWindow(1280, 720, "Dear ImGui GLFW+OpenGL2 example", NULL, NULL);
     if (window == NULL)
         return 1;
     glfwMakeContextCurrent(window);
     glfwSwapInterval(1); // Enable vsync
+    g_AppWindow = window;
 
     // Setup Dear ImGui context
     IMGUI_CHECKVERSION();
@@ -71,82 +79,9 @@ int main(int, char**)
     //ImFont* font = io.Fonts->AddFontFromFileTTF("c:\\Windows\\Fonts\\ArialUni.ttf", 18.0f, NULL, io.Fonts->GetGlyphRangesJapanese());
     //IM_ASSERT(font != NULL);
 
-    // Our state
-    bool show_demo_window = true;
-    bool show_another_window = false;
-    ImVec4 clear_color = ImVec4(0.45f, 0.55f, 0.60f, 1.00f);
-
     // Main loop
     while (!glfwWindowShouldClose(window))
-    {
-        // Poll and handle events (inputs, window resize, etc.)
-        // You can read the io.WantCaptureMouse, io.WantCaptureKeyboard flags to tell if dear imgui wants to use your inputs.
-        // - When io.WantCaptureMouse is true, do not dispatch mouse input data to your main application, or clear/overwrite your copy of the mouse data.
-        // - When io.WantCaptureKeyboard is true, do not dispatch keyboard input data to your main application, or clear/overwrite your copy of the keyboard data.
-        // Generally you may always pass all inputs to dear imgui, and hide them from your application based on those two flags.
-        glfwPollEvents();
-
-        // Start the Dear ImGui frame
-        ImGui_ImplOpenGL2_NewFrame();
-        ImGui_ImplGlfw_NewFrame();
-        ImGui::NewFrame();
-
-        // 1. Show the big demo window (Most of the sample code is in ImGui::ShowDemoWindow()! You can browse its code to learn more about Dear ImGui!).
-        if (show_demo_window)
-            ImGui::ShowDemoWindow(&show_demo_window);
-
-        // 2. Show a simple window that we create ourselves. We use a Begin/End pair to create a named window.
-        {
-            static float f = 0.0f;
-            static int counter = 0;
-
-            ImGui::Begin("Hello, world!");                          // Create a window called "Hello, world!" and append into it.
-
-            ImGui::Text("This is some useful text.");               // Display some text (you can use a format strings too)
-            ImGui::Checkbox("Demo Window", &show_demo_window);      // Edit bools storing our window open/close state
-            ImGui::Checkbox("Another Window", &show_another_window);
-
-            ImGui::SliderFloat("float", &f, 0.0f, 1.0f);            // Edit 1 float using a slider from 0.0f to 1.0f
-            ImGui::ColorEdit3("clear color", (float*)&clear_color); // Edit 3 floats representing a color
-
-            if (ImGui::Button("Button"))                            // Buttons return true when clicked (most widgets return true when edited/activated)
-                counter++;
-            ImGui::SameLine();
-            ImGui::Text("counter = %d", counter);
-
-            ImGui::Text("Application average %.3f ms/frame (%.1f FPS)", 1000.0f / ImGui::GetIO().Framerate, ImGui::GetIO().Framerate);
-            ImGui::End();
-        }
-
-        // 3. Show another simple window.
-        if (show_another_window)
-        {
-            ImGui::Begin("Another Window", &show_another_window);   // Pass a pointer to our bool variable (the window will have a closing button that will clear the bool when clicked)
-            ImGui::Text("Hello from another window!");
-            if (ImGui::Button("Close Me"))
-                show_another_window = false;
-            ImGui::End();
-        }
-
-        // Rendering
-        ImGui::Render();
-        int display_w, display_h;
-        glfwGetFramebufferSize(window, &display_w, &display_h);
-        glViewport(0, 0, display_w, display_h);
-        glClearColor(clear_color.x * clear_color.w, clear_color.y * clear_color.w, clear_color.z * clear_color.w, clear_color.w);
-        glClear(GL_COLOR_BUFFER_BIT);
-
-        // If you are using this code with non-legacy OpenGL header/contexts (which you should not, prefer using imgui_impl_opengl3.cpp!!),
-        // you may need to backup/reset/restore other state, e.g. for current shader using the commented lines below.
-        //GLint last_program;
-        //glGetIntegerv(GL_CURRENT_PROGRAM, &last_program);
-        //glUseProgram(0);
-        ImGui_ImplOpenGL2_RenderDrawData(ImGui::GetDrawData());
-        //glUseProgram(last_program);
-
-        glfwMakeContextCurrent(window);
-        glfwSwapBuffers(window);
-    }
+        MainLoopStep();
 
     // Cleanup
     ImGui_ImplOpenGL2_Shutdown();
@@ -158,3 +93,81 @@ int main(int, char**)
 
     return 0;
 }
+
+void MainLoopStep()
+{
+    // Poll and handle events (inputs, window resize, etc.)
+    // You can read the io.WantCaptureMouse, io.WantCaptureKeyboard flags to tell if dear imgui wants to use your inputs.
+    // - When io.WantCaptureMouse is true, do not dispatch mouse input data to your main application, or clear/overwrite your copy of the mouse data.
+    // - When io.WantCaptureKeyboard is true, do not dispatch keyboard input data to your main application, or clear/overwrite your copy of the keyboard data.
+    // Generally you may always pass all inputs to dear imgui, and hide them from your application based on those two flags.
+    GLFWwindow* window = g_AppWindow;
+    glfwPollEvents();
+
+    // Start the Dear ImGui frame
+    ImGui_ImplOpenGL2_NewFrame();
+    ImGui_ImplGlfw_NewFrame();
+    ImGui::NewFrame();
+
+    // Our state
+    // (we use static, which essentially makes the variable globals, as a convenience to keep the example code easy to follow)
+    static bool show_demo_window = true;
+    static bool show_another_window = false;
+    static ImVec4 clear_color = ImVec4(0.45f, 0.55f, 0.60f, 1.00f);
+
+    // 1. Show the big demo window (Most of the sample code is in ImGui::ShowDemoWindow()! You can browse its code to learn more about Dear ImGui!).
+    if (show_demo_window)
+        ImGui::ShowDemoWindow(&show_demo_window);
+
+    // 2. Show a simple window that we create ourselves. We use a Begin/End pair to create a named window.
+    {
+        static float f = 0.0f;
+        static int counter = 0;
+
+        ImGui::Begin("Hello, world!");                          // Create a window called "Hello, world!" and append into it.
+
+        ImGui::Text("This is some useful text.");               // Display some text (you can use a format strings too)
+        ImGui::Checkbox("Demo Window", &show_demo_window);      // Edit bools storing our window open/close state
+        ImGui::Checkbox("Another Window", &show_another_window);
+
+        ImGui::SliderFloat("float", &f, 0.0f, 1.0f);            // Edit 1 float using a slider from 0.0f to 1.0f
+        ImGui::ColorEdit3("clear color", (float*)&clear_color); // Edit 3 floats representing a color
+
+        if (ImGui::Button("Button"))                            // Buttons return true when clicked (most widgets return true when edited/activated)
+            counter++;
+        ImGui::SameLine();
+        ImGui::Text("counter = %d", counter);
+
+        ImGui::Text("Application average %.3f ms/frame (%.1f FPS)", 1000.0f / ImGui::GetIO().Framerate, ImGui::GetIO().Framerate);
+        ImGui::End();
+    }
+
+    // 3. Show another simple window.
+    if (show_another_window)
+    {
+        ImGui::Begin("Another Window", &show_another_window);   // Pass a pointer to our bool variable (the window will have a closing button that will clear the bool when clicked)
+        ImGui::Text("Hello from another window!");
+        if (ImGui::Button("Close Me"))
+            show_another_window = false;
+        ImGui::End();
+    }
+
+    // Rendering
+    ImGui::Render();
+    int display_w, display_h;
+    glfwGetFramebufferSize(window, &display_w, &display_h);
+    glViewport(0, 0, display_w, display_h);
+    glClearColor(clear_color.x * clear_color.w, clear_color.y * clear_color.w, clear_color.z * clear_color.w, clear_color.w);
+    glClear(GL_COLOR_BUFFER_BIT);
+
+    // If you are using this code with non-legacy OpenGL header/contexts (which you should not, prefer using imgui_impl_opengl3.cpp!!),
+    // you may need to backup/reset/restore other state, e.g. for current shader using the commented lines below.
+    //GLint last_program;
+    //glGetIntegerv(GL_CURRENT_PROGRAM, &last_program);
+    //glUseProgram(0);
+    ImGui_ImplOpenGL2_RenderDrawData(ImGui::GetDrawData());
+    //glUseProgram(last_program);
+
+    glfwMakeContextCurrent(window);
+    glfwSwapBuffers(window);
+}

examples/example_glfw_opengl3/main.cpp

@@ -20,14 +20,19 @@
 #pragma comment(lib, "legacy_stdio_definitions")
 #endif
 
+// Data
+static GLFWwindow* g_AppWindow = NULL;
+
+// Forward declarations of helper functions
+void MainLoopStep();
 static void glfw_error_callback(int error, const char* description)
 {
-    fprintf(stderr, "Glfw Error %d: %s\n", error, description);
+    fprintf(stderr, "GLFW Error %d: %s\n", error, description);
 }
 
+// Main code
 int main(int, char**)
 {
-    // Setup window
     glfwSetErrorCallback(glfw_error_callback);
     if (!glfwInit())
         return 1;
@@ -61,6 +66,7 @@ int main(int, char**)
         return 1;
     glfwMakeContextCurrent(window);
     glfwSwapInterval(1); // Enable vsync
+    g_AppWindow = window;
 
     // Setup Dear ImGui context
     IMGUI_CHECKVERSION();
@@ -93,74 +99,9 @@ int main(int, char**)
     //ImFont* font = io.Fonts->AddFontFromFileTTF("c:\\Windows\\Fonts\\ArialUni.ttf", 18.0f, NULL, io.Fonts->GetGlyphRangesJapanese());
     //IM_ASSERT(font != NULL);
 
-    // Our state
-    bool show_demo_window = true;
-    bool show_another_window = false;
-    ImVec4 clear_color = ImVec4(0.45f, 0.55f, 0.60f, 1.00f);
-
     // Main loop
     while (!glfwWindowShouldClose(window))
-    {
-        // Poll and handle events (inputs, window resize, etc.)
-        // You can read the io.WantCaptureMouse, io.WantCaptureKeyboard flags to tell if dear imgui wants to use your inputs.
-        // - When io.WantCaptureMouse is true, do not dispatch mouse input data to your main application, or clear/overwrite your copy of the mouse data.
-        // - When io.WantCaptureKeyboard is true, do not dispatch keyboard input data to your main application, or clear/overwrite your copy of the keyboard data.
-        // Generally you may always pass all inputs to dear imgui, and hide them from your application based on those two flags.
-        glfwPollEvents();
-
-        // Start the Dear ImGui frame
-        ImGui_ImplOpenGL3_NewFrame();
-        ImGui_ImplGlfw_NewFrame();
-        ImGui::NewFrame();
-
-        // 1. Show the big demo window (Most of the sample code is in ImGui::ShowDemoWindow()! You can browse its code to learn more about Dear ImGui!).
-        if (show_demo_window)
-            ImGui::ShowDemoWindow(&show_demo_window);
-
-        // 2. Show a simple window that we create ourselves. We use a Begin/End pair to create a named window.
-        {
-            static float f = 0.0f;
-            static int counter = 0;
-
-            ImGui::Begin("Hello, world!");                          // Create a window called "Hello, world!" and append into it.
-
-            ImGui::Text("This is some useful text.");               // Display some text (you can use a format strings too)
-            ImGui::Checkbox("Demo Window", &show_demo_window);      // Edit bools storing our window open/close state
-            ImGui::Checkbox("Another Window", &show_another_window);
-
-            ImGui::SliderFloat("float", &f, 0.0f, 1.0f);            // Edit 1 float using a slider from 0.0f to 1.0f
-            ImGui::ColorEdit3("clear color", (float*)&clear_color); // Edit 3 floats representing a color
-
-            if (ImGui::Button("Button"))                            // Buttons return true when clicked (most widgets return true when edited/activated)
-                counter++;
-            ImGui::SameLine();
-            ImGui::Text("counter = %d", counter);
-
-            ImGui::Text("Application average %.3f ms/frame (%.1f FPS)", 1000.0f / ImGui::GetIO().Framerate, ImGui::GetIO().Framerate);
-            ImGui::End();
-        }
-
-        // 3. Show another simple window.
-        if (show_another_window)
-        {
-            ImGui::Begin("Another Window", &show_another_window);   // Pass a pointer to our bool variable (the window will have a closing button that will clear the bool when clicked)
-            ImGui::Text("Hello from another window!");
-            if (ImGui::Button("Close Me"))
-                show_another_window = false;
-            ImGui::End();
-        }
-
-        // Rendering
-        ImGui::Render();
-        int display_w, display_h;
-        glfwGetFramebufferSize(window, &display_w, &display_h);
-        glViewport(0, 0, display_w, display_h);
-        glClearColor(clear_color.x * clear_color.w, clear_color.y * clear_color.w, clear_color.z * clear_color.w, clear_color.w);
-        glClear(GL_COLOR_BUFFER_BIT);
-        ImGui_ImplOpenGL3_RenderDrawData(ImGui::GetDrawData());
-
-        glfwSwapBuffers(window);
-    }
+        MainLoopStep();
 
     // Cleanup
     ImGui_ImplOpenGL3_Shutdown();
@@ -172,3 +113,73 @@ int main(int, char**)
 
     return 0;
 }
+
+void MainLoopStep()
+{
+    // Poll and handle events (inputs, window resize, etc.)
+    // You can read the io.WantCaptureMouse, io.WantCaptureKeyboard flags to tell if dear imgui wants to use your inputs.
+    // - When io.WantCaptureMouse is true, do not dispatch mouse input data to your main application, or clear/overwrite your copy of the mouse data.
+    // - When io.WantCaptureKeyboard is true, do not dispatch keyboard input data to your main application, or clear/overwrite your copy of the keyboard data.
+    // Generally you may always pass all inputs to dear imgui, and hide them from your application based on those two flags.
+    GLFWwindow* window = g_AppWindow;
+    glfwPollEvents();
+
+    // Start the Dear ImGui frame
+    ImGui_ImplOpenGL3_NewFrame();
+    ImGui_ImplGlfw_NewFrame();
+    ImGui::NewFrame();
+
+    // Our state
+    // (we use static, which essentially makes the variable globals, as a convenience to keep the example code easy to follow)
+    static bool show_demo_window = true;
+    static bool show_another_window = false;
+    static ImVec4 clear_color = ImVec4(0.45f, 0.55f, 0.60f, 1.00f);
+
+    // 1. Show the big demo window (Most of the sample code is in ImGui::ShowDemoWindow()! You can browse its code to learn more about Dear ImGui!).
+    if (show_demo_window)
+        ImGui::ShowDemoWindow(&show_demo_window);
+
+    // 2. Show a simple window that we create ourselves. We use a Begin/End pair to create a named window.
+    {
+        static float f = 0.0f;
+        static int counter = 0;
+
+        ImGui::Begin("Hello, world!");                          // Create a window called "Hello, world!" and append into it.
+
+        ImGui::Text("This is some useful text.");               // Display some text (you can use a format strings too)
+        ImGui::Checkbox("Demo Window", &show_demo_window);      // Edit bools storing our window open/close state
+        ImGui::Checkbox("Another Window", &show_another_window);
+
+        ImGui::SliderFloat("float", &f, 0.0f, 1.0f);            // Edit 1 float using a slider from 0.0f to 1.0f
+        ImGui::ColorEdit3("clear color", (float*)&clear_color); // Edit 3 floats representing a color
+
+        if (ImGui::Button("Button"))                            // Buttons return true when clicked (most widgets return true when edited/activated)
+            counter++;
+        ImGui::SameLine();
+        ImGui::Text("counter = %d", counter);
+
+        ImGui::Text("Application average %.3f ms/frame (%.1f FPS)", 1000.0f / ImGui::GetIO().Framerate, ImGui::GetIO().Framerate);
+        ImGui::End();
+    }
+
+    // 3. Show another simple window.
+    if (show_another_window)
+    {
+        ImGui::Begin("Another Window", &show_another_window);   // Pass a pointer to our bool variable (the window will have a closing button that will clear the bool when clicked)
+        ImGui::Text("Hello from another window!");
+        if (ImGui::Button("Close Me"))
+            show_another_window = false;
+        ImGui::End();
+    }
+
+    // Rendering
+    ImGui::Render();
+    int display_w, display_h;
+    glfwGetFramebufferSize(window, &display_w, &display_h);
+    glViewport(0, 0, display_w, display_h);
+    glClearColor(clear_color.x * clear_color.w, clear_color.y * clear_color.w, clear_color.z * clear_color.w, clear_color.w);
+    glClear(GL_COLOR_BUFFER_BIT);
+    ImGui_ImplOpenGL3_RenderDrawData(ImGui::GetDrawData());
+
+    glfwSwapBuffers(window);
+}

examples/example_glfw_vulkan/main.cpp

@@ -31,6 +31,7 @@
 #define IMGUI_VULKAN_DEBUG_REPORT
 #endif
 
+// Data
 static VkAllocationCallbacks*   g_Allocator = NULL;
 static VkInstance               g_Instance = VK_NULL_HANDLE;
 static VkPhysicalDevice         g_PhysicalDevice = VK_NULL_HANDLE;
@@ -41,10 +42,17 @@ static VkDebugReportCallbackEXT g_DebugReport = VK_NULL_HANDLE;
 static VkPipelineCache          g_PipelineCache = VK_NULL_HANDLE;
 static VkDescriptorPool         g_DescriptorPool = VK_NULL_HANDLE;
 
+static GLFWwindow*              g_AppWindow = NULL;
 static ImGui_ImplVulkanH_Window g_MainWindowData;
 static int                      g_MinImageCount = 2;
 static bool                     g_SwapChainRebuild = false;
 
+// Forward declarations of helper functions
+void MainLoopStep();
+static void glfw_error_callback(int error, const char* description)
+{
+    fprintf(stderr, "GLFW Error %d: %s\n", error, description);
+}
 static void check_vk_result(VkResult err)
 {
     if (err == 0)
@@ -347,22 +355,16 @@ static void FramePresent(ImGui_ImplVulkanH_Window* wd)
     wd->SemaphoreIndex = (wd->SemaphoreIndex + 1) % wd->ImageCount; // Now we can use the next set of semaphores
 }
 
-static void glfw_error_callback(int error, const char* description)
-{
-    fprintf(stderr, "Glfw Error %d: %s\n", error, description);
-}
-
+// Main code
 int main(int, char**)
 {
-    // Setup GLFW window
     glfwSetErrorCallback(glfw_error_callback);
     if (!glfwInit())
         return 1;
 
+    // Create window with Vulkan context
     glfwWindowHint(GLFW_CLIENT_API, GLFW_NO_API);
     GLFWwindow* window = glfwCreateWindow(1280, 720, "Dear ImGui GLFW+Vulkan example", NULL, NULL);
-
-    // Setup Vulkan
     if (!glfwVulkanSupported())
     {
         printf("GLFW: Vulkan Not Supported\n");
@@ -371,6 +373,7 @@ int main(int, char**)
     uint32_t extensions_count = 0;
     const char** extensions = glfwGetRequiredInstanceExtensions(&extensions_count);
     SetupVulkan(extensions, extensions_count);
+    g_AppWindow = window;
 
     // Create Window Surface
     VkSurfaceKHR surface;
@@ -458,91 +461,9 @@ int main(int, char**)
         ImGui_ImplVulkan_DestroyFontUploadObjects();
     }
 
-    // Our state
-    bool show_demo_window = true;
-    bool show_another_window = false;
-    ImVec4 clear_color = ImVec4(0.45f, 0.55f, 0.60f, 1.00f);
-
     // Main loop
     while (!glfwWindowShouldClose(window))
-    {
-        // Poll and handle events (inputs, window resize, etc.)
-        // You can read the io.WantCaptureMouse, io.WantCaptureKeyboard flags to tell if dear imgui wants to use your inputs.
-        // - When io.WantCaptureMouse is true, do not dispatch mouse input data to your main application, or clear/overwrite your copy of the mouse data.
-        // - When io.WantCaptureKeyboard is true, do not dispatch keyboard input data to your main application, or clear/overwrite your copy of the keyboard data.
-        // Generally you may always pass all inputs to dear imgui, and hide them from your application based on those two flags.
-        glfwPollEvents();
-
-        // Resize swap chain?
-        if (g_SwapChainRebuild)
-        {
-            int width, height;
-            glfwGetFramebufferSize(window, &width, &height);
-            if (width > 0 && height > 0)
-            {
-                ImGui_ImplVulkan_SetMinImageCount(g_MinImageCount);
-                ImGui_ImplVulkanH_CreateOrResizeWindow(g_Instance, g_PhysicalDevice, g_Device, &g_MainWindowData, g_QueueFamily, g_Allocator, width, height, g_MinImageCount);
-                g_MainWindowData.FrameIndex = 0;
-                g_SwapChainRebuild = false;
-            }
-        }
-
-        // Start the Dear ImGui frame
-        ImGui_ImplVulkan_NewFrame();
-        ImGui_ImplGlfw_NewFrame();
-        ImGui::NewFrame();
-
-        // 1. Show the big demo window (Most of the sample code is in ImGui::ShowDemoWindow()! You can browse its code to learn more about Dear ImGui!).
-        if (show_demo_window)
-            ImGui::ShowDemoWindow(&show_demo_window);
-
-        // 2. Show a simple window that we create ourselves. We use a Begin/End pair to create a named window.
-        {
-            static float f = 0.0f;
-            static int counter = 0;
-
-            ImGui::Begin("Hello, world!");                          // Create a window called "Hello, world!" and append into it.
-
-            ImGui::Text("This is some useful text.");               // Display some text (you can use a format strings too)
-            ImGui::Checkbox("Demo Window", &show_demo_window);      // Edit bools storing our window open/close state
-            ImGui::Checkbox("Another Window", &show_another_window);
-
-            ImGui::SliderFloat("float", &f, 0.0f, 1.0f);            // Edit 1 float using a slider from 0.0f to 1.0f
-            ImGui::ColorEdit3("clear color", (float*)&clear_color); // Edit 3 floats representing a color
-
-            if (ImGui::Button("Button"))                            // Buttons return true when clicked (most widgets return true when edited/activated)
-                counter++;
-            ImGui::SameLine();
-            ImGui::Text("counter = %d", counter);
-
-            ImGui::Text("Application average %.3f ms/frame (%.1f FPS)", 1000.0f / ImGui::GetIO().Framerate, ImGui::GetIO().Framerate);
-            ImGui::End();
-        }
-
-        // 3. Show another simple window.
-        if (show_another_window)
-        {
-            ImGui::Begin("Another Window", &show_another_window);   // Pass a pointer to our bool variable (the window will have a closing button that will clear the bool when clicked)
-            ImGui::Text("Hello from another window!");
-            if (ImGui::Button("Close Me"))
-                show_another_window = false;
-            ImGui::End();
-        }
-
-        // Rendering
-        ImGui::Render();
-        ImDrawData* draw_data = ImGui::GetDrawData();
-        const bool is_minimized = (draw_data->DisplaySize.x <= 0.0f || draw_data->DisplaySize.y <= 0.0f);
-        if (!is_minimized)
-        {
-            wd->ClearValue.color.float32[0] = clear_color.x * clear_color.w;
-            wd->ClearValue.color.float32[1] = clear_color.y * clear_color.w;
-            wd->ClearValue.color.float32[2] = clear_color.z * clear_color.w;
-            wd->ClearValue.color.float32[3] = clear_color.w;
-            FrameRender(wd, draw_data);
-            FramePresent(wd);
-        }
-    }
+        MainLoopStep();
 
     // Cleanup
     err = vkDeviceWaitIdle(g_Device);
@@ -559,3 +480,91 @@ int main(int, char**)
 
     return 0;
 }
+
+void MainLoopStep()
+{
+    // Poll and handle events (inputs, window resize, etc.)
+    // You can read the io.WantCaptureMouse, io.WantCaptureKeyboard flags to tell if dear imgui wants to use your inputs.
+    // - When io.WantCaptureMouse is true, do not dispatch mouse input data to your main application, or clear/overwrite your copy of the mouse data.
+    // - When io.WantCaptureKeyboard is true, do not dispatch keyboard input data to your main application, or clear/overwrite your copy of the keyboard data.
+    // Generally you may always pass all inputs to dear imgui, and hide them from your application based on those two flags.
+    GLFWwindow* window = g_AppWindow;
+    glfwPollEvents();
+
+    // Resize swap chain?
+    if (g_SwapChainRebuild)
+    {
+        int width, height;
+        glfwGetFramebufferSize(window, &width, &height);
+        if (width > 0 && height > 0)
+        {
+            ImGui_ImplVulkan_SetMinImageCount(g_MinImageCount);
+            ImGui_ImplVulkanH_CreateOrResizeWindow(g_Instance, g_PhysicalDevice, g_Device, &g_MainWindowData, g_QueueFamily, g_Allocator, width, height, g_MinImageCount);
+            g_MainWindowData.FrameIndex = 0;
+            g_SwapChainRebuild = false;
+        }
+    }
+
+    // Start the Dear ImGui frame
+    ImGui_ImplVulkan_NewFrame();
+    ImGui_ImplGlfw_NewFrame();
+    ImGui::NewFrame();
+
+    // Our state
+    // (we use static, which essentially makes the variable globals, as a convenience to keep the example code easy to follow)
+    static bool show_demo_window = true;
+    static bool show_another_window = false;
+    static ImVec4 clear_color = ImVec4(0.45f, 0.55f, 0.60f, 1.00f);
+
+    // 1. Show the big demo window (Most of the sample code is in ImGui::ShowDemoWindow()! You can browse its code to learn more about Dear ImGui!).
+    if (show_demo_window)
+        ImGui::ShowDemoWindow(&show_demo_window);
+
+    // 2. Show a simple window that we create ourselves. We use a Begin/End pair to create a named window.
+    {
+        static float f = 0.0f;
+        static int counter = 0;
+
+        ImGui::Begin("Hello, world!");                          // Create a window called "Hello, world!" and append into it.
+
+        ImGui::Text("This is some useful text.");               // Display some text (you can use a format strings too)
+        ImGui::Checkbox("Demo Window", &show_demo_window);      // Edit bools storing our window open/close state
+        ImGui::Checkbox("Another Window", &show_another_window);
+
+        ImGui::SliderFloat("float", &f, 0.0f, 1.0f);            // Edit 1 float using a slider from 0.0f to 1.0f
+        ImGui::ColorEdit3("clear color", (float*)&clear_color); // Edit 3 floats representing a color
+
+        if (ImGui::Button("Button"))                            // Buttons return true when clicked (most widgets return true when edited/activated)
+            counter++;
+        ImGui::SameLine();
+        ImGui::Text("counter = %d", counter);
+
+        ImGui::Text("Application average %.3f ms/frame (%.1f FPS)", 1000.0f / ImGui::GetIO().Framerate, ImGui::GetIO().Framerate);
+        ImGui::End();
+    }
+
+    // 3. Show another simple window.
+    if (show_another_window)
+    {
+        ImGui::Begin("Another Window", &show_another_window);   // Pass a pointer to our bool variable (the window will have a closing button that will clear the bool when clicked)
+        ImGui::Text("Hello from another window!");
+        if (ImGui::Button("Close Me"))
+            show_another_window = false;
+        ImGui::End();
+    }
+
+    // Rendering
+    ImGui::Render();
+    ImDrawData* draw_data = ImGui::GetDrawData();
+    const bool is_minimized = (draw_data->DisplaySize.x <= 0.0f || draw_data->DisplaySize.y <= 0.0f);
+    if (!is_minimized)
+    {
+        ImGui_ImplVulkanH_Window* wd = &g_MainWindowData;
+        wd->ClearValue.color.float32[0] = clear_color.x * clear_color.w;
+        wd->ClearValue.color.float32[1] = clear_color.y * clear_color.w;
+        wd->ClearValue.color.float32[2] = clear_color.z * clear_color.w;
+        wd->ClearValue.color.float32[3] = clear_color.w;
+        FrameRender(wd, draw_data);
+        FramePresent(wd);
+    }
+}

examples/example_glut_opengl2/main.cpp

@@ -19,86 +19,23 @@
 #include "imgui_impl_opengl2.h"
 #define GL_SILENCE_DEPRECATION
 #ifdef __APPLE__
-    #include <GLUT/glut.h>
+#include <GLUT/glut.h>
 #else
-    #include <GL/freeglut.h>
+#include <GL/freeglut.h>
 #endif
 
 #ifdef _MSC_VER
 #pragma warning (disable: 4505) // unreferenced local function has been removed
 #endif
 
+// Forward declarations of helper functions
+void MainLoopStep();
+
 // Our state
 static bool show_demo_window = true;
 static bool show_another_window = false;
 static ImVec4 clear_color = ImVec4(0.45f, 0.55f, 0.60f, 1.00f);
 
-void my_display_code()
-{
-    // 1. Show the big demo window (Most of the sample code is in ImGui::ShowDemoWindow()! You can browse its code to learn more about Dear ImGui!).
-    if (show_demo_window)
-        ImGui::ShowDemoWindow(&show_demo_window);
-
-    // 2. Show a simple window that we create ourselves. We use a Begin/End pair to create a named window.
-    {
-        static float f = 0.0f;
-        static int counter = 0;
-
-        ImGui::Begin("Hello, world!");                          // Create a window called "Hello, world!" and append into it.
-
-        ImGui::Text("This is some useful text.");               // Display some text (you can use a format strings too)
-        ImGui::Checkbox("Demo Window", &show_demo_window);      // Edit bools storing our window open/close state
-        ImGui::Checkbox("Another Window", &show_another_window);
-
-        ImGui::SliderFloat("float", &f, 0.0f, 1.0f);            // Edit 1 float using a slider from 0.0f to 1.0f
-        ImGui::ColorEdit3("clear color", (float*)&clear_color); // Edit 3 floats representing a color
-
-        if (ImGui::Button("Button"))                            // Buttons return true when clicked (most widgets return true when edited/activated)
-            counter++;
-        ImGui::SameLine();
-        ImGui::Text("counter = %d", counter);
-
-        ImGui::Text("Application average %.3f ms/frame (%.1f FPS)", 1000.0f / ImGui::GetIO().Framerate, ImGui::GetIO().Framerate);
-        ImGui::End();
-    }
-
-    // 3. Show another simple window.
-    if (show_another_window)
-    {
-        ImGui::Begin("Another Window", &show_another_window);   // Pass a pointer to our bool variable (the window will have a closing button that will clear the bool when clicked)
-        ImGui::Text("Hello from another window!");
-        if (ImGui::Button("Close Me"))
-            show_another_window = false;
-        ImGui::End();
-    }
-}
-
-void glut_display_func()
-{
-    // Start the Dear ImGui frame
-    ImGui_ImplOpenGL2_NewFrame();
-    ImGui_ImplGLUT_NewFrame();
-
-    my_display_code();
-
-    // Rendering
-    ImGui::Render();
-    ImGuiIO& io = ImGui::GetIO();
-    glViewport(0, 0, (GLsizei)io.DisplaySize.x, (GLsizei)io.DisplaySize.y);
-    glClearColor(clear_color.x * clear_color.w, clear_color.y * clear_color.w, clear_color.z * clear_color.w, clear_color.w);
-    glClear(GL_COLOR_BUFFER_BIT);
-    //glUseProgram(0); // You may want this if using this code in an OpenGL 3+ context where shaders may be bound, but prefer using the GL3+ code.
-    ImGui_ImplOpenGL2_RenderDrawData(ImGui::GetDrawData());
-
-    glutSwapBuffers();
-    glutPostRedisplay();
-}
-
-// You can read the io.WantCaptureMouse, io.WantCaptureKeyboard flags to tell if dear imgui wants to use your inputs.
-// - When io.WantCaptureMouse is true, do not dispatch mouse input data to your main application, or clear/overwrite your copy of the mouse data.
-// - When io.WantCaptureKeyboard is true, do not dispatch keyboard input data to your main application, or clear/overwrite your copy of the keyboard data.
-// Generally you may always pass all inputs to dear imgui, and hide them from your application based on those two flags.
-
 int main(int argc, char** argv)
 {
     // Create GLUT window
@@ -113,7 +50,7 @@ int main(int argc, char** argv)
     // Setup GLUT display function
     // We will also call ImGui_ImplGLUT_InstallFuncs() to get all the other functions installed for us,
     // otherwise it is possible to install our own functions and call the imgui_impl_glut.h functions ourselves.
-    glutDisplayFunc(glut_display_func);
+    glutDisplayFunc(MainLoopStep);
 
     // Setup Dear ImGui context
     IMGUI_CHECKVERSION();
@@ -128,9 +65,16 @@ int main(int argc, char** argv)
     // Setup Platform/Renderer backends
     // FIXME: Consider reworking this example to install our own GLUT funcs + forward calls ImGui_ImplGLUT_XXX ones, instead of using ImGui_ImplGLUT_InstallFuncs().
     ImGui_ImplGLUT_Init();
-    ImGui_ImplGLUT_InstallFuncs();
     ImGui_ImplOpenGL2_Init();
 
+    // Install GLUT handlers (glutReshapeFunc(), glutMotionFunc(), glutPassiveMotionFunc(), glutMouseFunc(), glutKeyboardFunc() etc.)
+    // You can read the io.WantCaptureMouse, io.WantCaptureKeyboard flags to tell if dear imgui wants to use your inputs.
+    // - When io.WantCaptureMouse is true, do not dispatch mouse input data to your main application, or clear/overwrite your copy of the mouse data.
+    // - When io.WantCaptureKeyboard is true, do not dispatch keyboard input data to your main application, or clear/overwrite your copy of the keyboard data.
+    // Generally you may always pass all inputs to dear imgui, and hide them from your application based on those two flags.
+    ImGui_ImplGLUT_InstallFuncs();
+
+
     // Load Fonts
     // - If no fonts are loaded, dear imgui will use the default font. You can also load multiple fonts and use ImGui::PushFont()/PopFont() to select them.
     // - AddFontFromFileTTF() will return the ImFont* so you can store it if you need to select the font among multiple.
@@ -147,6 +91,7 @@ int main(int argc, char** argv)
     //ImFont* font = io.Fonts->AddFontFromFileTTF("c:\\Windows\\Fonts\\ArialUni.ttf", 18.0f, NULL, io.Fonts->GetGlyphRangesJapanese());
     //IM_ASSERT(font != NULL);
 
+    // Main loop
     glutMainLoop();
 
     // Cleanup
@@ -156,3 +101,59 @@ int main(int argc, char** argv)
 
     return 0;
 }
+
+void MainLoopStep()
+{
+    // Start the Dear ImGui frame
+    ImGui_ImplOpenGL2_NewFrame();
+    ImGui_ImplGLUT_NewFrame();
+
+    // 1. Show the big demo window (Most of the sample code is in ImGui::ShowDemoWindow()! You can browse its code to learn more about Dear ImGui!).
+    if (show_demo_window)
+        ImGui::ShowDemoWindow(&show_demo_window);
+
+    // 2. Show a simple window that we create ourselves. We use a Begin/End pair to create a named window.
+    {
+        static float f = 0.0f;
+        static int counter = 0;
+
+        ImGui::Begin("Hello, world!");                          // Create a window called "Hello, world!" and append into it.
+
+        ImGui::Text("This is some useful text.");               // Display some text (you can use a format strings too)
+        ImGui::Checkbox("Demo Window", &show_demo_window);      // Edit bools storing our window open/close state
+        ImGui::Checkbox("Another Window", &show_another_window);
+
+        ImGui::SliderFloat("float", &f, 0.0f, 1.0f);            // Edit 1 float using a slider from 0.0f to 1.0f
+        ImGui::ColorEdit3("clear color", (float*)&clear_color); // Edit 3 floats representing a color
+
+        if (ImGui::Button("Button"))                            // Buttons return true when clicked (most widgets return true when edited/activated)
+            counter++;
+        ImGui::SameLine();
+        ImGui::Text("counter = %d", counter);
+
+        ImGui::Text("Application average %.3f ms/frame (%.1f FPS)", 1000.0f / ImGui::GetIO().Framerate, ImGui::GetIO().Framerate);
+        ImGui::End();
+    }
+
+    // 3. Show another simple window.
+    if (show_another_window)
+    {
+        ImGui::Begin("Another Window", &show_another_window);   // Pass a pointer to our bool variable (the window will have a closing button that will clear the bool when clicked)
+        ImGui::Text("Hello from another window!");
+        if (ImGui::Button("Close Me"))
+            show_another_window = false;
+        ImGui::End();
+    }
+
+    // Rendering
+    ImGui::Render();
+    ImGuiIO& io = ImGui::GetIO();
+    glViewport(0, 0, (GLsizei)io.DisplaySize.x, (GLsizei)io.DisplaySize.y);
+    glClearColor(clear_color.x * clear_color.w, clear_color.y * clear_color.w, clear_color.z * clear_color.w, clear_color.w);
+    glClear(GL_COLOR_BUFFER_BIT);
+    //glUseProgram(0); // You may want this if using this code in an OpenGL 3+ context where shaders may be bound, but prefer using the GL3+ code.
+    ImGui_ImplOpenGL2_RenderDrawData(ImGui::GetDrawData());
+
+    glutSwapBuffers();
+    glutPostRedisplay();
+}

examples/example_sdl_directx11/main.cpp

@@ -12,12 +12,14 @@
 #include <SDL_syswm.h>
 
 // Data
+static SDL_Window*              g_AppWindow = NULL;
 static ID3D11Device*            g_pd3dDevice = NULL;
 static ID3D11DeviceContext*     g_pd3dDeviceContext = NULL;
 static IDXGISwapChain*          g_pSwapChain = NULL;
 static ID3D11RenderTargetView*  g_mainRenderTargetView = NULL;
 
 // Forward declarations of helper functions
+bool MainLoopStep();
 bool CreateDeviceD3D(HWND hWnd);
 void CleanupDeviceD3D();
 void CreateRenderTarget();
@@ -42,6 +44,7 @@ int main(int, char**)
     SDL_VERSION(&wmInfo.version);
     SDL_GetWindowWMInfo(window, &wmInfo);
     HWND hwnd = (HWND)wmInfo.info.win.window;
+    g_AppWindow = window;
 
     // Initialize Direct3D
     if (!CreateDeviceD3D(hwnd))
@@ -81,104 +84,111 @@ int main(int, char**)
     //ImFont* font = io.Fonts->AddFontFromFileTTF("c:\\Windows\\Fonts\\ArialUni.ttf", 18.0f, NULL, io.Fonts->GetGlyphRangesJapanese());
     //IM_ASSERT(font != NULL);
 
-    // Our state
-    bool show_demo_window = true;
-    bool show_another_window = false;
-    ImVec4 clear_color = ImVec4(0.45f, 0.55f, 0.60f, 1.00f);
-
     // Main loop
-    bool done = false;
-    while (!done)
+    while (true)
     {
-        // Poll and handle events (inputs, window resize, etc.)
-        // You can read the io.WantCaptureMouse, io.WantCaptureKeyboard flags to tell if dear imgui wants to use your inputs.
-        // - When io.WantCaptureMouse is true, do not dispatch mouse input data to your main application, or clear/overwrite your copy of the mouse data.
-        // - When io.WantCaptureKeyboard is true, do not dispatch keyboard input data to your main application, or clear/overwrite your copy of the keyboard data.
-        // Generally you may always pass all inputs to dear imgui, and hide them from your application based on those two flags.
-        SDL_Event event;
-        while (SDL_PollEvent(&event))
-        {
-            ImGui_ImplSDL2_ProcessEvent(&event);
-            if (event.type == SDL_QUIT)
-                done = true;
-            if (event.type == SDL_WINDOWEVENT && event.window.event == SDL_WINDOWEVENT_CLOSE && event.window.windowID == SDL_GetWindowID(window))
-                done = true;
-            if (event.type == SDL_WINDOWEVENT && event.window.event == SDL_WINDOWEVENT_RESIZED && event.window.windowID == SDL_GetWindowID(window))
-            {
-                // Release all outstanding references to the swap chain's buffers before resizing.
-                CleanupRenderTarget();
-                g_pSwapChain->ResizeBuffers(0, 0, 0, DXGI_FORMAT_UNKNOWN, 0);
-                CreateRenderTarget();
-            }
-        }
+        if (!MainLoopStep())
+            break;
+    }
 
-        // Start the Dear ImGui frame
-        ImGui_ImplDX11_NewFrame();
-        ImGui_ImplSDL2_NewFrame();
-        ImGui::NewFrame();
+    // Cleanup
+    ImGui_ImplDX11_Shutdown();
+    ImGui_ImplSDL2_Shutdown();
+    ImGui::DestroyContext();
 
-        // 1. Show the big demo window (Most of the sample code is in ImGui::ShowDemoWindow()! You can browse its code to learn more about Dear ImGui!).
-        if (show_demo_window)
-            ImGui::ShowDemoWindow(&show_demo_window);
+    CleanupDeviceD3D();
+    SDL_DestroyWindow(window);
+    SDL_Quit();
+
+    return 0;
+}
 
-        // 2. Show a simple window that we create ourselves. We use a Begin/End pair to create a named window.
+bool MainLoopStep()
+{
+    // Poll and handle SDL events (inputs, window resize, etc.)
+    // You can read the io.WantCaptureMouse, io.WantCaptureKeyboard flags to tell if dear imgui wants to use your inputs.
+    // - When io.WantCaptureMouse is true, do not dispatch mouse input data to your main application, or clear/overwrite your copy of the mouse data.
+    // - When io.WantCaptureKeyboard is true, do not dispatch keyboard input data to your main application, or clear/overwrite your copy of the keyboard data.
+    // Generally you may always pass all inputs to dear imgui, and hide them from your application based on those two flags.
+    SDL_Window* window = g_AppWindow;
+    SDL_Event event;
+    while (SDL_PollEvent(&event))
+    {
+        ImGui_ImplSDL2_ProcessEvent(&event);
+        if (event.type == SDL_QUIT)
+            return false;
+        if (event.type == SDL_WINDOWEVENT && event.window.event == SDL_WINDOWEVENT_CLOSE && event.window.windowID == SDL_GetWindowID(window))
+            return false;
+        if (event.type == SDL_WINDOWEVENT && event.window.event == SDL_WINDOWEVENT_RESIZED && event.window.windowID == SDL_GetWindowID(window))
         {
-            static float f = 0.0f;
-            static int counter = 0;
+            // Release all outstanding references to the swap chain's buffers before resizing.
+            CleanupRenderTarget();
+            g_pSwapChain->ResizeBuffers(0, 0, 0, DXGI_FORMAT_UNKNOWN, 0);
+            CreateRenderTarget();
+        }
+    }
 
-            ImGui::Begin("Hello, world!");                          // Create a window called "Hello, world!" and append into it.
+    // Start the Dear ImGui frame
+    ImGui_ImplDX11_NewFrame();
+    ImGui_ImplSDL2_NewFrame();
+    ImGui::NewFrame();
 
-            ImGui::Text("This is some useful text.");               // Display some text (you can use a format strings too)
-            ImGui::Checkbox("Demo Window", &show_demo_window);      // Edit bools storing our window open/close state
-            ImGui::Checkbox("Another Window", &show_another_window);
+    // Our state
+    // (we use static, which essentially makes the variable globals, as a convenience to keep the example code easy to follow)
+    static bool show_demo_window = true;
+    static bool show_another_window = false;
+    static ImVec4 clear_color = ImVec4(0.45f, 0.55f, 0.60f, 1.00f);
 
-            ImGui::SliderFloat("float", &f, 0.0f, 1.0f);            // Edit 1 float using a slider from 0.0f to 1.0f
-            ImGui::ColorEdit3("clear color", (float*)&clear_color); // Edit 3 floats representing a color
+    // 1. Show the big demo window (Most of the sample code is in ImGui::ShowDemoWindow()! You can browse its code to learn more about Dear ImGui!).
+    if (show_demo_window)
+        ImGui::ShowDemoWindow(&show_demo_window);
 
-            if (ImGui::Button("Button"))                            // Buttons return true when clicked (most widgets return true when edited/activated)
-                counter++;
-            ImGui::SameLine();
-            ImGui::Text("counter = %d", counter);
+    // 2. Show a simple window that we create ourselves. We use a Begin/End pair to create a named window.
+    {
+        static float f = 0.0f;
+        static int counter = 0;
 
-            ImGui::Text("Application average %.3f ms/frame (%.1f FPS)", 1000.0f / ImGui::GetIO().Framerate, ImGui::GetIO().Framerate);
-            ImGui::End();
-        }
+        ImGui::Begin("Hello, world!");                          // Create a window called "Hello, world!" and append into it.
 
-        // 3. Show another simple window.
-        if (show_another_window)
-        {
-            ImGui::Begin("Another Window", &show_another_window);   // Pass a pointer to our bool variable (the window will have a closing button that will clear the bool when clicked)
-            ImGui::Text("Hello from another window!");
-            if (ImGui::Button("Close Me"))
-                show_another_window = false;
-            ImGui::End();
-        }
+        ImGui::Text("This is some useful text.");               // Display some text (you can use a format strings too)
+        ImGui::Checkbox("Demo Window", &show_demo_window);      // Edit bools storing our window open/close state
+        ImGui::Checkbox("Another Window", &show_another_window);
 
-        // Rendering
-        ImGui::Render();
-        const float clear_color_with_alpha[4] = { clear_color.x * clear_color.w, clear_color.y * clear_color.w, clear_color.z * clear_color.w, clear_color.w };
-        g_pd3dDeviceContext->OMSetRenderTargets(1, &g_mainRenderTargetView, NULL);
-        g_pd3dDeviceContext->ClearRenderTargetView(g_mainRenderTargetView, clear_color_with_alpha);
-        ImGui_ImplDX11_RenderDrawData(ImGui::GetDrawData());
+        ImGui::SliderFloat("float", &f, 0.0f, 1.0f);            // Edit 1 float using a slider from 0.0f to 1.0f
+        ImGui::ColorEdit3("clear color", (float*)&clear_color); // Edit 3 floats representing a color
 
-        g_pSwapChain->Present(1, 0); // Present with vsync
-        //g_pSwapChain->Present(0, 0); // Present without vsync
+        if (ImGui::Button("Button"))                            // Buttons return true when clicked (most widgets return true when edited/activated)
+            counter++;
+        ImGui::SameLine();
+        ImGui::Text("counter = %d", counter);
+
+        ImGui::Text("Application average %.3f ms/frame (%.1f FPS)", 1000.0f / ImGui::GetIO().Framerate, ImGui::GetIO().Framerate);
+        ImGui::End();
     }
 
-    // Cleanup
-    ImGui_ImplDX11_Shutdown();
-    ImGui_ImplSDL2_Shutdown();
-    ImGui::DestroyContext();
+    // 3. Show another simple window.
+    if (show_another_window)
+    {
+        ImGui::Begin("Another Window", &show_another_window);   // Pass a pointer to our bool variable (the window will have a closing button that will clear the bool when clicked)
+        ImGui::Text("Hello from another window!");
+        if (ImGui::Button("Close Me"))
+            show_another_window = false;
+        ImGui::End();
+    }
 
-    CleanupDeviceD3D();
-    SDL_DestroyWindow(window);
-    SDL_Quit();
+    // Rendering
+    ImGui::Render();
+    const float clear_color_with_alpha[4] = { clear_color.x * clear_color.w, clear_color.y * clear_color.w, clear_color.z * clear_color.w, clear_color.w };
+    g_pd3dDeviceContext->OMSetRenderTargets(1, &g_mainRenderTargetView, NULL);
+    g_pd3dDeviceContext->ClearRenderTargetView(g_mainRenderTargetView, clear_color_with_alpha);
+    ImGui_ImplDX11_RenderDrawData(ImGui::GetDrawData());
+    g_pSwapChain->Present(1, 0); // Present with vsync
+    //g_pSwapChain->Present(0, 0); // Present without vsync
 
-    return 0;
+    return true;
 }
 
-// Helper functions
-
+// Helper functions to use DirectX11
 bool CreateDeviceD3D(HWND hWnd)
 {
     // Setup swap chain

examples/example_sdl_opengl2/main.cpp

@@ -14,12 +14,16 @@
 #include <SDL.h>
 #include <SDL_opengl.h>
 
+// Data
+static SDL_Window* g_AppWindow = NULL;
+
+// Forward declarations of helper functions
+bool MainLoopStep();
+
 // Main code
 int main(int, char**)
 {
     // Setup SDL
-    // (Some versions of SDL before <2.0.10 appears to have performance/stalling issues on a minority of Windows systems,
-    // depending on whether SDL_INIT_GAMECONTROLLER is enabled or disabled.. updating to the latest version of SDL is recommended!)
     if (SDL_Init(SDL_INIT_VIDEO | SDL_INIT_TIMER | SDL_INIT_GAMECONTROLLER) != 0)
     {
         printf("Error: %s\n", SDL_GetError());
@@ -37,6 +41,7 @@ int main(int, char**)
     SDL_GLContext gl_context = SDL_GL_CreateContext(window);
     SDL_GL_MakeCurrent(window, gl_context);
     SDL_GL_SetSwapInterval(1); // Enable vsync
+    g_AppWindow = window;
 
     // Setup Dear ImGui context
     IMGUI_CHECKVERSION();
@@ -69,80 +74,11 @@ int main(int, char**)
     //ImFont* font = io.Fonts->AddFontFromFileTTF("c:\\Windows\\Fonts\\ArialUni.ttf", 18.0f, NULL, io.Fonts->GetGlyphRangesJapanese());
     //IM_ASSERT(font != NULL);
 
-    // Our state
-    bool show_demo_window = true;
-    bool show_another_window = false;
-    ImVec4 clear_color = ImVec4(0.45f, 0.55f, 0.60f, 1.00f);
-
     // Main loop
-    bool done = false;
-    while (!done)
+    while (true)
     {
-        // Poll and handle events (inputs, window resize, etc.)
-        // You can read the io.WantCaptureMouse, io.WantCaptureKeyboard flags to tell if dear imgui wants to use your inputs.
-        // - When io.WantCaptureMouse is true, do not dispatch mouse input data to your main application, or clear/overwrite your copy of the mouse data.
-        // - When io.WantCaptureKeyboard is true, do not dispatch keyboard input data to your main application, or clear/overwrite your copy of the keyboard data.
-        // Generally you may always pass all inputs to dear imgui, and hide them from your application based on those two flags.
-        SDL_Event event;
-        while (SDL_PollEvent(&event))
-        {
-            ImGui_ImplSDL2_ProcessEvent(&event);
-            if (event.type == SDL_QUIT)
-                done = true;
-            if (event.type == SDL_WINDOWEVENT && event.window.event == SDL_WINDOWEVENT_CLOSE && event.window.windowID == SDL_GetWindowID(window))
-                done = true;
-        }
-
-        // Start the Dear ImGui frame
-        ImGui_ImplOpenGL2_NewFrame();
-        ImGui_ImplSDL2_NewFrame();
-        ImGui::NewFrame();
-
-        // 1. Show the big demo window (Most of the sample code is in ImGui::ShowDemoWindow()! You can browse its code to learn more about Dear ImGui!).
-        if (show_demo_window)
-            ImGui::ShowDemoWindow(&show_demo_window);
-
-        // 2. Show a simple window that we create ourselves. We use a Begin/End pair to create a named window.
-        {
-            static float f = 0.0f;
-            static int counter = 0;
-
-            ImGui::Begin("Hello, world!");                          // Create a window called "Hello, world!" and append into it.
-
-            ImGui::Text("This is some useful text.");               // Display some text (you can use a format strings too)
-            ImGui::Checkbox("Demo Window", &show_demo_window);      // Edit bools storing our window open/close state
-            ImGui::Checkbox("Another Window", &show_another_window);
-
-            ImGui::SliderFloat("float", &f, 0.0f, 1.0f);            // Edit 1 float using a slider from 0.0f to 1.0f
-            ImGui::ColorEdit3("clear color", (float*)&clear_color); // Edit 3 floats representing a color
-
-            if (ImGui::Button("Button"))                            // Buttons return true when clicked (most widgets return true when edited/activated)
-                counter++;
-            ImGui::SameLine();
-            ImGui::Text("counter = %d", counter);
-
-            ImGui::Text("Application average %.3f ms/frame (%.1f FPS)", 1000.0f / ImGui::GetIO().Framerate, ImGui::GetIO().Framerate);
-            ImGui::End();
-        }
-
-        // 3. Show another simple window.
-        if (show_another_window)
-        {
-            ImGui::Begin("Another Window", &show_another_window);   // Pass a pointer to our bool variable (the window will have a closing button that will clear the bool when clicked)
-            ImGui::Text("Hello from another window!");
-            if (ImGui::Button("Close Me"))
-                show_another_window = false;
-            ImGui::End();
-        }
-
-        // Rendering
-        ImGui::Render();
-        glViewport(0, 0, (int)io.DisplaySize.x, (int)io.DisplaySize.y);
-        glClearColor(clear_color.x * clear_color.w, clear_color.y * clear_color.w, clear_color.z * clear_color.w, clear_color.w);
-        glClear(GL_COLOR_BUFFER_BIT);
-        //glUseProgram(0); // You may want this if using this code in an OpenGL 3+ context where shaders may be bound
-        ImGui_ImplOpenGL2_RenderDrawData(ImGui::GetDrawData());
-        SDL_GL_SwapWindow(window);
+        if (!MainLoopStep())
+            break;
     }
 
     // Cleanup
@@ -156,3 +92,82 @@ int main(int, char**)
 
     return 0;
 }
+
+bool MainLoopStep()
+{
+    // Poll and handle SDL events (inputs, window resize, etc.)
+    // You can read the io.WantCaptureMouse, io.WantCaptureKeyboard flags to tell if dear imgui wants to use your inputs.
+    // - When io.WantCaptureMouse is true, do not dispatch mouse input data to your main application, or clear/overwrite your copy of the mouse data.
+    // - When io.WantCaptureKeyboard is true, do not dispatch keyboard input data to your main application, or clear/overwrite your copy of the keyboard data.
+    // Generally you may always pass all inputs to dear imgui, and hide them from your application based on those two flags.
+    SDL_Window* window = g_AppWindow;
+    SDL_Event event;
+    while (SDL_PollEvent(&event))
+    {
+        ImGui_ImplSDL2_ProcessEvent(&event);
+        if (event.type == SDL_QUIT)
+            return false;
+        if (event.type == SDL_WINDOWEVENT && event.window.event == SDL_WINDOWEVENT_CLOSE && event.window.windowID == SDL_GetWindowID(window))
+            return false;
+    }
+
+    // Start the Dear ImGui frame
+    ImGuiIO& io = ImGui::GetIO();
+    ImGui_ImplOpenGL2_NewFrame();
+    ImGui_ImplSDL2_NewFrame();
+    ImGui::NewFrame();
+
+    // Our state
+    // (we use static, which essentially makes the variable globals, as a convenience to keep the example code easy to follow)
+    static bool show_demo_window = true;
+    static bool show_another_window = false;
+    static ImVec4 clear_color = ImVec4(0.45f, 0.55f, 0.60f, 1.00f);
+
+    // 1. Show the big demo window (Most of the sample code is in ImGui::ShowDemoWindow()! You can browse its code to learn more about Dear ImGui!).
+    if (show_demo_window)
+        ImGui::ShowDemoWindow(&show_demo_window);
+
+    // 2. Show a simple window that we create ourselves. We use a Begin/End pair to create a named window.
+    {
+        static float f = 0.0f;
+        static int counter = 0;
+
+        ImGui::Begin("Hello, world!");                          // Create a window called "Hello, world!" and append into it.
+
+        ImGui::Text("This is some useful text.");               // Display some text (you can use a format strings too)
+        ImGui::Checkbox("Demo Window", &show_demo_window);      // Edit bools storing our window open/close state
+        ImGui::Checkbox("Another Window", &show_another_window);
+
+        ImGui::SliderFloat("float", &f, 0.0f, 1.0f);            // Edit 1 float using a slider from 0.0f to 1.0f
+        ImGui::ColorEdit3("clear color", (float*)&clear_color); // Edit 3 floats representing a color
+
+        if (ImGui::Button("Button"))                            // Buttons return true when clicked (most widgets return true when edited/activated)
+            counter++;
+        ImGui::SameLine();
+        ImGui::Text("counter = %d", counter);
+
+        ImGui::Text("Application average %.3f ms/frame (%.1f FPS)", 1000.0f / ImGui::GetIO().Framerate, ImGui::GetIO().Framerate);
+        ImGui::End();
+    }
+
+    // 3. Show another simple window.
+    if (show_another_window)
+    {
+        ImGui::Begin("Another Window", &show_another_window);   // Pass a pointer to our bool variable (the window will have a closing button that will clear the bool when clicked)
+        ImGui::Text("Hello from another window!");
+        if (ImGui::Button("Close Me"))
+            show_another_window = false;
+        ImGui::End();
+    }
+
+    // Rendering
+    ImGui::Render();
+    glViewport(0, 0, (int)io.DisplaySize.x, (int)io.DisplaySize.y);
+    glClearColor(clear_color.x * clear_color.w, clear_color.y * clear_color.w, clear_color.z * clear_color.w, clear_color.w);
+    glClear(GL_COLOR_BUFFER_BIT);
+    //glUseProgram(0); // You may want this if using this code in an OpenGL 3+ context where shaders may be bound
+    ImGui_ImplOpenGL2_RenderDrawData(ImGui::GetDrawData());
+    SDL_GL_SwapWindow(window);
+
+    return true;
+}

examples/example_sdl_opengl3/main.cpp

@@ -14,12 +14,16 @@
 #include <SDL_opengl.h>
 #endif
 
+// Data
+static SDL_Window* g_AppWindow = NULL;
+
+// Forward declarations of helper functions
+bool MainLoopStep();
+
 // Main code
 int main(int, char**)
 {
     // Setup SDL
-    // (Some versions of SDL before <2.0.10 appears to have performance/stalling issues on a minority of Windows systems,
-    // depending on whether SDL_INIT_GAMECONTROLLER is enabled or disabled.. updating to the latest version of SDL is recommended!)
     if (SDL_Init(SDL_INIT_VIDEO | SDL_INIT_TIMER | SDL_INIT_GAMECONTROLLER) != 0)
     {
         printf("Error: %s\n", SDL_GetError());
@@ -59,6 +63,7 @@ int main(int, char**)
     SDL_GLContext gl_context = SDL_GL_CreateContext(window);
     SDL_GL_MakeCurrent(window, gl_context);
     SDL_GL_SetSwapInterval(1); // Enable vsync
+    g_AppWindow = window;
 
     // Setup Dear ImGui context
     IMGUI_CHECKVERSION();
@@ -91,79 +96,11 @@ int main(int, char**)
     //ImFont* font = io.Fonts->AddFontFromFileTTF("c:\\Windows\\Fonts\\ArialUni.ttf", 18.0f, NULL, io.Fonts->GetGlyphRangesJapanese());
     //IM_ASSERT(font != NULL);
 
-    // Our state
-    bool show_demo_window = true;
-    bool show_another_window = false;
-    ImVec4 clear_color = ImVec4(0.45f, 0.55f, 0.60f, 1.00f);
-
     // Main loop
-    bool done = false;
-    while (!done)
+    while (true)
     {
-        // Poll and handle events (inputs, window resize, etc.)
-        // You can read the io.WantCaptureMouse, io.WantCaptureKeyboard flags to tell if dear imgui wants to use your inputs.
-        // - When io.WantCaptureMouse is true, do not dispatch mouse input data to your main application, or clear/overwrite your copy of the mouse data.
-        // - When io.WantCaptureKeyboard is true, do not dispatch keyboard input data to your main application, or clear/overwrite your copy of the keyboard data.
-        // Generally you may always pass all inputs to dear imgui, and hide them from your application based on those two flags.
-        SDL_Event event;
-        while (SDL_PollEvent(&event))
-        {
-            ImGui_ImplSDL2_ProcessEvent(&event);
-            if (event.type == SDL_QUIT)
-                done = true;
-            if (event.type == SDL_WINDOWEVENT && event.window.event == SDL_WINDOWEVENT_CLOSE && event.window.windowID == SDL_GetWindowID(window))
-                done = true;
-        }
-
-        // Start the Dear ImGui frame
-        ImGui_ImplOpenGL3_NewFrame();
-        ImGui_ImplSDL2_NewFrame();
-        ImGui::NewFrame();
-
-        // 1. Show the big demo window (Most of the sample code is in ImGui::ShowDemoWindow()! You can browse its code to learn more about Dear ImGui!).
-        if (show_demo_window)
-            ImGui::ShowDemoWindow(&show_demo_window);
-
-        // 2. Show a simple window that we create ourselves. We use a Begin/End pair to create a named window.
-        {
-            static float f = 0.0f;
-            static int counter = 0;
-
-            ImGui::Begin("Hello, world!");                          // Create a window called "Hello, world!" and append into it.
-
-            ImGui::Text("This is some useful text.");               // Display some text (you can use a format strings too)
-            ImGui::Checkbox("Demo Window", &show_demo_window);      // Edit bools storing our window open/close state
-            ImGui::Checkbox("Another Window", &show_another_window);
-
-            ImGui::SliderFloat("float", &f, 0.0f, 1.0f);            // Edit 1 float using a slider from 0.0f to 1.0f
-            ImGui::ColorEdit3("clear color", (float*)&clear_color); // Edit 3 floats representing a color
-
-            if (ImGui::Button("Button"))                            // Buttons return true when clicked (most widgets return true when edited/activated)
-                counter++;
-            ImGui::SameLine();
-            ImGui::Text("counter = %d", counter);
-
-            ImGui::Text("Application average %.3f ms/frame (%.1f FPS)", 1000.0f / ImGui::GetIO().Framerate, ImGui::GetIO().Framerate);
-            ImGui::End();
-        }
-
-        // 3. Show another simple window.
-        if (show_another_window)
-        {
-            ImGui::Begin("Another Window", &show_another_window);   // Pass a pointer to our bool variable (the window will have a closing button that will clear the bool when clicked)
-            ImGui::Text("Hello from another window!");
-            if (ImGui::Button("Close Me"))
-                show_another_window = false;
-            ImGui::End();
-        }
-
-        // Rendering
-        ImGui::Render();
-        glViewport(0, 0, (int)io.DisplaySize.x, (int)io.DisplaySize.y);
-        glClearColor(clear_color.x * clear_color.w, clear_color.y * clear_color.w, clear_color.z * clear_color.w, clear_color.w);
-        glClear(GL_COLOR_BUFFER_BIT);
-        ImGui_ImplOpenGL3_RenderDrawData(ImGui::GetDrawData());
-        SDL_GL_SwapWindow(window);
+        if (!MainLoopStep())
+            break;
     }
 
     // Cleanup
@@ -177,3 +114,81 @@ int main(int, char**)
 
     return 0;
 }
+
+bool MainLoopStep()
+{
+    // Poll and handle SDL events (inputs, window resize, etc.)
+    // You can read the io.WantCaptureMouse, io.WantCaptureKeyboard flags to tell if dear imgui wants to use your inputs.
+    // - When io.WantCaptureMouse is true, do not dispatch mouse input data to your main application, or clear/overwrite your copy of the mouse data.
+    // - When io.WantCaptureKeyboard is true, do not dispatch keyboard input data to your main application, or clear/overwrite your copy of the keyboard data.
+    // Generally you may always pass all inputs to dear imgui, and hide them from your application based on those two flags.
+    SDL_Window* window = g_AppWindow;
+    SDL_Event event;
+    while (SDL_PollEvent(&event))
+    {
+        ImGui_ImplSDL2_ProcessEvent(&event);
+        if (event.type == SDL_QUIT)
+            return false;
+        if (event.type == SDL_WINDOWEVENT && event.window.event == SDL_WINDOWEVENT_CLOSE && event.window.windowID == SDL_GetWindowID(window))
+            return false;
+    }
+
+    // Start the Dear ImGui frame
+    ImGuiIO& io = ImGui::GetIO();
+    ImGui_ImplOpenGL3_NewFrame();
+    ImGui_ImplSDL2_NewFrame();
+    ImGui::NewFrame();
+
+    // Our state
+    // (we use static, which essentially makes the variable globals, as a convenience to keep the example code easy to follow)
+    static bool show_demo_window = true;
+    static bool show_another_window = false;
+    static ImVec4 clear_color = ImVec4(0.45f, 0.55f, 0.60f, 1.00f);
+
+    // 1. Show the big demo window (Most of the sample code is in ImGui::ShowDemoWindow()! You can browse its code to learn more about Dear ImGui!).
+    if (show_demo_window)
+        ImGui::ShowDemoWindow(&show_demo_window);
+
+    // 2. Show a simple window that we create ourselves. We use a Begin/End pair to create a named window.
+    {
+        static float f = 0.0f;
+        static int counter = 0;
+
+        ImGui::Begin("Hello, world!");                          // Create a window called "Hello, world!" and append into it.
+
+        ImGui::Text("This is some useful text.");               // Display some text (you can use a format strings too)
+        ImGui::Checkbox("Demo Window", &show_demo_window);      // Edit bools storing our window open/close state
+        ImGui::Checkbox("Another Window", &show_another_window);
+
+        ImGui::SliderFloat("float", &f, 0.0f, 1.0f);            // Edit 1 float using a slider from 0.0f to 1.0f
+        ImGui::ColorEdit3("clear color", (float*)&clear_color); // Edit 3 floats representing a color
+
+        if (ImGui::Button("Button"))                            // Buttons return true when clicked (most widgets return true when edited/activated)
+            counter++;
+        ImGui::SameLine();
+        ImGui::Text("counter = %d", counter);
+
+        ImGui::Text("Application average %.3f ms/frame (%.1f FPS)", 1000.0f / ImGui::GetIO().Framerate, ImGui::GetIO().Framerate);
+        ImGui::End();
+    }
+
+    // 3. Show another simple window.
+    if (show_another_window)
+    {
+        ImGui::Begin("Another Window", &show_another_window);   // Pass a pointer to our bool variable (the window will have a closing button that will clear the bool when clicked)
+        ImGui::Text("Hello from another window!");
+        if (ImGui::Button("Close Me"))
+            show_another_window = false;
+        ImGui::End();
+    }
+
+    // Rendering
+    ImGui::Render();
+    glViewport(0, 0, (int)io.DisplaySize.x, (int)io.DisplaySize.y);
+    glClearColor(clear_color.x * clear_color.w, clear_color.y * clear_color.w, clear_color.z * clear_color.w, clear_color.w);
+    glClear(GL_COLOR_BUFFER_BIT);
+    ImGui_ImplOpenGL3_RenderDrawData(ImGui::GetDrawData());
+    SDL_GL_SwapWindow(window);
+
+    return true;
+}

examples/example_sdl_sdlrenderer/main.cpp

@@ -17,29 +17,34 @@
 #error This backend requires SDL 2.0.17+ because of SDL_RenderGeometry() function
 #endif
 
+// Data
+static SDL_Window*      g_AppWindow = NULL;
+static SDL_Renderer*    g_AppWindowRenderer = NULL;
+
+// Forward declarations of helper functions
+bool MainLoopStep();
+
 // Main code
 int main(int, char**)
 {
     // Setup SDL
-    // (Some versions of SDL before <2.0.10 appears to have performance/stalling issues on a minority of Windows systems,
-    // depending on whether SDL_INIT_GAMECONTROLLER is enabled or disabled.. updating to the latest version of SDL is recommended!)
     if (SDL_Init(SDL_INIT_VIDEO | SDL_INIT_TIMER | SDL_INIT_GAMECONTROLLER) != 0)
     {
         printf("Error: %s\n", SDL_GetError());
         return -1;
     }
 
-    // Setup window
+    // Create window with SDL_Renderer graphics context
     SDL_WindowFlags window_flags = (SDL_WindowFlags)(SDL_WINDOW_RESIZABLE | SDL_WINDOW_ALLOW_HIGHDPI);
     SDL_Window* window = SDL_CreateWindow("Dear ImGui SDL2+SDL_Renderer example", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, 1280, 720, window_flags);
-
-    // Setup SDL_Renderer instance
     SDL_Renderer* renderer = SDL_CreateRenderer(window, -1, SDL_RENDERER_PRESENTVSYNC | SDL_RENDERER_ACCELERATED);
     if (renderer == NULL)
     {
         SDL_Log("Error creating SDL_Renderer!");
         return 0;
     }
+    g_AppWindow = window;
+    g_AppWindowRenderer = renderer;
     //SDL_RendererInfo info;
     //SDL_GetRendererInfo(renderer, &info);
     //SDL_Log("Current SDL_Renderer: %s", info.name);
@@ -75,79 +80,11 @@ int main(int, char**)
     //ImFont* font = io.Fonts->AddFontFromFileTTF("c:\\Windows\\Fonts\\ArialUni.ttf", 18.0f, NULL, io.Fonts->GetGlyphRangesJapanese());
     //IM_ASSERT(font != NULL);
 
-    // Our state
-    bool show_demo_window = true;
-    bool show_another_window = false;
-    ImVec4 clear_color = ImVec4(0.45f, 0.55f, 0.60f, 1.00f);
-
     // Main loop
-    bool done = false;
-    while (!done)
+    while (true)
     {
-        // Poll and handle events (inputs, window resize, etc.)
-        // You can read the io.WantCaptureMouse, io.WantCaptureKeyboard flags to tell if dear imgui wants to use your inputs.
-        // - When io.WantCaptureMouse is true, do not dispatch mouse input data to your main application, or clear/overwrite your copy of the mouse data.
-        // - When io.WantCaptureKeyboard is true, do not dispatch keyboard input data to your main application, or clear/overwrite your copy of the keyboard data.
-        // Generally you may always pass all inputs to dear imgui, and hide them from your application based on those two flags.
-        SDL_Event event;
-        while (SDL_PollEvent(&event))
-        {
-            ImGui_ImplSDL2_ProcessEvent(&event);
-            if (event.type == SDL_QUIT)
-                done = true;
-            if (event.type == SDL_WINDOWEVENT && event.window.event == SDL_WINDOWEVENT_CLOSE && event.window.windowID == SDL_GetWindowID(window))
-                done = true;
-        }
-
-        // Start the Dear ImGui frame
-        ImGui_ImplSDLRenderer_NewFrame();
-        ImGui_ImplSDL2_NewFrame();
-        ImGui::NewFrame();
-
-        // 1. Show the big demo window (Most of the sample code is in ImGui::ShowDemoWindow()! You can browse its code to learn more about Dear ImGui!).
-        if (show_demo_window)
-            ImGui::ShowDemoWindow(&show_demo_window);
-
-        // 2. Show a simple window that we create ourselves. We use a Begin/End pair to create a named window.
-        {
-            static float f = 0.0f;
-            static int counter = 0;
-
-            ImGui::Begin("Hello, world!");                          // Create a window called "Hello, world!" and append into it.
-
-            ImGui::Text("This is some useful text.");               // Display some text (you can use a format strings too)
-            ImGui::Checkbox("Demo Window", &show_demo_window);      // Edit bools storing our window open/close state
-            ImGui::Checkbox("Another Window", &show_another_window);
-
-            ImGui::SliderFloat("float", &f, 0.0f, 1.0f);            // Edit 1 float using a slider from 0.0f to 1.0f
-            ImGui::ColorEdit3("clear color", (float*)&clear_color); // Edit 3 floats representing a color
-
-            if (ImGui::Button("Button"))                            // Buttons return true when clicked (most widgets return true when edited/activated)
-                counter++;
-            ImGui::SameLine();
-            ImGui::Text("counter = %d", counter);
-
-            ImGui::Text("Application average %.3f ms/frame (%.1f FPS)", 1000.0f / ImGui::GetIO().Framerate, ImGui::GetIO().Framerate);
-            ImGui::End();
-        }
-
-        // 3. Show another simple window.
-        if (show_another_window)
-        {
-            ImGui::Begin("Another Window", &show_another_window);   // Pass a pointer to our bool variable (the window will have a closing button that will clear the bool when clicked)
-            ImGui::Text("Hello from another window!");
-            if (ImGui::Button("Close Me"))
-                show_another_window = false;
-            ImGui::End();
-        }
-
-        // Rendering
-        ImGui::Render();
-        SDL_RenderSetScale(renderer, io.DisplayFramebufferScale.x, io.DisplayFramebufferScale.y);
-        SDL_SetRenderDrawColor(renderer, (Uint8)(clear_color.x * 255), (Uint8)(clear_color.y * 255), (Uint8)(clear_color.z * 255), (Uint8)(clear_color.w * 255));
-        SDL_RenderClear(renderer);
-        ImGui_ImplSDLRenderer_RenderDrawData(ImGui::GetDrawData());
-        SDL_RenderPresent(renderer);
+        if (!MainLoopStep())
+            break;
     }
 
     // Cleanup
@@ -161,3 +98,82 @@ int main(int, char**)
 
     return 0;
 }
+
+bool MainLoopStep()
+{
+    // Poll and handle events (inputs, window resize, etc.)
+    // You can read the io.WantCaptureMouse, io.WantCaptureKeyboard flags to tell if dear imgui wants to use your inputs.
+    // - When io.WantCaptureMouse is true, do not dispatch mouse input data to your main application, or clear/overwrite your copy of the mouse data.
+    // - When io.WantCaptureKeyboard is true, do not dispatch keyboard input data to your main application, or clear/overwrite your copy of the keyboard data.
+    // Generally you may always pass all inputs to dear imgui, and hide them from your application based on those two flags.
+    SDL_Window* window = g_AppWindow;
+    SDL_Renderer* renderer = g_AppWindowRenderer;
+    SDL_Event event;
+    while (SDL_PollEvent(&event))
+    {
+        ImGui_ImplSDL2_ProcessEvent(&event);
+        if (event.type == SDL_QUIT)
+            return false;
+        if (event.type == SDL_WINDOWEVENT && event.window.event == SDL_WINDOWEVENT_CLOSE && event.window.windowID == SDL_GetWindowID(window))
+            return false;
+    }
+
+    // Start the Dear ImGui frame
+    ImGuiIO& io = ImGui::GetIO();
+    ImGui_ImplSDLRenderer_NewFrame();
+    ImGui_ImplSDL2_NewFrame();
+    ImGui::NewFrame();
+
+    // Our state
+    // (we use static, which essentially makes the variable globals, as a convenience to keep the example code easy to follow)
+    static bool show_demo_window = true;
+    static bool show_another_window = false;
+    static ImVec4 clear_color = ImVec4(0.45f, 0.55f, 0.60f, 1.00f);
+
+    // 1. Show the big demo window (Most of the sample code is in ImGui::ShowDemoWindow()! You can browse its code to learn more about Dear ImGui!).
+    if (show_demo_window)
+        ImGui::ShowDemoWindow(&show_demo_window);
+
+    // 2. Show a simple window that we create ourselves. We use a Begin/End pair to create a named window.
+    {
+        static float f = 0.0f;
+        static int counter = 0;
+
+        ImGui::Begin("Hello, world!");                          // Create a window called "Hello, world!" and append into it.
+
+        ImGui::Text("This is some useful text.");               // Display some text (you can use a format strings too)
+        ImGui::Checkbox("Demo Window", &show_demo_window);      // Edit bools storing our window open/close state
+        ImGui::Checkbox("Another Window", &show_another_window);
+
+        ImGui::SliderFloat("float", &f, 0.0f, 1.0f);            // Edit 1 float using a slider from 0.0f to 1.0f
+        ImGui::ColorEdit3("clear color", (float*)&clear_color); // Edit 3 floats representing a color
+
+        if (ImGui::Button("Button"))                            // Buttons return true when clicked (most widgets return true when edited/activated)
+            counter++;
+        ImGui::SameLine();
+        ImGui::Text("counter = %d", counter);
+
+        ImGui::Text("Application average %.3f ms/frame (%.1f FPS)", 1000.0f / ImGui::GetIO().Framerate, ImGui::GetIO().Framerate);
+        ImGui::End();
+    }
+
+    // 3. Show another simple window.
+    if (show_another_window)
+    {
+        ImGui::Begin("Another Window", &show_another_window);   // Pass a pointer to our bool variable (the window will have a closing button that will clear the bool when clicked)
+        ImGui::Text("Hello from another window!");
+        if (ImGui::Button("Close Me"))
+            show_another_window = false;
+        ImGui::End();
+    }
+
+    // Rendering
+    ImGui::Render();
+    SDL_RenderSetScale(renderer, io.DisplayFramebufferScale.x, io.DisplayFramebufferScale.y);
+    SDL_SetRenderDrawColor(renderer, (Uint8)(clear_color.x * 255), (Uint8)(clear_color.y * 255), (Uint8)(clear_color.z * 255), (Uint8)(clear_color.w * 255));
+    SDL_RenderClear(renderer);
+    ImGui_ImplSDLRenderer_RenderDrawData(ImGui::GetDrawData());
+    SDL_RenderPresent(renderer);
+
+    return true;
+}

examples/example_sdl_vulkan/example_sdl_vulkan.vcxproj.filters

@@ -32,7 +32,7 @@
       <Filter>imgui</Filter>
     </ClCompile>
     <ClCompile Include="..\..\imgui_tables.cpp">
-      <Filter>sources</Filter>
+      <Filter>imgui</Filter>
     </ClCompile>
   </ItemGroup>
   <ItemGroup>

examples/example_sdl_vulkan/main.cpp

@@ -23,6 +23,7 @@
 #define IMGUI_VULKAN_DEBUG_REPORT
 #endif
 
+// Data
 static VkAllocationCallbacks*   g_Allocator = NULL;
 static VkInstance               g_Instance = VK_NULL_HANDLE;
 static VkPhysicalDevice         g_PhysicalDevice = VK_NULL_HANDLE;
@@ -33,10 +34,14 @@ static VkDebugReportCallbackEXT g_DebugReport = VK_NULL_HANDLE;
 static VkPipelineCache          g_PipelineCache = VK_NULL_HANDLE;
 static VkDescriptorPool         g_DescriptorPool = VK_NULL_HANDLE;
 
+static SDL_Window*              g_AppWindow = NULL;
 static ImGui_ImplVulkanH_Window g_MainWindowData;
 static uint32_t                 g_MinImageCount = 2;
 static bool                     g_SwapChainRebuild = false;
 
+// Forward declarations of helper functions
+bool MainLoopStep();
+
 static void check_vk_result(VkResult err)
 {
     if (err == 0)
@@ -339,6 +344,7 @@ static void FramePresent(ImGui_ImplVulkanH_Window* wd)
     wd->SemaphoreIndex = (wd->SemaphoreIndex + 1) % wd->ImageCount; // Now we can use the next set of semaphores
 }
 
+// Main code
 int main(int, char**)
 {
     // Setup SDL
@@ -348,17 +354,16 @@ int main(int, char**)
         return -1;
     }
 
-    // Setup window
+    // Create window with Vulkan graphics context
     SDL_WindowFlags window_flags = (SDL_WindowFlags)(SDL_WINDOW_VULKAN | SDL_WINDOW_RESIZABLE | SDL_WINDOW_ALLOW_HIGHDPI);
     SDL_Window* window = SDL_CreateWindow("Dear ImGui SDL2+Vulkan example", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, 1280, 720, window_flags);
-
-    // Setup Vulkan
     uint32_t extensions_count = 0;
     SDL_Vulkan_GetInstanceExtensions(window, &extensions_count, NULL);
     const char** extensions = new const char*[extensions_count];
     SDL_Vulkan_GetInstanceExtensions(window, &extensions_count, extensions);
     SetupVulkan(extensions, extensions_count);
     delete[] extensions;
+    g_AppWindow = window;
 
     // Create Window Surface
     VkSurfaceKHR surface;
@@ -450,99 +455,11 @@ int main(int, char**)
         ImGui_ImplVulkan_DestroyFontUploadObjects();
     }
 
-    // Our state
-    bool show_demo_window = true;
-    bool show_another_window = false;
-    ImVec4 clear_color = ImVec4(0.45f, 0.55f, 0.60f, 1.00f);
-
     // Main loop
-    bool done = false;
-    while (!done)
+    while (true)
     {
-        // Poll and handle events (inputs, window resize, etc.)
-        // You can read the io.WantCaptureMouse, io.WantCaptureKeyboard flags to tell if dear imgui wants to use your inputs.
-        // - When io.WantCaptureMouse is true, do not dispatch mouse input data to your main application, or clear/overwrite your copy of the mouse data.
-        // - When io.WantCaptureKeyboard is true, do not dispatch keyboard input data to your main application, or clear/overwrite your copy of the keyboard data.
-        // Generally you may always pass all inputs to dear imgui, and hide them from your application based on those two flags.
-        SDL_Event event;
-        while (SDL_PollEvent(&event))
-        {
-            ImGui_ImplSDL2_ProcessEvent(&event);
-            if (event.type == SDL_QUIT)
-                done = true;
-            if (event.type == SDL_WINDOWEVENT && event.window.event == SDL_WINDOWEVENT_CLOSE && event.window.windowID == SDL_GetWindowID(window))
-                done = true;
-        }
-
-        // Resize swap chain?
-        if (g_SwapChainRebuild)
-        {
-            int width, height;
-            SDL_GetWindowSize(window, &width, &height);
-            if (width > 0 && height > 0)
-            {
-                ImGui_ImplVulkan_SetMinImageCount(g_MinImageCount);
-                ImGui_ImplVulkanH_CreateOrResizeWindow(g_Instance, g_PhysicalDevice, g_Device, &g_MainWindowData, g_QueueFamily, g_Allocator, width, height, g_MinImageCount);
-                g_MainWindowData.FrameIndex = 0;
-                g_SwapChainRebuild = false;
-            }
-        }
-
-        // Start the Dear ImGui frame
-        ImGui_ImplVulkan_NewFrame();
-        ImGui_ImplSDL2_NewFrame();
-        ImGui::NewFrame();
-
-        // 1. Show the big demo window (Most of the sample code is in ImGui::ShowDemoWindow()! You can browse its code to learn more about Dear ImGui!).
-        if (show_demo_window)
-            ImGui::ShowDemoWindow(&show_demo_window);
-
-        // 2. Show a simple window that we create ourselves. We use a Begin/End pair to create a named window.
-        {
-            static float f = 0.0f;
-            static int counter = 0;
-
-            ImGui::Begin("Hello, world!");                          // Create a window called "Hello, world!" and append into it.
-
-            ImGui::Text("This is some useful text.");               // Display some text (you can use a format strings too)
-            ImGui::Checkbox("Demo Window", &show_demo_window);      // Edit bools storing our window open/close state
-            ImGui::Checkbox("Another Window", &show_another_window);
-
-            ImGui::SliderFloat("float", &f, 0.0f, 1.0f);            // Edit 1 float using a slider from 0.0f to 1.0f
-            ImGui::ColorEdit3("clear color", (float*)&clear_color); // Edit 3 floats representing a color
-
-            if (ImGui::Button("Button"))                            // Buttons return true when clicked (most widgets return true when edited/activated)
-                counter++;
-            ImGui::SameLine();
-            ImGui::Text("counter = %d", counter);
-
-            ImGui::Text("Application average %.3f ms/frame (%.1f FPS)", 1000.0f / ImGui::GetIO().Framerate, ImGui::GetIO().Framerate);
-            ImGui::End();
-        }
-
-        // 3. Show another simple window.
-        if (show_another_window)
-        {
-            ImGui::Begin("Another Window", &show_another_window);   // Pass a pointer to our bool variable (the window will have a closing button that will clear the bool when clicked)
-            ImGui::Text("Hello from another window!");
-            if (ImGui::Button("Close Me"))
-                show_another_window = false;
-            ImGui::End();
-        }
-
-        // Rendering
-        ImGui::Render();
-        ImDrawData* draw_data = ImGui::GetDrawData();
-        const bool is_minimized = (draw_data->DisplaySize.x <= 0.0f || draw_data->DisplaySize.y <= 0.0f);
-        if (!is_minimized)
-        {
-            wd->ClearValue.color.float32[0] = clear_color.x * clear_color.w;
-            wd->ClearValue.color.float32[1] = clear_color.y * clear_color.w;
-            wd->ClearValue.color.float32[2] = clear_color.z * clear_color.w;
-            wd->ClearValue.color.float32[3] = clear_color.w;
-            FrameRender(wd, draw_data);
-            FramePresent(wd);
-        }
+        if (!MainLoopStep())
+            break;
     }
 
     // Cleanup
@@ -560,3 +477,101 @@ int main(int, char**)
 
     return 0;
 }
+
+bool MainLoopStep()
+{
+    // Poll and handle events (inputs, window resize, etc.)
+    // You can read the io.WantCaptureMouse, io.WantCaptureKeyboard flags to tell if dear imgui wants to use your inputs.
+    // - When io.WantCaptureMouse is true, do not dispatch mouse input data to your main application, or clear/overwrite your copy of the mouse data.
+    // - When io.WantCaptureKeyboard is true, do not dispatch keyboard input data to your main application, or clear/overwrite your copy of the keyboard data.
+    // Generally you may always pass all inputs to dear imgui, and hide them from your application based on those two flags.
+    SDL_Window* window = g_AppWindow;
+    SDL_Event event;
+    while (SDL_PollEvent(&event))
+    {
+        ImGui_ImplSDL2_ProcessEvent(&event);
+        if (event.type == SDL_QUIT)
+            return false;
+        if (event.type == SDL_WINDOWEVENT && event.window.event == SDL_WINDOWEVENT_CLOSE && event.window.windowID == SDL_GetWindowID(window))
+            return false;
+    }
+
+    // Resize swap chain?
+    if (g_SwapChainRebuild)
+    {
+        int width, height;
+        SDL_GetWindowSize(window, &width, &height);
+        if (width > 0 && height > 0)
+        {
+            ImGui_ImplVulkan_SetMinImageCount(g_MinImageCount);
+            ImGui_ImplVulkanH_CreateOrResizeWindow(g_Instance, g_PhysicalDevice, g_Device, &g_MainWindowData, g_QueueFamily, g_Allocator, width, height, g_MinImageCount);
+            g_MainWindowData.FrameIndex = 0;
+            g_SwapChainRebuild = false;
+        }
+    }
+
+    // Start the Dear ImGui frame
+    ImGui_ImplVulkan_NewFrame();
+    ImGui_ImplSDL2_NewFrame();
+    ImGui::NewFrame();
+
+    // Our state
+    // (we use static, which essentially makes the variable globals, as a convenience to keep the example code easy to follow)
+    static bool show_demo_window = true;
+    static bool show_another_window = false;
+    static ImVec4 clear_color = ImVec4(0.45f, 0.55f, 0.60f, 1.00f);
+
+    // 1. Show the big demo window (Most of the sample code is in ImGui::ShowDemoWindow()! You can browse its code to learn more about Dear ImGui!).
+    if (show_demo_window)
+        ImGui::ShowDemoWindow(&show_demo_window);
+
+    // 2. Show a simple window that we create ourselves. We use a Begin/End pair to create a named window.
+    {
+        static float f = 0.0f;
+        static int counter = 0;
+
+        ImGui::Begin("Hello, world!");                          // Create a window called "Hello, world!" and append into it.
+
+        ImGui::Text("This is some useful text.");               // Display some text (you can use a format strings too)
+        ImGui::Checkbox("Demo Window", &show_demo_window);      // Edit bools storing our window open/close state
+        ImGui::Checkbox("Another Window", &show_another_window);
+
+        ImGui::SliderFloat("float", &f, 0.0f, 1.0f);            // Edit 1 float using a slider from 0.0f to 1.0f
+        ImGui::ColorEdit3("clear color", (float*)&clear_color); // Edit 3 floats representing a color
+
+        if (ImGui::Button("Button"))                            // Buttons return true when clicked (most widgets return true when edited/activated)
+            counter++;
+        ImGui::SameLine();
+        ImGui::Text("counter = %d", counter);
+
+        ImGui::Text("Application average %.3f ms/frame (%.1f FPS)", 1000.0f / ImGui::GetIO().Framerate, ImGui::GetIO().Framerate);
+        ImGui::End();
+    }
+
+    // 3. Show another simple window.
+    if (show_another_window)
+    {
+        ImGui::Begin("Another Window", &show_another_window);   // Pass a pointer to our bool variable (the window will have a closing button that will clear the bool when clicked)
+        ImGui::Text("Hello from another window!");
+        if (ImGui::Button("Close Me"))
+            show_another_window = false;
+        ImGui::End();
+    }
+
+    // Rendering
+    ImGui::Render();
+    ImDrawData* draw_data = ImGui::GetDrawData();
+    const bool is_minimized = (draw_data->DisplaySize.x <= 0.0f || draw_data->DisplaySize.y <= 0.0f);
+    if (!is_minimized)
+    {
+        ImGui_ImplVulkanH_Window* wd = &g_MainWindowData;
+        wd->ClearValue.color.float32[0] = clear_color.x * clear_color.w;
+        wd->ClearValue.color.float32[1] = clear_color.y * clear_color.w;
+        wd->ClearValue.color.float32[2] = clear_color.z * clear_color.w;
+        wd->ClearValue.color.float32[3] = clear_color.w;
+        FrameRender(wd, draw_data);
+        FramePresent(wd);
+    }
+
+    return true;
+}

examples/example_win32_directx10/main.cpp

@@ -15,6 +15,7 @@ static IDXGISwapChain*          g_pSwapChain = NULL;
 static ID3D10RenderTargetView*  g_mainRenderTargetView = NULL;
 
 // Forward declarations of helper functions
+bool MainLoopStep();
 bool CreateDeviceD3D(HWND hWnd);
 void CleanupDeviceD3D();
 void CreateRenderTarget();
@@ -73,90 +74,100 @@ int main(int, char**)
     //ImFont* font = io.Fonts->AddFontFromFileTTF("c:\\Windows\\Fonts\\ArialUni.ttf", 18.0f, NULL, io.Fonts->GetGlyphRangesJapanese());
     //IM_ASSERT(font != NULL);
 
-    // Our state
-    bool show_demo_window = true;
-    bool show_another_window = false;
-    ImVec4 clear_color = ImVec4(0.45f, 0.55f, 0.60f, 1.00f);
-
     // Main loop
-    bool done = false;
-    while (!done)
+    while (true)
     {
-        // Poll and handle messages (inputs, window resize, etc.)
-        // See the WndProc() function below for our to dispatch events to the Win32 backend.
-        MSG msg;
-        while (::PeekMessage(&msg, NULL, 0U, 0U, PM_REMOVE))
-        {
-            ::TranslateMessage(&msg);
-            ::DispatchMessage(&msg);
-            if (msg.message == WM_QUIT)
-                done = true;
-        }
-        if (done)
+        if (!MainLoopStep())
             break;
+    }
 
-        // Start the Dear ImGui frame
-        ImGui_ImplDX10_NewFrame();
-        ImGui_ImplWin32_NewFrame();
-        ImGui::NewFrame();
+    // Cleanup
+    ImGui_ImplDX10_Shutdown();
+    ImGui_ImplWin32_Shutdown();
+    ImGui::DestroyContext();
 
-        // 1. Show the big demo window (Most of the sample code is in ImGui::ShowDemoWindow()! You can browse its code to learn more about Dear ImGui!).
-        if (show_demo_window)
-            ImGui::ShowDemoWindow(&show_demo_window);
+    CleanupDeviceD3D();
+    ::DestroyWindow(hwnd);
+    ::UnregisterClassW(wc.lpszClassName, wc.hInstance);
 
-        // 2. Show a simple window that we create ourselves. We use a Begin/End pair to create a named window.
-        {
-            static float f = 0.0f;
-            static int counter = 0;
+    return 0;
+}
+
+bool MainLoopStep()
+{
+    // Poll and handle messages (inputs, window resize, etc.)
+    // See the WndProc() function below where we dispatch events to the imgui_impl_win32 backend.
+    bool done = false;
+    MSG msg;
+    while (::PeekMessage(&msg, NULL, 0U, 0U, PM_REMOVE))
+    {
+        ::TranslateMessage(&msg);
+        ::DispatchMessage(&msg);
+        if (msg.message == WM_QUIT)
+            done = true;
+    }
+    if (done)
+        return false;
 
-            ImGui::Begin("Hello, world!");                          // Create a window called "Hello, world!" and append into it.
+    // Start the Dear ImGui frame
+    ImGui_ImplDX10_NewFrame();
+    ImGui_ImplWin32_NewFrame();
+    ImGui::NewFrame();
 
-            ImGui::Text("This is some useful text.");               // Display some text (you can use a format strings too)
-            ImGui::Checkbox("Demo Window", &show_demo_window);      // Edit bools storing our window open/close state
-            ImGui::Checkbox("Another Window", &show_another_window);
+    // Our state
+    // (we use static, which essentially makes the variable globals, as a convenience to keep the example code easy to follow)
+    static bool show_demo_window = true;
+    static bool show_another_window = false;
+    static ImVec4 clear_color = ImVec4(0.45f, 0.55f, 0.60f, 1.00f);
 
-            ImGui::SliderFloat("float", &f, 0.0f, 1.0f);            // Edit 1 float using a slider from 0.0f to 1.0f
-            ImGui::ColorEdit3("clear color", (float*)&clear_color); // Edit 3 floats representing a color
+    // 1. Show the big demo window (Most of the sample code is in ImGui::ShowDemoWindow()! You can browse its code to learn more about Dear ImGui!).
+    if (show_demo_window)
+        ImGui::ShowDemoWindow(&show_demo_window);
 
-            if (ImGui::Button("Button"))                            // Buttons return true when clicked (most widgets return true when edited/activated)
-                counter++;
-            ImGui::SameLine();
-            ImGui::Text("counter = %d", counter);
+    // 2. Show a simple window that we create ourselves. We use a Begin/End pair to create a named window.
+    {
+        static float f = 0.0f;
+        static int counter = 0;
 
-            ImGui::Text("Application average %.3f ms/frame (%.1f FPS)", 1000.0f / ImGui::GetIO().Framerate, ImGui::GetIO().Framerate);
-            ImGui::End();
-        }
+        ImGui::Begin("Hello, world!");                          // Create a window called "Hello, world!" and append into it.
 
-        // 3. Show another simple window.
-        if (show_another_window)
-        {
-            ImGui::Begin("Another Window", &show_another_window);   // Pass a pointer to our bool variable (the window will have a closing button that will clear the bool when clicked)
-            ImGui::Text("Hello from another window!");
-            if (ImGui::Button("Close Me"))
-                show_another_window = false;
-            ImGui::End();
-        }
+        ImGui::Text("This is some useful text.");               // Display some text (you can use a format strings too)
+        ImGui::Checkbox("Demo Window", &show_demo_window);      // Edit bools storing our window open/close state
+        ImGui::Checkbox("Another Window", &show_another_window);
+
+        ImGui::SliderFloat("float", &f, 0.0f, 1.0f);            // Edit 1 float using a slider from 0.0f to 1.0f
+        ImGui::ColorEdit3("clear color", (float*)&clear_color); // Edit 3 floats representing a color
 
-        // Rendering
-        ImGui::Render();
-        const float clear_color_with_alpha[4] = { clear_color.x * clear_color.w, clear_color.y * clear_color.w, clear_color.z * clear_color.w, clear_color.w };
-        g_pd3dDevice->OMSetRenderTargets(1, &g_mainRenderTargetView, NULL);
-        g_pd3dDevice->ClearRenderTargetView(g_mainRenderTargetView, clear_color_with_alpha);
-        ImGui_ImplDX10_RenderDrawData(ImGui::GetDrawData());
+        if (ImGui::Button("Button"))                            // Buttons return true when clicked (most widgets return true when edited/activated)
+            counter++;
+        ImGui::SameLine();
+        ImGui::Text("counter = %d", counter);
 
-        g_pSwapChain->Present(1, 0); // Present with vsync
-        //g_pSwapChain->Present(0, 0); // Present without vsync
+        ImGui::Text("Application average %.3f ms/frame (%.1f FPS)", 1000.0f / ImGui::GetIO().Framerate, ImGui::GetIO().Framerate);
+        ImGui::End();
     }
 
-    ImGui_ImplDX10_Shutdown();
-    ImGui_ImplWin32_Shutdown();
-    ImGui::DestroyContext();
+    // 3. Show another simple window.
+    if (show_another_window)
+    {
+        ImGui::Begin("Another Window", &show_another_window);   // Pass a pointer to our bool variable (the window will have a closing button that will clear the bool when clicked)
+        ImGui::Text("Hello from another window!");
+        if (ImGui::Button("Close Me"))
+            show_another_window = false;
+        ImGui::End();
+    }
 
-    CleanupDeviceD3D();
-    ::DestroyWindow(hwnd);
-    ::UnregisterClassW(wc.lpszClassName, wc.hInstance);
+    // Rendering
+    ImGui::Render();
+    const float clear_color_with_alpha[4] = { clear_color.x * clear_color.w, clear_color.y * clear_color.w, clear_color.z * clear_color.w, clear_color.w };
+    g_pd3dDevice->OMSetRenderTargets(1, &g_mainRenderTargetView, NULL);
+    g_pd3dDevice->ClearRenderTargetView(g_mainRenderTargetView, clear_color_with_alpha);
+    ImGui_ImplDX10_RenderDrawData(ImGui::GetDrawData());
 
-    return 0;
+    g_pSwapChain->Present(1, 0); // Present with vsync
+    //g_pSwapChain->Present(0, 0); // Present without vsync
+
+    return true;
 }
 
 // Helper functions

examples/example_win32_directx11/main.cpp

@@ -15,6 +15,7 @@ static IDXGISwapChain*          g_pSwapChain = NULL;
 static ID3D11RenderTargetView*  g_mainRenderTargetView = NULL;
 
 // Forward declarations of helper functions
+bool MainLoopStep();
 bool CreateDeviceD3D(HWND hWnd);
 void CleanupDeviceD3D();
 void CreateRenderTarget();
@@ -73,91 +74,99 @@ int main(int, char**)
     //ImFont* font = io.Fonts->AddFontFromFileTTF("c:\\Windows\\Fonts\\ArialUni.ttf", 18.0f, NULL, io.Fonts->GetGlyphRangesJapanese());
     //IM_ASSERT(font != NULL);
 
-    // Our state
-    bool show_demo_window = true;
-    bool show_another_window = false;
-    ImVec4 clear_color = ImVec4(0.45f, 0.55f, 0.60f, 1.00f);
-
     // Main loop
-    bool done = false;
-    while (!done)
+    while (true)
     {
-        // Poll and handle messages (inputs, window resize, etc.)
-        // See the WndProc() function below for our to dispatch events to the Win32 backend.
-        MSG msg;
-        while (::PeekMessage(&msg, NULL, 0U, 0U, PM_REMOVE))
-        {
-            ::TranslateMessage(&msg);
-            ::DispatchMessage(&msg);
-            if (msg.message == WM_QUIT)
-                done = true;
-        }
-        if (done)
+        if (!MainLoopStep())
             break;
+    }
 
-        // Start the Dear ImGui frame
-        ImGui_ImplDX11_NewFrame();
-        ImGui_ImplWin32_NewFrame();
-        ImGui::NewFrame();
+    // Cleanup
+    ImGui_ImplDX11_Shutdown();
+    ImGui_ImplWin32_Shutdown();
+    ImGui::DestroyContext();
 
-        // 1. Show the big demo window (Most of the sample code is in ImGui::ShowDemoWindow()! You can browse its code to learn more about Dear ImGui!).
-        if (show_demo_window)
-            ImGui::ShowDemoWindow(&show_demo_window);
+    CleanupDeviceD3D();
+    ::DestroyWindow(hwnd);
+    ::UnregisterClassW(wc.lpszClassName, wc.hInstance);
 
-        // 2. Show a simple window that we create ourselves. We use a Begin/End pair to create a named window.
-        {
-            static float f = 0.0f;
-            static int counter = 0;
+    return 0;
+}
 
-            ImGui::Begin("Hello, world!");                          // Create a window called "Hello, world!" and append into it.
+bool MainLoopStep()
+{
+    // Poll and handle messages (inputs, window resize, etc.)
+    // See the WndProc() function below where we dispatch events to the imgui_impl_win32 backend.
+    bool done = false;
+    MSG msg;
+    while (::PeekMessage(&msg, NULL, 0U, 0U, PM_REMOVE))
+    {
+        ::TranslateMessage(&msg);
+        ::DispatchMessage(&msg);
+        if (msg.message == WM_QUIT)
+            done = true;
+    }
+    if (done)
+        return false;
 
-            ImGui::Text("This is some useful text.");               // Display some text (you can use a format strings too)
-            ImGui::Checkbox("Demo Window", &show_demo_window);      // Edit bools storing our window open/close state
-            ImGui::Checkbox("Another Window", &show_another_window);
+    // Start the Dear ImGui frame
+    ImGui_ImplDX11_NewFrame();
+    ImGui_ImplWin32_NewFrame();
+    ImGui::NewFrame();
 
-            ImGui::SliderFloat("float", &f, 0.0f, 1.0f);            // Edit 1 float using a slider from 0.0f to 1.0f
-            ImGui::ColorEdit3("clear color", (float*)&clear_color); // Edit 3 floats representing a color
+    // Our state
+    // (we use static, which essentially makes the variable globals, as a convenience to keep the example code easy to follow)
+    static bool show_demo_window = true;
+    static bool show_another_window = false;
+    static ImVec4 clear_color = ImVec4(0.45f, 0.55f, 0.60f, 1.00f);
 
-            if (ImGui::Button("Button"))                            // Buttons return true when clicked (most widgets return true when edited/activated)
-                counter++;
-            ImGui::SameLine();
-            ImGui::Text("counter = %d", counter);
+    // 1. Show the big demo window (Most of the sample code is in ImGui::ShowDemoWindow()! You can browse its code to learn more about Dear ImGui!).
+    if (show_demo_window)
+        ImGui::ShowDemoWindow(&show_demo_window);
 
-            ImGui::Text("Application average %.3f ms/frame (%.1f FPS)", 1000.0f / ImGui::GetIO().Framerate, ImGui::GetIO().Framerate);
-            ImGui::End();
-        }
+    // 2. Show a simple window that we create ourselves. We use a Begin/End pair to create a named window.
+    {
+        static float f = 0.0f;
+        static int counter = 0;
 
-        // 3. Show another simple window.
-        if (show_another_window)
-        {
-            ImGui::Begin("Another Window", &show_another_window);   // Pass a pointer to our bool variable (the window will have a closing button that will clear the bool when clicked)
-            ImGui::Text("Hello from another window!");
-            if (ImGui::Button("Close Me"))
-                show_another_window = false;
-            ImGui::End();
-        }
+        ImGui::Begin("Hello, world!");                          // Create a window called "Hello, world!" and append into it.
+
+        ImGui::Text("This is some useful text.");               // Display some text (you can use a format strings too)
+        ImGui::Checkbox("Demo Window", &show_demo_window);      // Edit bools storing our window open/close state
+        ImGui::Checkbox("Another Window", &show_another_window);
+
+        ImGui::SliderFloat("float", &f, 0.0f, 1.0f);            // Edit 1 float using a slider from 0.0f to 1.0f
+        ImGui::ColorEdit3("clear color", (float*)&clear_color); // Edit 3 floats representing a color
 
-        // Rendering
-        ImGui::Render();
-        const float clear_color_with_alpha[4] = { clear_color.x * clear_color.w, clear_color.y * clear_color.w, clear_color.z * clear_color.w, clear_color.w };
-        g_pd3dDeviceContext->OMSetRenderTargets(1, &g_mainRenderTargetView, NULL);
-        g_pd3dDeviceContext->ClearRenderTargetView(g_mainRenderTargetView, clear_color_with_alpha);
-        ImGui_ImplDX11_RenderDrawData(ImGui::GetDrawData());
+        if (ImGui::Button("Button"))                            // Buttons return true when clicked (most widgets return true when edited/activated)
+            counter++;
+        ImGui::SameLine();
+        ImGui::Text("counter = %d", counter);
 
-        g_pSwapChain->Present(1, 0); // Present with vsync
-        //g_pSwapChain->Present(0, 0); // Present without vsync
+        ImGui::Text("Application average %.3f ms/frame (%.1f FPS)", 1000.0f / ImGui::GetIO().Framerate, ImGui::GetIO().Framerate);
+        ImGui::End();
     }
 
-    // Cleanup
-    ImGui_ImplDX11_Shutdown();
-    ImGui_ImplWin32_Shutdown();
-    ImGui::DestroyContext();
+    // 3. Show another simple window.
+    if (show_another_window)
+    {
+        ImGui::Begin("Another Window", &show_another_window);   // Pass a pointer to our bool variable (the window will have a closing button that will clear the bool when clicked)
+        ImGui::Text("Hello from another window!");
+        if (ImGui::Button("Close Me"))
+            show_another_window = false;
+        ImGui::End();
+    }
 
-    CleanupDeviceD3D();
-    ::DestroyWindow(hwnd);
-    ::UnregisterClassW(wc.lpszClassName, wc.hInstance);
+    // Rendering
+    ImGui::Render();
+    const float clear_color_with_alpha[4] = { clear_color.x * clear_color.w, clear_color.y * clear_color.w, clear_color.z * clear_color.w, clear_color.w };
+    g_pd3dDeviceContext->OMSetRenderTargets(1, &g_mainRenderTargetView, NULL);
+    g_pd3dDeviceContext->ClearRenderTargetView(g_mainRenderTargetView, clear_color_with_alpha);
+    ImGui_ImplDX11_RenderDrawData(ImGui::GetDrawData());
 
-    return 0;
+    g_pSwapChain->Present(1, 0); // Present with vsync
+    //g_pSwapChain->Present(0, 0); // Present without vsync
+    return true;
 }
 
 // Helper functions

examples/example_win32_directx12/main.cpp

@@ -48,6 +48,7 @@ static ID3D12Resource*              g_mainRenderTargetResource[NUM_BACK_BUFFERS]
 static D3D12_CPU_DESCRIPTOR_HANDLE  g_mainRenderTargetDescriptor[NUM_BACK_BUFFERS] = {};
 
 // Forward declarations of helper functions
+bool MainLoopStep();
 bool CreateDeviceD3D(HWND hWnd);
 void CleanupDeviceD3D();
 void CreateRenderTarget();
@@ -111,121 +112,129 @@ int main(int, char**)
     //ImFont* font = io.Fonts->AddFontFromFileTTF("c:\\Windows\\Fonts\\ArialUni.ttf", 18.0f, NULL, io.Fonts->GetGlyphRangesJapanese());
     //IM_ASSERT(font != NULL);
 
-    // Our state
-    bool show_demo_window = true;
-    bool show_another_window = false;
-    ImVec4 clear_color = ImVec4(0.45f, 0.55f, 0.60f, 1.00f);
-
     // Main loop
-    bool done = false;
-    while (!done)
+    while (true)
     {
-        // Poll and handle messages (inputs, window resize, etc.)
-        // See the WndProc() function below for our to dispatch events to the Win32 backend.
-        MSG msg;
-        while (::PeekMessage(&msg, NULL, 0U, 0U, PM_REMOVE))
-        {
-            ::TranslateMessage(&msg);
-            ::DispatchMessage(&msg);
-            if (msg.message == WM_QUIT)
-                done = true;
-        }
-        if (done)
+        if (!MainLoopStep())
             break;
+    }
 
-        // Start the Dear ImGui frame
-        ImGui_ImplDX12_NewFrame();
-        ImGui_ImplWin32_NewFrame();
-        ImGui::NewFrame();
+    // Cleanup
+    WaitForLastSubmittedFrame();
+    ImGui_ImplDX12_Shutdown();
+    ImGui_ImplWin32_Shutdown();
+    ImGui::DestroyContext();
 
-        // 1. Show the big demo window (Most of the sample code is in ImGui::ShowDemoWindow()! You can browse its code to learn more about Dear ImGui!).
-        if (show_demo_window)
-            ImGui::ShowDemoWindow(&show_demo_window);
+    CleanupDeviceD3D();
+    ::DestroyWindow(hwnd);
+    ::UnregisterClassW(wc.lpszClassName, wc.hInstance);
 
-        // 2. Show a simple window that we create ourselves. We use a Begin/End pair to create a named window.
-        {
-            static float f = 0.0f;
-            static int counter = 0;
+    return 0;
+}
 
-            ImGui::Begin("Hello, world!");                          // Create a window called "Hello, world!" and append into it.
+bool MainLoopStep()
+{
+    // Poll and handle messages (inputs, window resize, etc.)
+    // See the WndProc() function below where we dispatch events to the imgui_impl_win32 backend.
+    bool done = false;
+    MSG msg;
+    while (::PeekMessage(&msg, NULL, 0U, 0U, PM_REMOVE))
+    {
+        ::TranslateMessage(&msg);
+        ::DispatchMessage(&msg);
+        if (msg.message == WM_QUIT)
+            done = true;
+    }
+    if (done)
+        return false;
 
-            ImGui::Text("This is some useful text.");               // Display some text (you can use a format strings too)
-            ImGui::Checkbox("Demo Window", &show_demo_window);      // Edit bools storing our window open/close state
-            ImGui::Checkbox("Another Window", &show_another_window);
+    // Start the Dear ImGui frame
+    ImGui_ImplDX12_NewFrame();
+    ImGui_ImplWin32_NewFrame();
+    ImGui::NewFrame();
 
-            ImGui::SliderFloat("float", &f, 0.0f, 1.0f);            // Edit 1 float using a slider from 0.0f to 1.0f
-            ImGui::ColorEdit3("clear color", (float*)&clear_color); // Edit 3 floats representing a color
+    // Our state
+    // (we use static, which essentially makes the variable globals, as a convenience to keep the example code easy to follow)
+    static bool show_demo_window = true;
+    static bool show_another_window = false;
+    static ImVec4 clear_color = ImVec4(0.45f, 0.55f, 0.60f, 1.00f);
 
-            if (ImGui::Button("Button"))                            // Buttons return true when clicked (most widgets return true when edited/activated)
-                counter++;
-            ImGui::SameLine();
-            ImGui::Text("counter = %d", counter);
+    // 1. Show the big demo window (Most of the sample code is in ImGui::ShowDemoWindow()! You can browse its code to learn more about Dear ImGui!).
+    if (show_demo_window)
+        ImGui::ShowDemoWindow(&show_demo_window);
 
-            ImGui::Text("Application average %.3f ms/frame (%.1f FPS)", 1000.0f / ImGui::GetIO().Framerate, ImGui::GetIO().Framerate);
-            ImGui::End();
-        }
+    // 2. Show a simple window that we create ourselves. We use a Begin/End pair to create a named window.
+    {
+        static float f = 0.0f;
+        static int counter = 0;
 
-        // 3. Show another simple window.
-        if (show_another_window)
-        {
-            ImGui::Begin("Another Window", &show_another_window);   // Pass a pointer to our bool variable (the window will have a closing button that will clear the bool when clicked)
-            ImGui::Text("Hello from another window!");
-            if (ImGui::Button("Close Me"))
-                show_another_window = false;
-            ImGui::End();
-        }
+        ImGui::Begin("Hello, world!");                          // Create a window called "Hello, world!" and append into it.
 
-        // Rendering
-        ImGui::Render();
-
-        FrameContext* frameCtx = WaitForNextFrameResources();
-        UINT backBufferIdx = g_pSwapChain->GetCurrentBackBufferIndex();
-        frameCtx->CommandAllocator->Reset();
-
-        D3D12_RESOURCE_BARRIER barrier = {};
-        barrier.Type                   = D3D12_RESOURCE_BARRIER_TYPE_TRANSITION;
-        barrier.Flags                  = D3D12_RESOURCE_BARRIER_FLAG_NONE;
-        barrier.Transition.pResource   = g_mainRenderTargetResource[backBufferIdx];
-        barrier.Transition.Subresource = D3D12_RESOURCE_BARRIER_ALL_SUBRESOURCES;
-        barrier.Transition.StateBefore = D3D12_RESOURCE_STATE_PRESENT;
-        barrier.Transition.StateAfter  = D3D12_RESOURCE_STATE_RENDER_TARGET;
-        g_pd3dCommandList->Reset(frameCtx->CommandAllocator, NULL);
-        g_pd3dCommandList->ResourceBarrier(1, &barrier);
-
-        // Render Dear ImGui graphics
-        const float clear_color_with_alpha[4] = { clear_color.x * clear_color.w, clear_color.y * clear_color.w, clear_color.z * clear_color.w, clear_color.w };
-        g_pd3dCommandList->ClearRenderTargetView(g_mainRenderTargetDescriptor[backBufferIdx], clear_color_with_alpha, 0, NULL);
-        g_pd3dCommandList->OMSetRenderTargets(1, &g_mainRenderTargetDescriptor[backBufferIdx], FALSE, NULL);
-        g_pd3dCommandList->SetDescriptorHeaps(1, &g_pd3dSrvDescHeap);
-        ImGui_ImplDX12_RenderDrawData(ImGui::GetDrawData(), g_pd3dCommandList);
-        barrier.Transition.StateBefore = D3D12_RESOURCE_STATE_RENDER_TARGET;
-        barrier.Transition.StateAfter  = D3D12_RESOURCE_STATE_PRESENT;
-        g_pd3dCommandList->ResourceBarrier(1, &barrier);
-        g_pd3dCommandList->Close();
-
-        g_pd3dCommandQueue->ExecuteCommandLists(1, (ID3D12CommandList* const*)&g_pd3dCommandList);
-
-        g_pSwapChain->Present(1, 0); // Present with vsync
-        //g_pSwapChain->Present(0, 0); // Present without vsync
-
-        UINT64 fenceValue = g_fenceLastSignaledValue + 1;
-        g_pd3dCommandQueue->Signal(g_fence, fenceValue);
-        g_fenceLastSignaledValue = fenceValue;
-        frameCtx->FenceValue = fenceValue;
-    }
+        ImGui::Text("This is some useful text.");               // Display some text (you can use a format strings too)
+        ImGui::Checkbox("Demo Window", &show_demo_window);      // Edit bools storing our window open/close state
+        ImGui::Checkbox("Another Window", &show_another_window);
 
-    WaitForLastSubmittedFrame();
+        ImGui::SliderFloat("float", &f, 0.0f, 1.0f);            // Edit 1 float using a slider from 0.0f to 1.0f
+        ImGui::ColorEdit3("clear color", (float*)&clear_color); // Edit 3 floats representing a color
 
-    // Cleanup
-    ImGui_ImplDX12_Shutdown();
-    ImGui_ImplWin32_Shutdown();
-    ImGui::DestroyContext();
+        if (ImGui::Button("Button"))                            // Buttons return true when clicked (most widgets return true when edited/activated)
+            counter++;
+        ImGui::SameLine();
+        ImGui::Text("counter = %d", counter);
 
-    CleanupDeviceD3D();
-    ::DestroyWindow(hwnd);
-    ::UnregisterClassW(wc.lpszClassName, wc.hInstance);
+        ImGui::Text("Application average %.3f ms/frame (%.1f FPS)", 1000.0f / ImGui::GetIO().Framerate, ImGui::GetIO().Framerate);
+        ImGui::End();
+    }
 
-    return 0;
+    // 3. Show another simple window.
+    if (show_another_window)
+    {
+        ImGui::Begin("Another Window", &show_another_window);   // Pass a pointer to our bool variable (the window will have a closing button that will clear the bool when clicked)
+        ImGui::Text("Hello from another window!");
+        if (ImGui::Button("Close Me"))
+            show_another_window = false;
+        ImGui::End();
+    }
+
+    // Rendering
+    ImGui::Render();
+
+    FrameContext* frameCtx = WaitForNextFrameResources();
+    UINT backBufferIdx = g_pSwapChain->GetCurrentBackBufferIndex();
+    frameCtx->CommandAllocator->Reset();
+
+    D3D12_RESOURCE_BARRIER barrier = {};
+    barrier.Type = D3D12_RESOURCE_BARRIER_TYPE_TRANSITION;
+    barrier.Flags = D3D12_RESOURCE_BARRIER_FLAG_NONE;
+    barrier.Transition.pResource = g_mainRenderTargetResource[backBufferIdx];
+    barrier.Transition.Subresource = D3D12_RESOURCE_BARRIER_ALL_SUBRESOURCES;
+    barrier.Transition.StateBefore = D3D12_RESOURCE_STATE_PRESENT;
+    barrier.Transition.StateAfter = D3D12_RESOURCE_STATE_RENDER_TARGET;
+    g_pd3dCommandList->Reset(frameCtx->CommandAllocator, NULL);
+    g_pd3dCommandList->ResourceBarrier(1, &barrier);
+
+    // Render Dear ImGui graphics
+    const float clear_color_with_alpha[4] = { clear_color.x * clear_color.w, clear_color.y * clear_color.w, clear_color.z * clear_color.w, clear_color.w };
+    g_pd3dCommandList->ClearRenderTargetView(g_mainRenderTargetDescriptor[backBufferIdx], clear_color_with_alpha, 0, NULL);
+    g_pd3dCommandList->OMSetRenderTargets(1, &g_mainRenderTargetDescriptor[backBufferIdx], FALSE, NULL);
+    g_pd3dCommandList->SetDescriptorHeaps(1, &g_pd3dSrvDescHeap);
+    ImGui_ImplDX12_RenderDrawData(ImGui::GetDrawData(), g_pd3dCommandList);
+    barrier.Transition.StateBefore = D3D12_RESOURCE_STATE_RENDER_TARGET;
+    barrier.Transition.StateAfter = D3D12_RESOURCE_STATE_PRESENT;
+    g_pd3dCommandList->ResourceBarrier(1, &barrier);
+    g_pd3dCommandList->Close();
+
+    g_pd3dCommandQueue->ExecuteCommandLists(1, (ID3D12CommandList* const*)&g_pd3dCommandList);
+
+    g_pSwapChain->Present(1, 0); // Present with vsync
+    //g_pSwapChain->Present(0, 0); // Present without vsync
+
+    UINT64 fenceValue = g_fenceLastSignaledValue + 1;
+    g_pd3dCommandQueue->Signal(g_fence, fenceValue);
+    g_fenceLastSignaledValue = fenceValue;
+    frameCtx->FenceValue = fenceValue;
+
+    return true;
 }
 
 // Helper functions

examples/example_win32_directx9/main.cpp

@@ -14,6 +14,7 @@ static LPDIRECT3DDEVICE9        g_pd3dDevice = NULL;
 static D3DPRESENT_PARAMETERS    g_d3dpp = {};
 
 // Forward declarations of helper functions
+bool MainLoopStep();
 bool CreateDeviceD3D(HWND hWnd);
 void CleanupDeviceD3D();
 void ResetDevice();
@@ -71,99 +72,109 @@ int main(int, char**)
     //ImFont* font = io.Fonts->AddFontFromFileTTF("c:\\Windows\\Fonts\\ArialUni.ttf", 18.0f, NULL, io.Fonts->GetGlyphRangesJapanese());
     //IM_ASSERT(font != NULL);
 
-    // Our state
-    bool show_demo_window = true;
-    bool show_another_window = false;
-    ImVec4 clear_color = ImVec4(0.45f, 0.55f, 0.60f, 1.00f);
-
     // Main loop
-    bool done = false;
-    while (!done)
+    while (true)
     {
-        // Poll and handle messages (inputs, window resize, etc.)
-        // See the WndProc() function below for our to dispatch events to the Win32 backend.
-        MSG msg;
-        while (::PeekMessage(&msg, NULL, 0U, 0U, PM_REMOVE))
-        {
-            ::TranslateMessage(&msg);
-            ::DispatchMessage(&msg);
-            if (msg.message == WM_QUIT)
-                done = true;
-        }
-        if (done)
+        if (!MainLoopStep())
             break;
+    }
 
-        // Start the Dear ImGui frame
-        ImGui_ImplDX9_NewFrame();
-        ImGui_ImplWin32_NewFrame();
-        ImGui::NewFrame();
+    // Cleanup
+    ImGui_ImplDX9_Shutdown();
+    ImGui_ImplWin32_Shutdown();
+    ImGui::DestroyContext();
 
-        // 1. Show the big demo window (Most of the sample code is in ImGui::ShowDemoWindow()! You can browse its code to learn more about Dear ImGui!).
-        if (show_demo_window)
-            ImGui::ShowDemoWindow(&show_demo_window);
+    CleanupDeviceD3D();
+    ::DestroyWindow(hwnd);
+    ::UnregisterClassW(wc.lpszClassName, wc.hInstance);
 
-        // 2. Show a simple window that we create ourselves. We use a Begin/End pair to create a named window.
-        {
-            static float f = 0.0f;
-            static int counter = 0;
+    return 0;
+}
 
-            ImGui::Begin("Hello, world!");                          // Create a window called "Hello, world!" and append into it.
+bool MainLoopStep()
+{
+    // Poll and handle messages (inputs, window resize, etc.)
+    // See the WndProc() function below where we dispatch events to the imgui_impl_win32 backend.
+    bool done = false;
+    MSG msg;
+    while (::PeekMessage(&msg, NULL, 0U, 0U, PM_REMOVE))
+    {
+        ::TranslateMessage(&msg);
+        ::DispatchMessage(&msg);
+        if (msg.message == WM_QUIT)
+            done = true;
+    }
+    if (done)
+        return false;
 
-            ImGui::Text("This is some useful text.");               // Display some text (you can use a format strings too)
-            ImGui::Checkbox("Demo Window", &show_demo_window);      // Edit bools storing our window open/close state
-            ImGui::Checkbox("Another Window", &show_another_window);
+    // Start the Dear ImGui frame
+    ImGui_ImplDX9_NewFrame();
+    ImGui_ImplWin32_NewFrame();
+    ImGui::NewFrame();
 
-            ImGui::SliderFloat("float", &f, 0.0f, 1.0f);            // Edit 1 float using a slider from 0.0f to 1.0f
-            ImGui::ColorEdit3("clear color", (float*)&clear_color); // Edit 3 floats representing a color
+    // Our state
+    // (we use static, which essentially makes the variable globals, as a convenience to keep the example code easy to follow)
+    static bool show_demo_window = true;
+    static bool show_another_window = false;
+    static ImVec4 clear_color = ImVec4(0.45f, 0.55f, 0.60f, 1.00f);
 
-            if (ImGui::Button("Button"))                            // Buttons return true when clicked (most widgets return true when edited/activated)
-                counter++;
-            ImGui::SameLine();
-            ImGui::Text("counter = %d", counter);
+    // 1. Show the big demo window (Most of the sample code is in ImGui::ShowDemoWindow()! You can browse its code to learn more about Dear ImGui!).
+    if (show_demo_window)
+        ImGui::ShowDemoWindow(&show_demo_window);
 
-            ImGui::Text("Application average %.3f ms/frame (%.1f FPS)", 1000.0f / ImGui::GetIO().Framerate, ImGui::GetIO().Framerate);
-            ImGui::End();
-        }
+    // 2. Show a simple window that we create ourselves. We use a Begin/End pair to create a named window.
+    {
+        static float f = 0.0f;
+        static int counter = 0;
 
-        // 3. Show another simple window.
-        if (show_another_window)
-        {
-            ImGui::Begin("Another Window", &show_another_window);   // Pass a pointer to our bool variable (the window will have a closing button that will clear the bool when clicked)
-            ImGui::Text("Hello from another window!");
-            if (ImGui::Button("Close Me"))
-                show_another_window = false;
-            ImGui::End();
-        }
+        ImGui::Begin("Hello, world!");                          // Create a window called "Hello, world!" and append into it.
 
-        // Rendering
-        ImGui::EndFrame();
-        g_pd3dDevice->SetRenderState(D3DRS_ZENABLE, FALSE);
-        g_pd3dDevice->SetRenderState(D3DRS_ALPHABLENDENABLE, FALSE);
-        g_pd3dDevice->SetRenderState(D3DRS_SCISSORTESTENABLE, FALSE);
-        D3DCOLOR clear_col_dx = D3DCOLOR_RGBA((int)(clear_color.x*clear_color.w*255.0f), (int)(clear_color.y*clear_color.w*255.0f), (int)(clear_color.z*clear_color.w*255.0f), (int)(clear_color.w*255.0f));
-        g_pd3dDevice->Clear(0, NULL, D3DCLEAR_TARGET | D3DCLEAR_ZBUFFER, clear_col_dx, 1.0f, 0);
-        if (g_pd3dDevice->BeginScene() >= 0)
-        {
-            ImGui::Render();
-            ImGui_ImplDX9_RenderDrawData(ImGui::GetDrawData());
-            g_pd3dDevice->EndScene();
-        }
-        HRESULT result = g_pd3dDevice->Present(NULL, NULL, NULL, NULL);
+        ImGui::Text("This is some useful text.");               // Display some text (you can use a format strings too)
+        ImGui::Checkbox("Demo Window", &show_demo_window);      // Edit bools storing our window open/close state
+        ImGui::Checkbox("Another Window", &show_another_window);
 
-        // Handle loss of D3D9 device
-        if (result == D3DERR_DEVICELOST && g_pd3dDevice->TestCooperativeLevel() == D3DERR_DEVICENOTRESET)
-            ResetDevice();
+        ImGui::SliderFloat("float", &f, 0.0f, 1.0f);            // Edit 1 float using a slider from 0.0f to 1.0f
+        ImGui::ColorEdit3("clear color", (float*)&clear_color); // Edit 3 floats representing a color
+
+        if (ImGui::Button("Button"))                            // Buttons return true when clicked (most widgets return true when edited/activated)
+            counter++;
+        ImGui::SameLine();
+        ImGui::Text("counter = %d", counter);
+
+        ImGui::Text("Application average %.3f ms/frame (%.1f FPS)", 1000.0f / ImGui::GetIO().Framerate, ImGui::GetIO().Framerate);
+        ImGui::End();
     }
 
-    ImGui_ImplDX9_Shutdown();
-    ImGui_ImplWin32_Shutdown();
-    ImGui::DestroyContext();
+    // 3. Show another simple window.
+    if (show_another_window)
+    {
+        ImGui::Begin("Another Window", &show_another_window);   // Pass a pointer to our bool variable (the window will have a closing button that will clear the bool when clicked)
+        ImGui::Text("Hello from another window!");
+        if (ImGui::Button("Close Me"))
+            show_another_window = false;
+        ImGui::End();
+    }
 
-    CleanupDeviceD3D();
-    ::DestroyWindow(hwnd);
-    ::UnregisterClassW(wc.lpszClassName, wc.hInstance);
+    // Rendering
+    ImGui::EndFrame();
+    g_pd3dDevice->SetRenderState(D3DRS_ZENABLE, FALSE);
+    g_pd3dDevice->SetRenderState(D3DRS_ALPHABLENDENABLE, FALSE);
+    g_pd3dDevice->SetRenderState(D3DRS_SCISSORTESTENABLE, FALSE);
+    D3DCOLOR clear_col_dx = D3DCOLOR_RGBA((int)(clear_color.x * clear_color.w * 255.0f), (int)(clear_color.y * clear_color.w * 255.0f), (int)(clear_color.z * clear_color.w * 255.0f), (int)(clear_color.w * 255.0f));
+    g_pd3dDevice->Clear(0, NULL, D3DCLEAR_TARGET | D3DCLEAR_ZBUFFER, clear_col_dx, 1.0f, 0);
+    if (g_pd3dDevice->BeginScene() >= 0)
+    {
+        ImGui::Render();
+        ImGui_ImplDX9_RenderDrawData(ImGui::GetDrawData());
+        g_pd3dDevice->EndScene();
+    }
+    HRESULT result = g_pd3dDevice->Present(NULL, NULL, NULL, NULL);
 
-    return 0;
+    // Handle loss of D3D9 device
+    if (result == D3DERR_DEVICELOST && g_pd3dDevice->TestCooperativeLevel() == D3DERR_DEVICENOTRESET)
+        ResetDevice();
+
+    return true;
 }
 
 // Helper functions