Merge branch 'vulkan_fix_master' into vulkan_fix_docking

# Conflicts:
#	examples/imgui_impl_vulkan.cpp

docs/CHANGELOG.txt

@@ -98,6 +98,15 @@ Other changes:
 -----------------------------------------------------------------------
 
 Breaking Changes:
+- Examples: Vulkan: Added extra parameter to ImGui_ImplVulkan_RenderDrawData(). Engine/app is
+  in charge of owning/storing 1 ImGui_ImplVulkan_FrameRenderBuffers per in-flight rendering frame.
+  (The demo helper ImGui_ImplVulkanH_Window structure carries them.) (#2461, #2348, #2378, #2097)
+- Examples: Vulkan: Added MinImageCount field in ImGui_ImplVulkan_InitInfo, required during
+  initialization to specify the number of in-flight image requested by swap chains.
+  (was previously a hard #define IMGUI_VK_QUEUED_FRAMES 2). (#2071, #1677) [@nathanvoglsam]
+- Examples: Vulkan: Tidying up the demo/internals helpers (most engine/app should not rely
+  on them but it is possible you have!).
+
 
 Other Changes:
 - InputText: Fixed selection background starts rendering one frame after the cursor movement

examples/example_glfw_vulkan/main.cpp

@@ -1,6 +1,13 @@
 // dear imgui: standalone example application for Glfw + Vulkan
 // If you are new to dear imgui, see examples/README.txt and documentation at the top of imgui.cpp.
 
+// Important note to the reader who wish to integrate imgui_impl_vulkan.cpp/.h in their own engine/app.
+// - Common ImGui_ImplVulkan_XXXX functions and structures are used to interface with imgui_impl_vulkan.cpp/.h.
+//   You will use those if you want to use this rendering back-end in your engine/app.
+// - Helper ImGui_ImplVulkanH_XXXX functions and structures are only used by this example (main.cpp) and by 
+//   the back-end itself (imgui_impl_vulkan.cpp), but should PROBABLY NOT be used by your own engine/app code.
+// Read comments in imgui_impl_vulkan.h.
+
 #include "imgui.h"
 #include "imgui_impl_glfw.h"
 #include "imgui_impl_vulkan.h"
@@ -23,19 +30,21 @@
 #define IMGUI_VULKAN_DEBUG_REPORT
 #endif
 
-static VkAllocationCallbacks*       g_Allocator = NULL;
-static VkInstance                   g_Instance = VK_NULL_HANDLE;
-static VkPhysicalDevice             g_PhysicalDevice = VK_NULL_HANDLE;
-static VkDevice                     g_Device = VK_NULL_HANDLE;
-static uint32_t                     g_QueueFamily = (uint32_t)-1;
-static VkQueue                      g_Queue = VK_NULL_HANDLE;
-static VkDebugReportCallbackEXT     g_DebugReport = VK_NULL_HANDLE;
-static VkPipelineCache              g_PipelineCache = VK_NULL_HANDLE;
-static VkDescriptorPool             g_DescriptorPool = VK_NULL_HANDLE;
-
-static ImGui_ImplVulkanH_WindowData g_WindowData;
-static bool                         g_ResizeWanted = false;
-static int                          g_ResizeWidth = 0, g_ResizeHeight = 0;
+static VkAllocationCallbacks*   g_Allocator = NULL;
+static VkInstance               g_Instance = VK_NULL_HANDLE;
+static VkPhysicalDevice         g_PhysicalDevice = VK_NULL_HANDLE;
+static VkDevice                 g_Device = VK_NULL_HANDLE;
+static uint32_t                 g_QueueFamily = (uint32_t)-1;
+static VkQueue                  g_Queue = VK_NULL_HANDLE;
+static VkDebugReportCallbackEXT g_DebugReport = VK_NULL_HANDLE;
+static VkPipelineCache          g_PipelineCache = VK_NULL_HANDLE;
+static VkDescriptorPool         g_DescriptorPool = VK_NULL_HANDLE;
+
+static ImGui_ImplVulkanH_Window g_WindowData;
+static int                      g_MinImageCount = 2;
+static bool                     g_SwapChainRebuild = false;
+static int                      g_SwapChainResizeWidth = 0;
+static int                      g_SwapChainResizeHeight = 0;
 
 static void check_vk_result(VkResult err)
 {
@@ -107,6 +116,7 @@ static void SetupVulkan(const char** extensions, uint32_t extensions_count)
         uint32_t gpu_count;
         err = vkEnumeratePhysicalDevices(g_Instance, &gpu_count, NULL);
         check_vk_result(err);
+        IM_ASSERT(gpu_count > 0);
 
         VkPhysicalDevice* gpus = (VkPhysicalDevice*)malloc(sizeof(VkPhysicalDevice) * gpu_count);
         err = vkEnumeratePhysicalDevices(g_Instance, &gpu_count, gpus);
@@ -183,7 +193,7 @@ static void SetupVulkan(const char** extensions, uint32_t extensions_count)
     }
 }
 
-static void SetupVulkanWindowData(ImGui_ImplVulkanH_WindowData* wd, VkSurfaceKHR surface, int width, int height)
+static void SetupVulkanWindow(ImGui_ImplVulkanH_Window* wd, VkSurfaceKHR surface, int width, int height)
 {
     wd->Surface = surface;
 
@@ -211,14 +221,12 @@ static void SetupVulkanWindowData(ImGui_ImplVulkanH_WindowData* wd, VkSurfaceKHR
     //printf("[vulkan] Selected PresentMode = %d\n", wd->PresentMode);
 
     // Create SwapChain, RenderPass, Framebuffer, etc.
-    ImGui_ImplVulkanH_CreateWindowDataCommandBuffers(g_PhysicalDevice, g_Device, g_QueueFamily, wd, g_Allocator);
-    ImGui_ImplVulkanH_CreateWindowDataSwapChainAndFramebuffer(g_PhysicalDevice, g_Device, wd, g_Allocator, width, height);
+    IM_ASSERT(g_MinImageCount >= 2);
+    ImGui_ImplVulkanH_CreateWindow(g_Instance, g_PhysicalDevice, g_Device, wd, g_QueueFamily, g_Allocator, width, height, g_MinImageCount);
 }
 
 static void CleanupVulkan()
 {
-    ImGui_ImplVulkanH_WindowData* wd = &g_WindowData;
-    ImGui_ImplVulkanH_DestroyWindowData(g_Instance, g_Device, wd, g_Allocator);
     vkDestroyDescriptorPool(g_Device, g_DescriptorPool, g_Allocator);
 
 #ifdef IMGUI_VULKAN_DEBUG_REPORT
@@ -231,7 +239,16 @@ static void CleanupVulkan()
     vkDestroyInstance(g_Instance, g_Allocator);
 }
 
-static void FrameRender(ImGui_ImplVulkanH_WindowData* wd)
+static void CleanupVulkanWindow()
+{
+    // In a normal engine/app integration, you wouldn't use the ImGui_ImplVulkanH_Window helpers,
+    // however you would instead need to call ImGui_ImplVulkan_DestroyFrameRenderBuffers() on each 
+    // ImGui_ImplVulkan_FrameRenderBuffers structure that you own.
+    ImGui_ImplVulkanH_Window* wd = &g_WindowData;
+    ImGui_ImplVulkanH_DestroyWindow(g_Instance, g_Device, wd, g_Allocator);
+}
+
+static void FrameRender(ImGui_ImplVulkanH_Window* wd)
 {
     VkResult err;
 
@@ -239,7 +256,7 @@ static void FrameRender(ImGui_ImplVulkanH_WindowData* wd)
     err = vkAcquireNextImageKHR(g_Device, wd->Swapchain, UINT64_MAX, image_acquired_semaphore, VK_NULL_HANDLE, &wd->FrameIndex);
     check_vk_result(err);
 
-    ImGui_ImplVulkanH_FrameData* fd = &wd->Frames[wd->FrameIndex];
+    ImGui_ImplVulkanH_Frame* fd = &wd->Frames[wd->FrameIndex];
     {
         err = vkWaitForFences(g_Device, 1, &fd->Fence, VK_TRUE, UINT64_MAX);    // wait indefinitely instead of periodically checking
         check_vk_result(err);
@@ -260,7 +277,7 @@ static void FrameRender(ImGui_ImplVulkanH_WindowData* wd)
         VkRenderPassBeginInfo info = {};
         info.sType = VK_STRUCTURE_TYPE_RENDER_PASS_BEGIN_INFO;
         info.renderPass = wd->RenderPass;
-        info.framebuffer = wd->Framebuffer[wd->FrameIndex];
+        info.framebuffer = fd->Framebuffer;
         info.renderArea.extent.width = wd->Width;
         info.renderArea.extent.height = wd->Height;
         info.clearValueCount = 1;
@@ -269,7 +286,7 @@ static void FrameRender(ImGui_ImplVulkanH_WindowData* wd)
     }
 
     // Record Imgui Draw Data and draw funcs into command buffer
-    ImGui_ImplVulkan_RenderDrawData(ImGui::GetDrawData(), fd->CommandBuffer);
+    ImGui_ImplVulkan_RenderDrawData(ImGui::GetDrawData(), fd->CommandBuffer, &fd->RenderBuffers);
 
     // Submit command buffer
     vkCmdEndRenderPass(fd->CommandBuffer);
@@ -292,9 +309,9 @@ static void FrameRender(ImGui_ImplVulkanH_WindowData* wd)
     }
 }
 
-static void FramePresent(ImGui_ImplVulkanH_WindowData* wd)
+static void FramePresent(ImGui_ImplVulkanH_Window* wd)
 {
-    ImGui_ImplVulkanH_FrameData* fd = &wd->Frames[wd->FrameIndex];
+    ImGui_ImplVulkanH_Frame* fd = &wd->Frames[wd->FrameIndex];
     VkPresentInfoKHR info = {};
     info.sType = VK_STRUCTURE_TYPE_PRESENT_INFO_KHR;
     info.waitSemaphoreCount = 1;
@@ -313,14 +330,14 @@ static void glfw_error_callback(int error, const char* description)
 
 static void glfw_resize_callback(GLFWwindow*, int w, int h)
 {
-    g_ResizeWanted = true;
-    g_ResizeWidth = w;
-    g_ResizeHeight = h;
+    g_SwapChainRebuild = true;
+    g_SwapChainResizeWidth = w;
+    g_SwapChainResizeHeight = h;
 }
 
 int main(int, char**)
 {
-    // Setup window
+    // Setup GLFW window
     glfwSetErrorCallback(glfw_error_callback);
     if (!glfwInit())
         return 1;
@@ -347,8 +364,8 @@ int main(int, char**)
     int w, h;
     glfwGetFramebufferSize(window, &w, &h);
     glfwSetFramebufferSizeCallback(window, glfw_resize_callback);
-    ImGui_ImplVulkanH_WindowData* wd = &g_WindowData;
-    SetupVulkanWindowData(wd, surface, w, h);
+    ImGui_ImplVulkanH_Window* wd = &g_WindowData;
+    SetupVulkanWindow(wd, surface, w, h);
 
     // Setup Dear ImGui context
     IMGUI_CHECKVERSION();
@@ -384,6 +401,7 @@ int main(int, char**)
     init_info.PipelineCache = g_PipelineCache;
     init_info.DescriptorPool = g_DescriptorPool;
     init_info.Allocator = g_Allocator;
+    init_info.MinImageCount = g_MinImageCount;
     init_info.CheckVkResultFn = check_vk_result;
     ImGui_ImplVulkan_Init(&init_info, wd->RenderPass);
 
@@ -429,7 +447,7 @@ int main(int, char**)
 
         err = vkDeviceWaitIdle(g_Device);
         check_vk_result(err);
-        ImGui_ImplVulkan_InvalidateFontUploadObjects();
+        ImGui_ImplVulkan_DestroyFontUploadObjects();
     }
 
     bool show_demo_window = true;
@@ -445,10 +463,13 @@ int main(int, char**)
         // - When io.WantCaptureKeyboard is true, do not dispatch keyboard input data to your main application.
         // Generally you may always pass all inputs to dear imgui, and hide them from your application based on those two flags.
         glfwPollEvents();
-        if (g_ResizeWanted)
+
+        if (g_SwapChainRebuild)
         {
-            ImGui_ImplVulkanH_CreateWindowDataSwapChainAndFramebuffer(g_PhysicalDevice, g_Device, &g_WindowData, g_Allocator, g_ResizeWidth, g_ResizeHeight);
-            g_ResizeWanted = false;
+            g_SwapChainRebuild = false;
+            ImGui_ImplVulkanH_CreateWindow(g_Instance, g_PhysicalDevice, g_Device, &g_WindowData, g_QueueFamily, g_Allocator, g_SwapChainResizeWidth, g_SwapChainResizeHeight, g_MinImageCount);
+            ImGui_ImplVulkan_SetSwapChainMinImageCount(g_MinImageCount);
+            g_WindowData.FrameIndex = 0;
         }
 
         // Start the Dear ImGui frame
@@ -514,6 +535,8 @@ int main(int, char**)
     ImGui_ImplVulkan_Shutdown();
     ImGui_ImplGlfw_Shutdown();
     ImGui::DestroyContext();
+
+    CleanupVulkanWindow();
     CleanupVulkan();
 
     glfwDestroyWindow(window);

examples/example_sdl_vulkan/main.cpp

@@ -1,6 +1,13 @@
 // dear imgui: standalone example application for SDL2 + Vulkan
 // If you are new to dear imgui, see examples/README.txt and documentation at the top of imgui.cpp.
 
+// Important note to the reader who wish to integrate imgui_impl_vulkan.cpp/.h in their own engine/app.
+// - Common ImGui_ImplVulkan_XXXX functions and structures are used to interface with imgui_impl_vulkan.cpp/.h.
+//   You will use those if you want to use this rendering back-end in your engine/app.
+// - Helper ImGui_ImplVulkanH_XXXX functions and structures are only used by this example (main.cpp) and by 
+//   the back-end itself (imgui_impl_vulkan.cpp), but should PROBABLY NOT be used by your own engine/app code.
+// Read comments in imgui_impl_vulkan.h.
+
 #include "imgui.h"
 #include "imgui_impl_sdl.h"
 #include "imgui_impl_vulkan.h"
@@ -15,17 +22,21 @@
 #define IMGUI_VULKAN_DEBUG_REPORT
 #endif
 
-static VkAllocationCallbacks*       g_Allocator = NULL;
-static VkInstance                   g_Instance = VK_NULL_HANDLE;
-static VkPhysicalDevice             g_PhysicalDevice = VK_NULL_HANDLE;
-static VkDevice                     g_Device = VK_NULL_HANDLE;
-static uint32_t                     g_QueueFamily = (uint32_t)-1;
-static VkQueue                      g_Queue = VK_NULL_HANDLE;
-static VkDebugReportCallbackEXT     g_DebugReport = VK_NULL_HANDLE;
-static VkPipelineCache              g_PipelineCache = VK_NULL_HANDLE;
-static VkDescriptorPool             g_DescriptorPool = VK_NULL_HANDLE;
-
-static ImGui_ImplVulkanH_WindowData g_WindowData;
+static VkAllocationCallbacks*   g_Allocator = NULL;
+static VkInstance               g_Instance = VK_NULL_HANDLE;
+static VkPhysicalDevice         g_PhysicalDevice = VK_NULL_HANDLE;
+static VkDevice                 g_Device = VK_NULL_HANDLE;
+static uint32_t                 g_QueueFamily = (uint32_t)-1;
+static VkQueue                  g_Queue = VK_NULL_HANDLE;
+static VkDebugReportCallbackEXT g_DebugReport = VK_NULL_HANDLE;
+static VkPipelineCache          g_PipelineCache = VK_NULL_HANDLE;
+static VkDescriptorPool         g_DescriptorPool = VK_NULL_HANDLE;
+
+static ImGui_ImplVulkanH_Window g_WindowData;
+static uint32_t                 g_MinImageCount = 2;
+static bool                     g_SwapChainRebuild = false;
+static int                      g_SwapChainResizeWidth = 0;
+static int                      g_SwapChainResizeHeight = 0;
 
 static void check_vk_result(VkResult err)
 {
@@ -97,6 +108,7 @@ static void SetupVulkan(const char** extensions, uint32_t extensions_count)
         uint32_t gpu_count;
         err = vkEnumeratePhysicalDevices(g_Instance, &gpu_count, NULL);
         check_vk_result(err);
+        IM_ASSERT(gpu_count > 0);
 
         VkPhysicalDevice* gpus = (VkPhysicalDevice*)malloc(sizeof(VkPhysicalDevice) * gpu_count);
         err = vkEnumeratePhysicalDevices(g_Instance, &gpu_count, gpus);
@@ -173,7 +185,7 @@ static void SetupVulkan(const char** extensions, uint32_t extensions_count)
     }
 }
 
-static void SetupVulkanWindowData(ImGui_ImplVulkanH_WindowData* wd, VkSurfaceKHR surface, int width, int height)
+static void SetupVulkanWindow(ImGui_ImplVulkanH_Window* wd, VkSurfaceKHR surface, int width, int height)
 {
     wd->Surface = surface;
 
@@ -201,14 +213,12 @@ static void SetupVulkanWindowData(ImGui_ImplVulkanH_WindowData* wd, VkSurfaceKHR
     //printf("[vulkan] Selected PresentMode = %d\n", wd->PresentMode);
 
     // Create SwapChain, RenderPass, Framebuffer, etc.
-    ImGui_ImplVulkanH_CreateWindowDataCommandBuffers(g_PhysicalDevice, g_Device, g_QueueFamily, wd, g_Allocator);
-    ImGui_ImplVulkanH_CreateWindowDataSwapChainAndFramebuffer(g_PhysicalDevice, g_Device, wd, g_Allocator, width, height);
+    IM_ASSERT(g_MinImageCount >= 2);
+    ImGui_ImplVulkanH_CreateWindow(g_Instance, g_PhysicalDevice, g_Device, wd, g_QueueFamily, g_Allocator, width, height, g_MinImageCount);
 }
 
 static void CleanupVulkan()
 {
-    ImGui_ImplVulkanH_WindowData* wd = &g_WindowData;
-    ImGui_ImplVulkanH_DestroyWindowData(g_Instance, g_Device, wd, g_Allocator);
     vkDestroyDescriptorPool(g_Device, g_DescriptorPool, g_Allocator);
 
 #ifdef IMGUI_VULKAN_DEBUG_REPORT
@@ -221,7 +231,16 @@ static void CleanupVulkan()
     vkDestroyInstance(g_Instance, g_Allocator);
 }
 
-static void FrameRender(ImGui_ImplVulkanH_WindowData* wd)
+static void CleanupVulkanWindow()
+{
+    // In a normal engine/app integration, you wouldn't use the ImGui_ImplVulkanH_Window helpers,
+    // however you would instead need to call ImGui_ImplVulkan_DestroyFrameRenderBuffers() on each 
+    // ImGui_ImplVulkan_FrameRenderBuffers structure that you own.
+    ImGui_ImplVulkanH_Window* wd = &g_WindowData;
+    ImGui_ImplVulkanH_DestroyWindow(g_Instance, g_Device, wd, g_Allocator);
+}
+
+static void FrameRender(ImGui_ImplVulkanH_Window* wd)
 {
     VkResult err;
 
@@ -229,7 +248,7 @@ static void FrameRender(ImGui_ImplVulkanH_WindowData* wd)
     err = vkAcquireNextImageKHR(g_Device, wd->Swapchain, UINT64_MAX, image_acquired_semaphore, VK_NULL_HANDLE, &wd->FrameIndex);
     check_vk_result(err);
 
-    ImGui_ImplVulkanH_FrameData* fd = &wd->Frames[wd->FrameIndex];
+    ImGui_ImplVulkanH_Frame* fd = &wd->Frames[wd->FrameIndex];
     {
         err = vkWaitForFences(g_Device, 1, &fd->Fence, VK_TRUE, UINT64_MAX);    // wait indefinitely instead of periodically checking
         check_vk_result(err);
@@ -250,7 +269,7 @@ static void FrameRender(ImGui_ImplVulkanH_WindowData* wd)
         VkRenderPassBeginInfo info = {};
         info.sType = VK_STRUCTURE_TYPE_RENDER_PASS_BEGIN_INFO;
         info.renderPass = wd->RenderPass;
-        info.framebuffer = wd->Framebuffer[wd->FrameIndex];
+        info.framebuffer = fd->Framebuffer;
         info.renderArea.extent.width = wd->Width;
         info.renderArea.extent.height = wd->Height;
         info.clearValueCount = 1;
@@ -259,7 +278,7 @@ static void FrameRender(ImGui_ImplVulkanH_WindowData* wd)
     }
 
     // Record Imgui Draw Data and draw funcs into command buffer
-    ImGui_ImplVulkan_RenderDrawData(ImGui::GetDrawData(), fd->CommandBuffer);
+    ImGui_ImplVulkan_RenderDrawData(ImGui::GetDrawData(), fd->CommandBuffer, &fd->RenderBuffers);
 
     // Submit command buffer
     vkCmdEndRenderPass(fd->CommandBuffer);
@@ -282,9 +301,9 @@ static void FrameRender(ImGui_ImplVulkanH_WindowData* wd)
     }
 }
 
-static void FramePresent(ImGui_ImplVulkanH_WindowData* wd)
+static void FramePresent(ImGui_ImplVulkanH_Window* wd)
 {
-    ImGui_ImplVulkanH_FrameData* fd = &wd->Frames[wd->FrameIndex];
+    ImGui_ImplVulkanH_Frame* fd = &wd->Frames[wd->FrameIndex];
     VkPresentInfoKHR info = {};
     info.sType = VK_STRUCTURE_TYPE_PRESENT_INFO_KHR;
     info.waitSemaphoreCount = 1;
@@ -331,8 +350,8 @@ int main(int, char**)
     // Create Framebuffers
     int w, h;
     SDL_GetWindowSize(window, &w, &h);
-    ImGui_ImplVulkanH_WindowData* wd = &g_WindowData;
-    SetupVulkanWindowData(wd, surface, w, h);
+    ImGui_ImplVulkanH_Window* wd = &g_WindowData;
+    SetupVulkanWindow(wd, surface, w, h);
 
     // Setup Dear ImGui context
     ImGui::CreateContext();
@@ -366,6 +385,7 @@ int main(int, char**)
     init_info.PipelineCache = g_PipelineCache;
     init_info.DescriptorPool = g_DescriptorPool;
     init_info.Allocator = g_Allocator;
+    init_info.MinImageCount = g_MinImageCount;
     init_info.CheckVkResultFn = check_vk_result;
     ImGui_ImplVulkan_Init(&init_info, wd->RenderPass);
 
@@ -411,7 +431,7 @@ int main(int, char**)
 
         err = vkDeviceWaitIdle(g_Device);
         check_vk_result(err);
-        ImGui_ImplVulkan_InvalidateFontUploadObjects();
+        ImGui_ImplVulkan_DestroyFontUploadObjects();
     }
 
     bool show_demo_window = true;
@@ -434,7 +454,19 @@ int main(int, char**)
             if (event.type == SDL_QUIT)
                 done = true;
             if (event.type == SDL_WINDOWEVENT && event.window.event == SDL_WINDOWEVENT_RESIZED && event.window.windowID == SDL_GetWindowID(window))
-                ImGui_ImplVulkanH_CreateWindowDataSwapChainAndFramebuffer(g_PhysicalDevice, g_Device, &g_WindowData, g_Allocator, (int)event.window.data1, (int)event.window.data2);
+            {
+                g_SwapChainResizeWidth = (int)event.window.data1;
+                g_SwapChainResizeHeight = (int)event.window.data2;
+                g_SwapChainRebuild = true;
+            }
+        }
+
+        if (g_SwapChainRebuild)
+        {
+            g_SwapChainRebuild = false;
+            ImGui_ImplVulkanH_CreateWindow(g_Instance, g_PhysicalDevice, g_Device, &g_WindowData, g_QueueFamily, g_Allocator, g_SwapChainResizeWidth, g_SwapChainResizeHeight, g_MinImageCount);
+            ImGui_ImplVulkan_SetSwapChainMinImageCount(g_MinImageCount);
+            g_WindowData.FrameIndex = 0;
         }
 
         // Start the Dear ImGui frame
@@ -500,6 +532,8 @@ int main(int, char**)
     ImGui_ImplVulkan_Shutdown();
     ImGui_ImplSDL2_Shutdown();
     ImGui::DestroyContext();
+
+    CleanupVulkanWindow();
     CleanupVulkan();
 
     SDL_DestroyWindow(window);

examples/imgui_impl_vulkan.cpp

@@ -12,8 +12,18 @@
 // The aim of imgui_impl_vulkan.h/.cpp is to be usable in your engine without any modification.
 // IF YOU FEEL YOU NEED TO MAKE ANY CHANGE TO THIS CODE, please share them and your feedback at https://github.com/ocornut/imgui/
 
+// Important note to the reader who wish to integrate imgui_impl_vulkan.cpp/.h in their own engine/app.
+// - Common ImGui_ImplVulkan_XXXX functions and structures are used to interface with imgui_impl_vulkan.cpp/.h.
+//   You will use those if you want to use this rendering back-end in your engine/app.
+// - Helper ImGui_ImplVulkanH_XXXX functions and structures are only used by this example (main.cpp) and by 
+//   the back-end itself (imgui_impl_vulkan.cpp), but should PROBABLY NOT be used by your own engine/app code.
+// Read comments in imgui_impl_vulkan.h.
+
 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
+//  2019-XX-XX: *BREAKING CHANGE*: Vulkan: Added extra parameter to ImGui_ImplVulkan_RenderDrawData(). Engine/app is in charge of owning/storing 1 ImGui_ImplVulkan_FrameRenderBuffers per in-flight rendering frame. (The demo helper ImGui_ImplVulkanH_Window structure carries them.)
+//  2019-XX-XX: *BREAKING CHANGE*: Vulkan: Added MinImageCount field in ImGui_ImplVulkan_InitInfo, required for initialization (was previously a hard #define IMGUI_VK_QUEUED_FRAMES 2). Added ImGui_ImplVulkan_SetSwapChainMinImageCount().
+//  2019-XX-XX: Vulkan: Added VkInstance argument to ImGui_ImplVulkanH_CreateWindow() optional helper.
 //  2019-04-04: Vulkan: Avoid passing negative coordinates to vkCmdSetScissor, which debug validation layers do not like.
 //  2019-04-01: Vulkan: Support for 32-bit index buffer (#define ImDrawIdx unsigned int).
 //  2019-02-16: Vulkan: Viewport and clipping rectangles correctly using draw_data->FramebufferScale to allow retina display.
@@ -36,45 +46,31 @@
 #include <stdio.h>
 
 // Vulkan data
-static const VkAllocationCallbacks* g_Allocator = NULL;
-static VkPhysicalDevice             g_PhysicalDevice = VK_NULL_HANDLE;
-static VkInstance                   g_Instance = VK_NULL_HANDLE;
-static VkDevice                     g_Device = VK_NULL_HANDLE;
-static uint32_t                     g_QueueFamily = (uint32_t)-1;
-static VkQueue                      g_Queue = VK_NULL_HANDLE;
-static VkPipelineCache              g_PipelineCache = VK_NULL_HANDLE;
-static VkDescriptorPool             g_DescriptorPool = VK_NULL_HANDLE;
-static VkRenderPass                 g_RenderPass = VK_NULL_HANDLE;
-static void                         (*g_CheckVkResultFn)(VkResult err) = NULL;
-
-static VkDeviceSize                 g_BufferMemoryAlignment = 256;
-static VkPipelineCreateFlags        g_PipelineCreateFlags = 0;
-
-static VkDescriptorSetLayout        g_DescriptorSetLayout = VK_NULL_HANDLE;
-static VkPipelineLayout             g_PipelineLayout = VK_NULL_HANDLE;
-static VkDescriptorSet              g_DescriptorSet = VK_NULL_HANDLE;
-static VkPipeline                   g_Pipeline = VK_NULL_HANDLE;
-
-// Frame data
-struct FrameDataForRender
-{
-    VkDeviceMemory  VertexBufferMemory;
-    VkDeviceMemory  IndexBufferMemory;
-    VkDeviceSize    VertexBufferSize;
-    VkDeviceSize    IndexBufferSize;
-    VkBuffer        VertexBuffer;
-    VkBuffer        IndexBuffer;
-};
-static int                    g_FrameIndex = 0;
-static FrameDataForRender     g_FramesDataBuffers[IMGUI_VK_QUEUED_FRAMES] = {};
+static ImGui_ImplVulkan_InitInfo g_VulkanInitInfo = {};
+static VkRenderPass             g_RenderPass = VK_NULL_HANDLE;
+static VkDeviceSize             g_BufferMemoryAlignment = 256;
+static VkPipelineCreateFlags    g_PipelineCreateFlags = 0x00;
+static VkDescriptorSetLayout    g_DescriptorSetLayout = VK_NULL_HANDLE;
+static VkPipelineLayout         g_PipelineLayout = VK_NULL_HANDLE;
+static VkDescriptorSet          g_DescriptorSet = VK_NULL_HANDLE;
+static VkPipeline               g_Pipeline = VK_NULL_HANDLE;
 
 // Font data
-static VkSampler              g_FontSampler = VK_NULL_HANDLE;
-static VkDeviceMemory         g_FontMemory = VK_NULL_HANDLE;
-static VkImage                g_FontImage = VK_NULL_HANDLE;
-static VkImageView            g_FontView = VK_NULL_HANDLE;
-static VkDeviceMemory         g_UploadBufferMemory = VK_NULL_HANDLE;
-static VkBuffer               g_UploadBuffer = VK_NULL_HANDLE;
+static VkSampler                g_FontSampler = VK_NULL_HANDLE;
+static VkDeviceMemory           g_FontMemory = VK_NULL_HANDLE;
+static VkImage                  g_FontImage = VK_NULL_HANDLE;
+static VkImageView              g_FontView = VK_NULL_HANDLE;
+static VkDeviceMemory           g_UploadBufferMemory = VK_NULL_HANDLE;
+static VkBuffer                 g_UploadBuffer = VK_NULL_HANDLE;
+
+// Forward Declarations
+void ImGui_ImplVulkanH_DestroyFrame(VkInstance instance, VkDevice device, ImGui_ImplVulkanH_Frame* fd, const VkAllocationCallbacks* allocator);
+void ImGui_ImplVulkanH_CreateWindowSwapChain(VkInstance instance, VkPhysicalDevice physical_device, VkDevice device, ImGui_ImplVulkanH_Window* wd, const VkAllocationCallbacks* allocator, int w, int h, uint32_t min_image_count);
+void ImGui_ImplVulkanH_CreateWindowCommandBuffers(VkInstance instance, VkPhysicalDevice physical_device, VkDevice device, ImGui_ImplVulkanH_Window* wd, uint32_t queue_family, const VkAllocationCallbacks* allocator);
+
+//-----------------------------------------------------------------------------
+// SHADERS
+//-----------------------------------------------------------------------------
 
 // Forward Declarations
 static void ImGui_ImplVulkan_InitPlatformInterface();
@@ -185,10 +181,15 @@ static uint32_t __glsl_shader_frag_spv[] =
     0x00010038
 };
 
+//-----------------------------------------------------------------------------
+// FUNCTIONS
+//-----------------------------------------------------------------------------
+
 static uint32_t ImGui_ImplVulkan_MemoryType(VkMemoryPropertyFlags properties, uint32_t type_bits)
 {
+    ImGui_ImplVulkan_InitInfo* v = &g_VulkanInitInfo;
     VkPhysicalDeviceMemoryProperties prop;
-    vkGetPhysicalDeviceMemoryProperties(g_PhysicalDevice, &prop);
+    vkGetPhysicalDeviceMemoryProperties(v->PhysicalDevice, &prop);
     for (uint32_t i = 0; i < prop.memoryTypeCount; i++)
         if ((prop.memoryTypes[i].propertyFlags & properties) == properties && type_bits & (1<<i))
             return i;
@@ -197,17 +198,19 @@ static uint32_t ImGui_ImplVulkan_MemoryType(VkMemoryPropertyFlags properties, ui
 
 static void check_vk_result(VkResult err)
 {
-    if (g_CheckVkResultFn)
-        g_CheckVkResultFn(err);
+    ImGui_ImplVulkan_InitInfo* v = &g_VulkanInitInfo;
+    if (v->CheckVkResultFn)
+        v->CheckVkResultFn(err);
 }
 
 static void CreateOrResizeBuffer(VkBuffer& buffer, VkDeviceMemory& buffer_memory, VkDeviceSize& p_buffer_size, size_t new_size, VkBufferUsageFlagBits usage)
 {
+    ImGui_ImplVulkan_InitInfo* v = &g_VulkanInitInfo;
     VkResult err;
     if (buffer != VK_NULL_HANDLE)
-        vkDestroyBuffer(g_Device, buffer, g_Allocator);
+        vkDestroyBuffer(v->Device, buffer, v->Allocator);
     if (buffer_memory)
-        vkFreeMemory(g_Device, buffer_memory, g_Allocator);
+        vkFreeMemory(v->Device, buffer_memory, v->Allocator);
 
     VkDeviceSize vertex_buffer_size_aligned = ((new_size - 1) / g_BufferMemoryAlignment + 1) * g_BufferMemoryAlignment;
     VkBufferCreateInfo buffer_info = {};
@@ -215,27 +218,27 @@ static void CreateOrResizeBuffer(VkBuffer& buffer, VkDeviceMemory& buffer_memory
     buffer_info.size = vertex_buffer_size_aligned;
     buffer_info.usage = usage;
     buffer_info.sharingMode = VK_SHARING_MODE_EXCLUSIVE;
-    err = vkCreateBuffer(g_Device, &buffer_info, g_Allocator, &buffer);
+    err = vkCreateBuffer(v->Device, &buffer_info, v->Allocator, &buffer);
     check_vk_result(err);
 
     VkMemoryRequirements req;
-    vkGetBufferMemoryRequirements(g_Device, buffer, &req);
+    vkGetBufferMemoryRequirements(v->Device, buffer, &req);
     g_BufferMemoryAlignment = (g_BufferMemoryAlignment > req.alignment) ? g_BufferMemoryAlignment : req.alignment;
     VkMemoryAllocateInfo alloc_info = {};
     alloc_info.sType = VK_STRUCTURE_TYPE_MEMORY_ALLOCATE_INFO;
     alloc_info.allocationSize = req.size;
     alloc_info.memoryTypeIndex = ImGui_ImplVulkan_MemoryType(VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT, req.memoryTypeBits);
-    err = vkAllocateMemory(g_Device, &alloc_info, g_Allocator, &buffer_memory);
+    err = vkAllocateMemory(v->Device, &alloc_info, v->Allocator, &buffer_memory);
     check_vk_result(err);
 
-    err = vkBindBufferMemory(g_Device, buffer, buffer_memory, 0);
+    err = vkBindBufferMemory(v->Device, buffer, buffer_memory, 0);
     check_vk_result(err);
     p_buffer_size = new_size;
 }
 
 // Render function
 // (this used to be set in io.RenderDrawListsFn and called by ImGui::Render(), but you can now call this directly from your main loop)
-void ImGui_ImplVulkan_RenderDrawData(ImDrawData* draw_data, VkCommandBuffer command_buffer)
+void ImGui_ImplVulkan_RenderDrawData(ImDrawData* draw_data, VkCommandBuffer command_buffer, ImGui_ImplVulkan_FrameRenderBuffers* fd)
 {
     // Avoid rendering when minimized, scale coordinates for retina displays (screen coordinates != framebuffer coordinates)
     int fb_width = (int)(draw_data->DisplaySize.x * draw_data->FramebufferScale.x);
@@ -243,9 +246,8 @@ void ImGui_ImplVulkan_RenderDrawData(ImDrawData* draw_data, VkCommandBuffer comm
     if (fb_width <= 0 || fb_height <= 0 || draw_data->TotalVtxCount == 0)
         return;
 
+    ImGui_ImplVulkan_InitInfo* v = &g_VulkanInitInfo;
     VkResult err;
-    FrameDataForRender* fd = &g_FramesDataBuffers[g_FrameIndex];
-    g_FrameIndex = (g_FrameIndex + 1) % IM_ARRAYSIZE(g_FramesDataBuffers);
 
     // Create the Vertex and Index buffers:
     size_t vertex_size = draw_data->TotalVtxCount * sizeof(ImDrawVert);
@@ -259,9 +261,9 @@ void ImGui_ImplVulkan_RenderDrawData(ImDrawData* draw_data, VkCommandBuffer comm
     {
         ImDrawVert* vtx_dst = NULL;
         ImDrawIdx* idx_dst = NULL;
-        err = vkMapMemory(g_Device, fd->VertexBufferMemory, 0, vertex_size, 0, (void**)(&vtx_dst));
+        err = vkMapMemory(v->Device, fd->VertexBufferMemory, 0, vertex_size, 0, (void**)(&vtx_dst));
         check_vk_result(err);
-        err = vkMapMemory(g_Device, fd->IndexBufferMemory, 0, index_size, 0, (void**)(&idx_dst));
+        err = vkMapMemory(v->Device, fd->IndexBufferMemory, 0, index_size, 0, (void**)(&idx_dst));
         check_vk_result(err);
         for (int n = 0; n < draw_data->CmdListsCount; n++)
         {
@@ -278,10 +280,10 @@ void ImGui_ImplVulkan_RenderDrawData(ImDrawData* draw_data, VkCommandBuffer comm
         range[1].sType = VK_STRUCTURE_TYPE_MAPPED_MEMORY_RANGE;
         range[1].memory = fd->IndexBufferMemory;
         range[1].size = VK_WHOLE_SIZE;
-        err = vkFlushMappedMemoryRanges(g_Device, 2, range);
+        err = vkFlushMappedMemoryRanges(v->Device, 2, range);
         check_vk_result(err);
-        vkUnmapMemory(g_Device, fd->VertexBufferMemory);
-        vkUnmapMemory(g_Device, fd->IndexBufferMemory);
+        vkUnmapMemory(v->Device, fd->VertexBufferMemory);
+        vkUnmapMemory(v->Device, fd->IndexBufferMemory);
     }
 
     // Bind pipeline and descriptor sets:
@@ -379,6 +381,7 @@ void ImGui_ImplVulkan_RenderDrawData(ImDrawData* draw_data, VkCommandBuffer comm
 
 bool ImGui_ImplVulkan_CreateFontsTexture(VkCommandBuffer command_buffer)
 {
+    ImGui_ImplVulkan_InitInfo* v = &g_VulkanInitInfo;
     ImGuiIO& io = ImGui::GetIO();
 
     unsigned char* pixels;
@@ -404,17 +407,17 @@ bool ImGui_ImplVulkan_CreateFontsTexture(VkCommandBuffer command_buffer)
         info.usage = VK_IMAGE_USAGE_SAMPLED_BIT | VK_IMAGE_USAGE_TRANSFER_DST_BIT;
         info.sharingMode = VK_SHARING_MODE_EXCLUSIVE;
         info.initialLayout = VK_IMAGE_LAYOUT_UNDEFINED;
-        err = vkCreateImage(g_Device, &info, g_Allocator, &g_FontImage);
+        err = vkCreateImage(v->Device, &info, v->Allocator, &g_FontImage);
         check_vk_result(err);
         VkMemoryRequirements req;
-        vkGetImageMemoryRequirements(g_Device, g_FontImage, &req);
+        vkGetImageMemoryRequirements(v->Device, g_FontImage, &req);
         VkMemoryAllocateInfo alloc_info = {};
         alloc_info.sType = VK_STRUCTURE_TYPE_MEMORY_ALLOCATE_INFO;
         alloc_info.allocationSize = req.size;
         alloc_info.memoryTypeIndex = ImGui_ImplVulkan_MemoryType(VK_MEMORY_PROPERTY_DEVICE_LOCAL_BIT, req.memoryTypeBits);
-        err = vkAllocateMemory(g_Device, &alloc_info, g_Allocator, &g_FontMemory);
+        err = vkAllocateMemory(v->Device, &alloc_info, v->Allocator, &g_FontMemory);
         check_vk_result(err);
-        err = vkBindImageMemory(g_Device, g_FontImage, g_FontMemory, 0);
+        err = vkBindImageMemory(v->Device, g_FontImage, g_FontMemory, 0);
         check_vk_result(err);
     }
 
@@ -428,7 +431,7 @@ bool ImGui_ImplVulkan_CreateFontsTexture(VkCommandBuffer command_buffer)
         info.subresourceRange.aspectMask = VK_IMAGE_ASPECT_COLOR_BIT;
         info.subresourceRange.levelCount = 1;
         info.subresourceRange.layerCount = 1;
-        err = vkCreateImageView(g_Device, &info, g_Allocator, &g_FontView);
+        err = vkCreateImageView(v->Device, &info, v->Allocator, &g_FontView);
         check_vk_result(err);
     }
 
@@ -444,7 +447,7 @@ bool ImGui_ImplVulkan_CreateFontsTexture(VkCommandBuffer command_buffer)
         write_desc[0].descriptorCount = 1;
         write_desc[0].descriptorType = VK_DESCRIPTOR_TYPE_COMBINED_IMAGE_SAMPLER;
         write_desc[0].pImageInfo = desc_image;
-        vkUpdateDescriptorSets(g_Device, 1, write_desc, 0, NULL);
+        vkUpdateDescriptorSets(v->Device, 1, write_desc, 0, NULL);
     }
 
     // Create the Upload Buffer:
@@ -454,34 +457,34 @@ bool ImGui_ImplVulkan_CreateFontsTexture(VkCommandBuffer command_buffer)
         buffer_info.size = upload_size;
         buffer_info.usage = VK_BUFFER_USAGE_TRANSFER_SRC_BIT;
         buffer_info.sharingMode = VK_SHARING_MODE_EXCLUSIVE;
-        err = vkCreateBuffer(g_Device, &buffer_info, g_Allocator, &g_UploadBuffer);
+        err = vkCreateBuffer(v->Device, &buffer_info, v->Allocator, &g_UploadBuffer);
         check_vk_result(err);
         VkMemoryRequirements req;
-        vkGetBufferMemoryRequirements(g_Device, g_UploadBuffer, &req);
+        vkGetBufferMemoryRequirements(v->Device, g_UploadBuffer, &req);
         g_BufferMemoryAlignment = (g_BufferMemoryAlignment > req.alignment) ? g_BufferMemoryAlignment : req.alignment;
         VkMemoryAllocateInfo alloc_info = {};
         alloc_info.sType = VK_STRUCTURE_TYPE_MEMORY_ALLOCATE_INFO;
         alloc_info.allocationSize = req.size;
         alloc_info.memoryTypeIndex = ImGui_ImplVulkan_MemoryType(VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT, req.memoryTypeBits);
-        err = vkAllocateMemory(g_Device, &alloc_info, g_Allocator, &g_UploadBufferMemory);
+        err = vkAllocateMemory(v->Device, &alloc_info, v->Allocator, &g_UploadBufferMemory);
         check_vk_result(err);
-        err = vkBindBufferMemory(g_Device, g_UploadBuffer, g_UploadBufferMemory, 0);
+        err = vkBindBufferMemory(v->Device, g_UploadBuffer, g_UploadBufferMemory, 0);
         check_vk_result(err);
     }
 
     // Upload to Buffer:
     {
         char* map = NULL;
-        err = vkMapMemory(g_Device, g_UploadBufferMemory, 0, upload_size, 0, (void**)(&map));
+        err = vkMapMemory(v->Device, g_UploadBufferMemory, 0, upload_size, 0, (void**)(&map));
         check_vk_result(err);
         memcpy(map, pixels, upload_size);
         VkMappedMemoryRange range[1] = {};
         range[0].sType = VK_STRUCTURE_TYPE_MAPPED_MEMORY_RANGE;
         range[0].memory = g_UploadBufferMemory;
         range[0].size = upload_size;
-        err = vkFlushMappedMemoryRanges(g_Device, 1, range);
+        err = vkFlushMappedMemoryRanges(v->Device, 1, range);
         check_vk_result(err);
-        vkUnmapMemory(g_Device, g_UploadBufferMemory);
+        vkUnmapMemory(v->Device, g_UploadBufferMemory);
     }
 
     // Copy to Image:
@@ -530,6 +533,7 @@ bool ImGui_ImplVulkan_CreateFontsTexture(VkCommandBuffer command_buffer)
 
 bool ImGui_ImplVulkan_CreateDeviceObjects()
 {
+    ImGui_ImplVulkan_InitInfo* v = &g_VulkanInitInfo;
     VkResult err;
     VkShaderModule vert_module;
     VkShaderModule frag_module;
@@ -540,13 +544,13 @@ bool ImGui_ImplVulkan_CreateDeviceObjects()
         vert_info.sType = VK_STRUCTURE_TYPE_SHADER_MODULE_CREATE_INFO;
         vert_info.codeSize = sizeof(__glsl_shader_vert_spv);
         vert_info.pCode = (uint32_t*)__glsl_shader_vert_spv;
-        err = vkCreateShaderModule(g_Device, &vert_info, g_Allocator, &vert_module);
+        err = vkCreateShaderModule(v->Device, &vert_info, v->Allocator, &vert_module);
         check_vk_result(err);
         VkShaderModuleCreateInfo frag_info = {};
         frag_info.sType = VK_STRUCTURE_TYPE_SHADER_MODULE_CREATE_INFO;
         frag_info.codeSize = sizeof(__glsl_shader_frag_spv);
         frag_info.pCode = (uint32_t*)__glsl_shader_frag_spv;
-        err = vkCreateShaderModule(g_Device, &frag_info, g_Allocator, &frag_module);
+        err = vkCreateShaderModule(v->Device, &frag_info, v->Allocator, &frag_module);
         check_vk_result(err);
     }
 
@@ -563,7 +567,7 @@ bool ImGui_ImplVulkan_CreateDeviceObjects()
         info.minLod = -1000;
         info.maxLod = 1000;
         info.maxAnisotropy = 1.0f;
-        err = vkCreateSampler(g_Device, &info, g_Allocator, &g_FontSampler);
+        err = vkCreateSampler(v->Device, &info, v->Allocator, &g_FontSampler);
         check_vk_result(err);
     }
 
@@ -579,7 +583,7 @@ bool ImGui_ImplVulkan_CreateDeviceObjects()
         info.sType = VK_STRUCTURE_TYPE_DESCRIPTOR_SET_LAYOUT_CREATE_INFO;
         info.bindingCount = 1;
         info.pBindings = binding;
-        err = vkCreateDescriptorSetLayout(g_Device, &info, g_Allocator, &g_DescriptorSetLayout);
+        err = vkCreateDescriptorSetLayout(v->Device, &info, v->Allocator, &g_DescriptorSetLayout);
         check_vk_result(err);
     }
 
@@ -587,10 +591,10 @@ bool ImGui_ImplVulkan_CreateDeviceObjects()
     {
         VkDescriptorSetAllocateInfo alloc_info = {};
         alloc_info.sType = VK_STRUCTURE_TYPE_DESCRIPTOR_SET_ALLOCATE_INFO;
-        alloc_info.descriptorPool = g_DescriptorPool;
+        alloc_info.descriptorPool = v->DescriptorPool;
         alloc_info.descriptorSetCount = 1;
         alloc_info.pSetLayouts = &g_DescriptorSetLayout;
-        err = vkAllocateDescriptorSets(g_Device, &alloc_info, &g_DescriptorSet);
+        err = vkAllocateDescriptorSets(v->Device, &alloc_info, &g_DescriptorSet);
         check_vk_result(err);
     }
 
@@ -608,7 +612,7 @@ bool ImGui_ImplVulkan_CreateDeviceObjects()
         layout_info.pSetLayouts = set_layout;
         layout_info.pushConstantRangeCount = 1;
         layout_info.pPushConstantRanges = push_constants;
-        err = vkCreatePipelineLayout(g_Device, &layout_info, g_Allocator, &g_PipelineLayout);
+        err = vkCreatePipelineLayout(v->Device, &layout_info, v->Allocator, &g_PipelineLayout);
         check_vk_result(err);
     }
 
@@ -706,49 +710,42 @@ bool ImGui_ImplVulkan_CreateDeviceObjects()
     info.pDynamicState = &dynamic_state;
     info.layout = g_PipelineLayout;
     info.renderPass = g_RenderPass;
-    err = vkCreateGraphicsPipelines(g_Device, g_PipelineCache, 1, &info, g_Allocator, &g_Pipeline);
+    err = vkCreateGraphicsPipelines(v->Device, v->PipelineCache, 1, &info, v->Allocator, &g_Pipeline);
     check_vk_result(err);
 
-    vkDestroyShaderModule(g_Device, vert_module, g_Allocator);
-    vkDestroyShaderModule(g_Device, frag_module, g_Allocator);
+    vkDestroyShaderModule(v->Device, vert_module, v->Allocator);
+    vkDestroyShaderModule(v->Device, frag_module, v->Allocator);
 
     return true;
 }
 
-void    ImGui_ImplVulkan_InvalidateFontUploadObjects()
+void    ImGui_ImplVulkan_DestroyFontUploadObjects()
 {
+    ImGui_ImplVulkan_InitInfo* v = &g_VulkanInitInfo;
     if (g_UploadBuffer)
     {
-        vkDestroyBuffer(g_Device, g_UploadBuffer, g_Allocator);
+        vkDestroyBuffer(v->Device, g_UploadBuffer, v->Allocator);
         g_UploadBuffer = VK_NULL_HANDLE;
     }
     if (g_UploadBufferMemory)
     {
-        vkFreeMemory(g_Device, g_UploadBufferMemory, g_Allocator);
+        vkFreeMemory(v->Device, g_UploadBufferMemory, v->Allocator);
         g_UploadBufferMemory = VK_NULL_HANDLE;
     }
 }
 
-void    ImGui_ImplVulkan_InvalidateDeviceObjects()
+void    ImGui_ImplVulkan_DestroyDeviceObjects()
 {
-    ImGui_ImplVulkan_InvalidateFontUploadObjects();
-
-    for (int i = 0; i < IM_ARRAYSIZE(g_FramesDataBuffers); i++)
-    {
-        FrameDataForRender* fd = &g_FramesDataBuffers[i];
-        if (fd->VertexBuffer)       { vkDestroyBuffer   (g_Device, fd->VertexBuffer,        g_Allocator); fd->VertexBuffer = VK_NULL_HANDLE; }
-        if (fd->VertexBufferMemory) { vkFreeMemory      (g_Device, fd->VertexBufferMemory,  g_Allocator); fd->VertexBufferMemory = VK_NULL_HANDLE; }
-        if (fd->IndexBuffer)        { vkDestroyBuffer   (g_Device, fd->IndexBuffer,         g_Allocator); fd->IndexBuffer = VK_NULL_HANDLE; }
-        if (fd->IndexBufferMemory)  { vkFreeMemory      (g_Device, fd->IndexBufferMemory,   g_Allocator); fd->IndexBufferMemory = VK_NULL_HANDLE; }
-    }
-
-    if (g_FontView)             { vkDestroyImageView(g_Device, g_FontView, g_Allocator); g_FontView = VK_NULL_HANDLE; }
-    if (g_FontImage)            { vkDestroyImage(g_Device, g_FontImage, g_Allocator); g_FontImage = VK_NULL_HANDLE; }
-    if (g_FontMemory)           { vkFreeMemory(g_Device, g_FontMemory, g_Allocator); g_FontMemory = VK_NULL_HANDLE; }
-    if (g_FontSampler)          { vkDestroySampler(g_Device, g_FontSampler, g_Allocator); g_FontSampler = VK_NULL_HANDLE; }
-    if (g_DescriptorSetLayout)  { vkDestroyDescriptorSetLayout(g_Device, g_DescriptorSetLayout, g_Allocator); g_DescriptorSetLayout = VK_NULL_HANDLE; }
-    if (g_PipelineLayout)       { vkDestroyPipelineLayout(g_Device, g_PipelineLayout, g_Allocator); g_PipelineLayout = VK_NULL_HANDLE; }
-    if (g_Pipeline)             { vkDestroyPipeline(g_Device, g_Pipeline, g_Allocator); g_Pipeline = VK_NULL_HANDLE; }
+    ImGui_ImplVulkan_InitInfo* v = &g_VulkanInitInfo;
+
+    ImGui_ImplVulkan_DestroyFontUploadObjects();
+    if (g_FontView)             { vkDestroyImageView(v->Device, g_FontView, v->Allocator); g_FontView = VK_NULL_HANDLE; }
+    if (g_FontImage)            { vkDestroyImage(v->Device, g_FontImage, v->Allocator); g_FontImage = VK_NULL_HANDLE; }
+    if (g_FontMemory)           { vkFreeMemory(v->Device, g_FontMemory, v->Allocator); g_FontMemory = VK_NULL_HANDLE; }
+    if (g_FontSampler)          { vkDestroySampler(v->Device, g_FontSampler, v->Allocator); g_FontSampler = VK_NULL_HANDLE; }
+    if (g_DescriptorSetLayout)  { vkDestroyDescriptorSetLayout(v->Device, g_DescriptorSetLayout, v->Allocator); g_DescriptorSetLayout = VK_NULL_HANDLE; }
+    if (g_PipelineLayout)       { vkDestroyPipelineLayout(v->Device, g_PipelineLayout, v->Allocator); g_PipelineLayout = VK_NULL_HANDLE; }
+    if (g_Pipeline)             { vkDestroyPipeline(v->Device, g_Pipeline, v->Allocator); g_Pipeline = VK_NULL_HANDLE; }
 }
 
 bool    ImGui_ImplVulkan_Init(ImGui_ImplVulkan_InitInfo* info, VkRenderPass render_pass)
@@ -763,19 +760,11 @@ bool    ImGui_ImplVulkan_Init(ImGui_ImplVulkan_InitInfo* info, VkRenderPass rend
     IM_ASSERT(info->Device != VK_NULL_HANDLE);
     IM_ASSERT(info->Queue != VK_NULL_HANDLE);
     IM_ASSERT(info->DescriptorPool != VK_NULL_HANDLE);
+    IM_ASSERT(info->MinImageCount >= 2);
     IM_ASSERT(render_pass != VK_NULL_HANDLE);
 
-    g_Instance = info->Instance;
-    g_PhysicalDevice = info->PhysicalDevice;
-    g_Device = info->Device;
-    g_QueueFamily = info->QueueFamily;
-    g_Queue = info->Queue;
+    g_VulkanInitInfo = *info;
     g_RenderPass = render_pass;
-    g_PipelineCache = info->PipelineCache;
-    g_DescriptorPool = info->DescriptorPool;
-    g_Allocator = info->Allocator;
-    g_CheckVkResultFn = info->CheckVkResultFn;
-
     ImGui_ImplVulkan_CreateDeviceObjects();
 
     if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
@@ -787,16 +776,37 @@ bool    ImGui_ImplVulkan_Init(ImGui_ImplVulkan_InitInfo* info, VkRenderPass rend
 void ImGui_ImplVulkan_Shutdown()
 {
     ImGui_ImplVulkan_ShutdownPlatformInterface();
-    ImGui_ImplVulkan_InvalidateDeviceObjects();
+    ImGui_ImplVulkan_DestroyDeviceObjects();
 }
 
 void ImGui_ImplVulkan_NewFrame()
 {
 }
 
+// Note: this has no effect in the 'master' branch, but multi-viewports needs this to recreate swap-chains.
+void ImGui_ImplVulkan_SetSwapChainMinImageCount(int min_image_count)
+{
+    IM_ASSERT(min_image_count >= 2);
+    g_VulkanInitInfo.MinImageCount = min_image_count;
+}
+
+// This is a public function because we require the user to pass a ImGui_ImplVulkan_FrameRenderBuffers 
+// structure to ImGui_ImplVulkan_RenderDrawData.
+void ImGui_ImplVulkan_DestroyFrameRenderBuffers(VkInstance instance, VkDevice device, ImGui_ImplVulkan_FrameRenderBuffers* buffers, const VkAllocationCallbacks* allocator)
+{
+    (void)instance;
+    if (buffers->VertexBuffer)       { vkDestroyBuffer(device, buffers->VertexBuffer,       allocator); buffers->VertexBuffer = VK_NULL_HANDLE; }
+    if (buffers->VertexBufferMemory) { vkFreeMemory   (device, buffers->VertexBufferMemory, allocator); buffers->VertexBufferMemory = VK_NULL_HANDLE; }
+    if (buffers->IndexBuffer)        { vkDestroyBuffer(device, buffers->IndexBuffer,        allocator); buffers->IndexBuffer = VK_NULL_HANDLE; }
+    if (buffers->IndexBufferMemory)  { vkFreeMemory   (device, buffers->IndexBufferMemory,  allocator); buffers->IndexBufferMemory = VK_NULL_HANDLE; }
+    buffers->VertexBufferSize = 0;
+    buffers->IndexBufferSize = 0;
+}
+
 
 //-------------------------------------------------------------------------
 // Internal / Miscellaneous Vulkan Helpers
+// (Used by example's main.cpp. Used by multi-viewport features. PROBABLY NOT used by your own app.)
 //-------------------------------------------------------------------------
 // You probably do NOT need to use or care about those functions.
 // Those functions only exist because:
@@ -804,40 +814,14 @@ void ImGui_ImplVulkan_NewFrame()
 //   2) the upcoming multi-viewport feature will need them internally.
 // Generally we avoid exposing any kind of superfluous high-level helpers in the bindings,
 // but it is too much code to duplicate everywhere so we exceptionally expose them.
-// Your application/engine will likely already have code to setup all that stuff (swap chain, render pass, frame buffers, etc.).
+//
+// Your engine/app will likely _already_ have code to setup all that stuff (swap chain, render pass, frame buffers, etc.).
 // You may read this code to learn about Vulkan, but it is recommended you use you own custom tailored code to do equivalent work.
-// (those functions do not interact with any of the state used by the regular ImGui_ImplVulkan_XXX functions)
+// (The ImGui_ImplVulkanH_XXX functions do not interact with any of the state used by the regular ImGui_ImplVulkan_XXX functions)
 //-------------------------------------------------------------------------
 
 #include <stdlib.h> // malloc
 
-ImGui_ImplVulkanH_FrameData::ImGui_ImplVulkanH_FrameData()
-{
-    BackbufferIndex = 0;
-    CommandPool = VK_NULL_HANDLE;
-    CommandBuffer = VK_NULL_HANDLE;
-    Fence = VK_NULL_HANDLE;
-    ImageAcquiredSemaphore = VK_NULL_HANDLE;
-    RenderCompleteSemaphore = VK_NULL_HANDLE;
-}
-
-ImGui_ImplVulkanH_WindowData::ImGui_ImplVulkanH_WindowData()
-{
-    Width = Height = 0;
-    Swapchain = VK_NULL_HANDLE;
-    Surface = VK_NULL_HANDLE;
-    memset(&SurfaceFormat, 0, sizeof(SurfaceFormat));
-    PresentMode = VK_PRESENT_MODE_MAX_ENUM_KHR;
-    RenderPass = VK_NULL_HANDLE;
-    ClearEnable = true;
-    memset(&ClearValue, 0, sizeof(ClearValue));
-    BackBufferCount = 0;
-    memset(&BackBuffer, 0, sizeof(BackBuffer));
-    memset(&BackBufferView, 0, sizeof(BackBufferView));
-    memset(&Framebuffer, 0, sizeof(Framebuffer));
-    FrameIndex = 0;
-}
-
 VkSurfaceFormatKHR ImGui_ImplVulkanH_SelectSurfaceFormat(VkPhysicalDevice physical_device, VkSurfaceKHR surface, const VkFormat* request_formats, int request_formats_count, VkColorSpaceKHR request_color_space)
 {
     IM_ASSERT(request_formats != NULL);
@@ -904,17 +888,18 @@ VkPresentModeKHR ImGui_ImplVulkanH_SelectPresentMode(VkPhysicalDevice physical_d
     return VK_PRESENT_MODE_FIFO_KHR; // Always available
 }
 
-void ImGui_ImplVulkanH_CreateWindowDataCommandBuffers(VkPhysicalDevice physical_device, VkDevice device, uint32_t queue_family, ImGui_ImplVulkanH_WindowData* wd, const VkAllocationCallbacks* allocator)
+void ImGui_ImplVulkanH_CreateWindowCommandBuffers(VkInstance instance, VkPhysicalDevice physical_device, VkDevice device, ImGui_ImplVulkanH_Window* wd, uint32_t queue_family, const VkAllocationCallbacks* allocator)
 {
-    IM_ASSERT(physical_device != VK_NULL_HANDLE && device != VK_NULL_HANDLE);
+    IM_ASSERT(instance != VK_NULL_HANDLE && physical_device != VK_NULL_HANDLE && device != VK_NULL_HANDLE);
+    (void)instance;
     (void)physical_device;
     (void)allocator;
 
     // Create Command Buffers
     VkResult err;
-    for (int i = 0; i < IM_ARRAYSIZE(wd->Frames); i++)
+    for (uint32_t i = 0; i < wd->FramesQueueSize; i++)
     {
-        ImGui_ImplVulkanH_FrameData* fd = &wd->Frames[i];
+        ImGui_ImplVulkanH_Frame* fd = &wd->Frames[i];
         {
             VkCommandPoolCreateInfo info = {};
             info.sType = VK_STRUCTURE_TYPE_COMMAND_POOL_CREATE_INFO;
@@ -962,24 +947,21 @@ int ImGui_ImplVulkanH_GetMinImageCountFromPresentMode(VkPresentModeKHR present_m
     return 1;
 }
 
-void ImGui_ImplVulkanH_CreateWindowDataSwapChainAndFramebuffer(VkPhysicalDevice physical_device, VkDevice device, ImGui_ImplVulkanH_WindowData* wd, const VkAllocationCallbacks* allocator, int w, int h)
+// Also destroy old swap chain and in-flight frames data, if any.
+void ImGui_ImplVulkanH_CreateWindowSwapChain(VkInstance instance, VkPhysicalDevice physical_device, VkDevice device, ImGui_ImplVulkanH_Window* wd, const VkAllocationCallbacks* allocator, int w, int h, uint32_t min_image_count)
 {
-    uint32_t min_image_count = 2;   // FIXME: this should become a function parameter
-
     VkResult err;
     VkSwapchainKHR old_swapchain = wd->Swapchain;
     err = vkDeviceWaitIdle(device);
     check_vk_result(err);
 
+    // We don't use ImGui_ImplVulkanH_DestroyWindow() because we want to preserve the old swapchain to create the new one.
     // Destroy old Framebuffer
-    for (uint32_t i = 0; i < wd->BackBufferCount; i++)
-    {
-        if (wd->BackBufferView[i])
-            vkDestroyImageView(device, wd->BackBufferView[i], allocator);
-        if (wd->Framebuffer[i])
-            vkDestroyFramebuffer(device, wd->Framebuffer[i], allocator);
-    }
-    wd->BackBufferCount = 0;
+    for (uint32_t i = 0; i < wd->FramesQueueSize; i++)
+        ImGui_ImplVulkanH_DestroyFrame(instance, device, &wd->Frames[i], allocator);
+    delete[] wd->Frames;
+    wd->Frames = NULL;
+    wd->FramesQueueSize = 0;
     if (wd->RenderPass)
         vkDestroyRenderPass(device, wd->RenderPass, allocator);
 
@@ -1023,10 +1005,19 @@ void ImGui_ImplVulkanH_CreateWindowDataSwapChainAndFramebuffer(VkPhysicalDevice
         }
         err = vkCreateSwapchainKHR(device, &info, allocator, &wd->Swapchain);
         check_vk_result(err);
-        err = vkGetSwapchainImagesKHR(device, wd->Swapchain, &wd->BackBufferCount, NULL);
+        err = vkGetSwapchainImagesKHR(device, wd->Swapchain, &wd->FramesQueueSize, NULL);
         check_vk_result(err);
-        err = vkGetSwapchainImagesKHR(device, wd->Swapchain, &wd->BackBufferCount, wd->BackBuffer);
+        VkImage backbuffers[16] = {};
+        IM_ASSERT(wd->FramesQueueSize >= min_image_count);
+        IM_ASSERT(wd->FramesQueueSize < IM_ARRAYSIZE(backbuffers));
+        err = vkGetSwapchainImagesKHR(device, wd->Swapchain, &wd->FramesQueueSize, backbuffers);
         check_vk_result(err);
+
+        IM_ASSERT(wd->Frames == NULL);
+        wd->Frames = new ImGui_ImplVulkanH_Frame[wd->FramesQueueSize];
+        memset(wd->Frames, 0, sizeof(wd->Frames[0]) * wd->FramesQueueSize);
+        for (uint32_t i = 0; i < wd->FramesQueueSize; i++)
+            wd->Frames[i].Backbuffer = backbuffers[i];
     }
     if (old_swapchain)
         vkDestroySwapchainKHR(device, old_swapchain, allocator);
@@ -1080,10 +1071,11 @@ void ImGui_ImplVulkanH_CreateWindowDataSwapChainAndFramebuffer(VkPhysicalDevice
         info.components.a = VK_COMPONENT_SWIZZLE_A;
         VkImageSubresourceRange image_range = { VK_IMAGE_ASPECT_COLOR_BIT, 0, 1, 0, 1 };
         info.subresourceRange = image_range;
-        for (uint32_t i = 0; i < wd->BackBufferCount; i++)
+        for (uint32_t i = 0; i < wd->FramesQueueSize; i++)
         {
-            info.image = wd->BackBuffer[i];
-            err = vkCreateImageView(device, &info, allocator, &wd->BackBufferView[i]);
+            ImGui_ImplVulkanH_Frame* fd = &wd->Frames[i];
+            info.image = fd->Backbuffer;
+            err = vkCreateImageView(device, &info, allocator, &fd->BackbufferView);
             check_vk_result(err);
         }
     }
@@ -1099,40 +1091,58 @@ void ImGui_ImplVulkanH_CreateWindowDataSwapChainAndFramebuffer(VkPhysicalDevice
         info.width = wd->Width;
         info.height = wd->Height;
         info.layers = 1;
-        for (uint32_t i = 0; i < wd->BackBufferCount; i++)
+        for (uint32_t i = 0; i < wd->FramesQueueSize; i++)
         {
-            attachment[0] = wd->BackBufferView[i];
-            err = vkCreateFramebuffer(device, &info, allocator, &wd->Framebuffer[i]);
+            ImGui_ImplVulkanH_Frame* fd = &wd->Frames[i];
+            attachment[0] = fd->BackbufferView;
+            err = vkCreateFramebuffer(device, &info, allocator, &fd->Framebuffer);
             check_vk_result(err);
         }
     }
 }
 
-void ImGui_ImplVulkanH_DestroyWindowData(VkInstance instance, VkDevice device, ImGui_ImplVulkanH_WindowData* wd, const VkAllocationCallbacks* allocator)
+void ImGui_ImplVulkanH_CreateWindow(VkInstance instance, VkPhysicalDevice physical_device, VkDevice device, ImGui_ImplVulkanH_Window* wd, uint32_t queue_family, const VkAllocationCallbacks* allocator, int width, int height, uint32_t min_image_count)
+{
+    ImGui_ImplVulkanH_CreateWindowSwapChain(instance, physical_device, device, wd, allocator, width, height, min_image_count);
+    ImGui_ImplVulkanH_CreateWindowCommandBuffers(instance, physical_device, device, wd, queue_family, allocator);
+}
+
+void ImGui_ImplVulkanH_DestroyWindow(VkInstance instance, VkDevice device, ImGui_ImplVulkanH_Window* wd, const VkAllocationCallbacks* allocator)
 {
     vkDeviceWaitIdle(device); // FIXME: We could wait on the Queue if we had the queue in wd-> (otherwise VulkanH functions can't use globals)
     //vkQueueWaitIdle(g_Queue);
 
-    for (int i = 0; i < IM_ARRAYSIZE(wd->Frames); i++)
-    {
-        ImGui_ImplVulkanH_FrameData* fd = &wd->Frames[i];
-        vkDestroyFence(device, fd->Fence, allocator);
-        vkFreeCommandBuffers(device, fd->CommandPool, 1, &fd->CommandBuffer);
-        vkDestroyCommandPool(device, fd->CommandPool, allocator);
-        vkDestroySemaphore(device, fd->ImageAcquiredSemaphore, allocator);
-        vkDestroySemaphore(device, fd->RenderCompleteSemaphore, allocator);
-    }
-    for (uint32_t i = 0; i < wd->BackBufferCount; i++)
-    {
-        vkDestroyImageView(device, wd->BackBufferView[i], allocator);
-        vkDestroyFramebuffer(device, wd->Framebuffer[i], allocator);
-    }
+    for (uint32_t i = 0; i < wd->FramesQueueSize; i++)
+        ImGui_ImplVulkanH_DestroyFrame(instance, device, &wd->Frames[i], allocator);
+    delete[] wd->Frames;
+    wd->Frames = NULL;
     vkDestroyRenderPass(device, wd->RenderPass, allocator);
     vkDestroySwapchainKHR(device, wd->Swapchain, allocator);
     vkDestroySurfaceKHR(instance, wd->Surface, allocator);
-    *wd = ImGui_ImplVulkanH_WindowData();
+
+    *wd = ImGui_ImplVulkanH_Window();
 }
 
+void ImGui_ImplVulkanH_DestroyFrame(VkInstance instance, VkDevice device, ImGui_ImplVulkanH_Frame* fd, const VkAllocationCallbacks* allocator)
+{
+    (void)instance;
+    vkDestroyFence(device, fd->Fence, allocator);
+    vkFreeCommandBuffers(device, fd->CommandPool, 1, &fd->CommandBuffer);
+    vkDestroyCommandPool(device, fd->CommandPool, allocator);
+    vkDestroySemaphore(device, fd->ImageAcquiredSemaphore, allocator);
+    vkDestroySemaphore(device, fd->RenderCompleteSemaphore, allocator);
+    fd->Fence = VK_NULL_HANDLE;
+    fd->CommandBuffer = VK_NULL_HANDLE;
+    fd->CommandPool = VK_NULL_HANDLE;
+    fd->ImageAcquiredSemaphore = fd->RenderCompleteSemaphore = VK_NULL_HANDLE;
+
+    vkDestroyImageView(device, fd->BackbufferView, allocator);
+    vkDestroyFramebuffer(device, fd->Framebuffer, allocator);
+
+    ImGui_ImplVulkan_DestroyFrameRenderBuffers(instance, device, &fd->RenderBuffers, allocator);
+}
+
+
 //--------------------------------------------------------------------------------------------------------
 // MULTI-VIEWPORT / PLATFORM INTERFACE SUPPORT
 // This is an _advanced_ and _optional_ feature, allowing the back-end to create and handle multiple viewports simultaneously.
@@ -1143,7 +1153,7 @@ void ImGui_ImplVulkanH_DestroyWindowData(VkInstance instance, VkDevice device, I
 
 struct ImGuiViewportDataVulkan
 {
-    ImGui_ImplVulkanH_WindowData WindowData;
+    ImGui_ImplVulkanH_Window Window;
 
     ImGuiViewportDataVulkan() { }
     ~ImGuiViewportDataVulkan() { }
@@ -1153,16 +1163,17 @@ static void ImGui_ImplVulkan_CreateWindow(ImGuiViewport* viewport)
 {
     ImGuiViewportDataVulkan* data = IM_NEW(ImGuiViewportDataVulkan)();
     viewport->RendererUserData = data;
-    ImGui_ImplVulkanH_WindowData* wd = &data->WindowData;
+    ImGui_ImplVulkanH_Window* wd = &data->Window;
+    ImGui_ImplVulkan_InitInfo* v = &g_VulkanInitInfo;
 
     // Create surface
     ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
-    VkResult err = (VkResult)platform_io.Platform_CreateVkSurface(viewport, (ImU64)g_Instance, (const void*)g_Allocator, (ImU64*)&wd->Surface);
+    VkResult err = (VkResult)platform_io.Platform_CreateVkSurface(viewport, (ImU64)v->Instance, (const void*)v->Allocator, (ImU64*)&wd->Surface);
     check_vk_result(err);
 
     // Check for WSI support
     VkBool32 res;
-    vkGetPhysicalDeviceSurfaceSupportKHR(g_PhysicalDevice, g_QueueFamily, wd->Surface, &res);
+    vkGetPhysicalDeviceSurfaceSupportKHR(v->PhysicalDevice, v->QueueFamily, wd->Surface, &res);
     if (res != VK_TRUE)
     {
         fprintf(stderr, "Error no WSI support on physical device 0\n");
@@ -1172,18 +1183,17 @@ static void ImGui_ImplVulkan_CreateWindow(ImGuiViewport* viewport)
     // Select Surface Format
     const VkFormat requestSurfaceImageFormat[] = { VK_FORMAT_B8G8R8A8_UNORM, VK_FORMAT_R8G8B8A8_UNORM, VK_FORMAT_B8G8R8_UNORM, VK_FORMAT_R8G8B8_UNORM };
     const VkColorSpaceKHR requestSurfaceColorSpace = VK_COLORSPACE_SRGB_NONLINEAR_KHR;
-    wd->SurfaceFormat = ImGui_ImplVulkanH_SelectSurfaceFormat(g_PhysicalDevice, wd->Surface, requestSurfaceImageFormat, (size_t)IM_ARRAYSIZE(requestSurfaceImageFormat), requestSurfaceColorSpace);
+    wd->SurfaceFormat = ImGui_ImplVulkanH_SelectSurfaceFormat(v->PhysicalDevice, wd->Surface, requestSurfaceImageFormat, (size_t)IM_ARRAYSIZE(requestSurfaceImageFormat), requestSurfaceColorSpace);
 
     // Select Present Mode
     // FIXME-VULKAN: Even thought mailbox seems to get us maximum framerate with a single window, it halves framerate with a second window etc. (w/ Nvidia and SDK 1.82.1)
     VkPresentModeKHR present_modes[] = { VK_PRESENT_MODE_MAILBOX_KHR, VK_PRESENT_MODE_IMMEDIATE_KHR, VK_PRESENT_MODE_FIFO_KHR };
-    wd->PresentMode = ImGui_ImplVulkanH_SelectPresentMode(g_PhysicalDevice, wd->Surface, &present_modes[0], IM_ARRAYSIZE(present_modes));
+    wd->PresentMode = ImGui_ImplVulkanH_SelectPresentMode(v->PhysicalDevice, wd->Surface, &present_modes[0], IM_ARRAYSIZE(present_modes));
     //printf("[vulkan] Secondary window selected PresentMode = %d\n", wd->PresentMode);
 
     // Create SwapChain, RenderPass, Framebuffer, etc.
     wd->ClearEnable = (viewport->Flags & ImGuiViewportFlags_NoRendererClear) ? false : true;
-    ImGui_ImplVulkanH_CreateWindowDataCommandBuffers(g_PhysicalDevice, g_Device, g_QueueFamily, wd, g_Allocator);
-    ImGui_ImplVulkanH_CreateWindowDataSwapChainAndFramebuffer(g_PhysicalDevice, g_Device, wd, g_Allocator, (int)viewport->Size.x, (int)viewport->Size.y);
+    ImGui_ImplVulkanH_CreateWindow(v->Instance, v->PhysicalDevice, v->Device, wd, v->QueueFamily, v->Allocator, (int)viewport->Size.x, (int)viewport->Size.y, v->MinImageCount);
 }
 
 static void ImGui_ImplVulkan_DestroyWindow(ImGuiViewport* viewport)
@@ -1191,7 +1201,8 @@ static void ImGui_ImplVulkan_DestroyWindow(ImGuiViewport* viewport)
     // The main viewport (owned by the application) will always have RendererUserData == NULL since we didn't create the data for it.
     if (ImGuiViewportDataVulkan* data = (ImGuiViewportDataVulkan*)viewport->RendererUserData)
     {
-        ImGui_ImplVulkanH_DestroyWindowData(g_Instance, g_Device, &data->WindowData, g_Allocator);
+        ImGui_ImplVulkan_InitInfo* v = &g_VulkanInitInfo;
+        ImGui_ImplVulkanH_DestroyWindow(v->Instance, v->Device, &data->Window, v->Allocator);
         IM_DELETE(data);
     }
     viewport->RendererUserData = NULL;
@@ -1202,31 +1213,34 @@ static void ImGui_ImplVulkan_SetWindowSize(ImGuiViewport* viewport, ImVec2 size)
     ImGuiViewportDataVulkan* data = (ImGuiViewportDataVulkan*)viewport->RendererUserData;
     if (data == NULL) // This is NULL for the main viewport (which is left to the user/app to handle)
         return;
-    data->WindowData.ClearEnable = (viewport->Flags & ImGuiViewportFlags_NoRendererClear) ? false : true;
-    ImGui_ImplVulkanH_CreateWindowDataSwapChainAndFramebuffer(g_PhysicalDevice, g_Device, &data->WindowData, g_Allocator, (int)size.x, (int)size.y);
+    ImGui_ImplVulkan_InitInfo* v = &g_VulkanInitInfo;
+    data->Window.ClearEnable = (viewport->Flags & ImGuiViewportFlags_NoRendererClear) ? false : true;
+    ImGui_ImplVulkanH_CreateWindowSwapChain(v->Instance, v->PhysicalDevice, v->Device, &data->Window, v->Allocator, (int)size.x, (int)size.y, v->MinImageCount);
 }
 
 static void ImGui_ImplVulkan_RenderWindow(ImGuiViewport* viewport, void*)
 {
     ImGuiViewportDataVulkan* data = (ImGuiViewportDataVulkan*)viewport->RendererUserData;
-    ImGui_ImplVulkanH_WindowData* wd = &data->WindowData;
+    ImGui_ImplVulkanH_Window* wd = &data->Window;
+    ImGui_ImplVulkan_InitInfo* v = &g_VulkanInitInfo;
     VkResult err;
 
     {
-        ImGui_ImplVulkanH_FrameData* fd = &wd->Frames[wd->FrameIndex];
+        ImGui_ImplVulkanH_Frame* fd = &wd->Frames[wd->FrameIndex];
         for (;;)
         {
-            err = vkWaitForFences(g_Device, 1, &fd->Fence, VK_TRUE, 100);
+            err = vkWaitForFences(v->Device, 1, &fd->Fence, VK_TRUE, 100);
             if (err == VK_SUCCESS) break;
             if (err == VK_TIMEOUT) continue;
             check_vk_result(err);
         }
         {
-            err = vkAcquireNextImageKHR(g_Device, wd->Swapchain, UINT64_MAX, fd->ImageAcquiredSemaphore, VK_NULL_HANDLE, &fd->BackbufferIndex);
+            err = vkAcquireNextImageKHR(v->Device, wd->Swapchain, UINT64_MAX, fd->ImageAcquiredSemaphore, VK_NULL_HANDLE, &fd->BackbufferCurrentIndex);
             check_vk_result(err);
         }
+        IM_ASSERT(wd->FrameIndex == fd->BackbufferCurrentIndex); // FIXME
         {
-            err = vkResetCommandPool(g_Device, fd->CommandPool, 0);
+            err = vkResetCommandPool(v->Device, fd->CommandPool, 0);
             check_vk_result(err);
             VkCommandBufferBeginInfo info = {};
             info.sType = VK_STRUCTURE_TYPE_COMMAND_BUFFER_BEGIN_INFO;
@@ -1241,7 +1255,7 @@ static void ImGui_ImplVulkan_RenderWindow(ImGuiViewport* viewport, void*)
             VkRenderPassBeginInfo info = {};
             info.sType = VK_STRUCTURE_TYPE_RENDER_PASS_BEGIN_INFO;
             info.renderPass = wd->RenderPass;
-            info.framebuffer = wd->Framebuffer[fd->BackbufferIndex];
+            info.framebuffer = wd->Frames[fd->BackbufferCurrentIndex].Framebuffer;
             info.renderArea.extent.width = wd->Width;
             info.renderArea.extent.height = wd->Height;
             info.clearValueCount = (viewport->Flags & ImGuiViewportFlags_NoRendererClear) ? 0 : 1;
@@ -1250,10 +1264,10 @@ static void ImGui_ImplVulkan_RenderWindow(ImGuiViewport* viewport, void*)
         }
     }
 
-    ImGui_ImplVulkan_RenderDrawData(viewport->DrawData, wd->Frames[wd->FrameIndex].CommandBuffer);
+    ImGui_ImplVulkanH_Frame* fd = &wd->Frames[wd->FrameIndex];
+    ImGui_ImplVulkan_RenderDrawData(viewport->DrawData, fd->CommandBuffer, &fd->RenderBuffers);
 
     {
-        ImGui_ImplVulkanH_FrameData* fd = &wd->Frames[wd->FrameIndex];
         vkCmdEndRenderPass(fd->CommandBuffer);
         {
             VkPipelineStageFlags wait_stage = VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT;
@@ -1269,9 +1283,9 @@ static void ImGui_ImplVulkan_RenderWindow(ImGuiViewport* viewport, void*)
 
             err = vkEndCommandBuffer(fd->CommandBuffer);
             check_vk_result(err);
-            err = vkResetFences(g_Device, 1, &fd->Fence);
+            err = vkResetFences(v->Device, 1, &fd->Fence);
             check_vk_result(err);
-            err = vkQueueSubmit(g_Queue, 1, &info, fd->Fence);
+            err = vkQueueSubmit(v->Queue, 1, &info, fd->Fence);
             check_vk_result(err);
         }
     }
@@ -1280,22 +1294,23 @@ static void ImGui_ImplVulkan_RenderWindow(ImGuiViewport* viewport, void*)
 static void ImGui_ImplVulkan_SwapBuffers(ImGuiViewport* viewport, void*)
 {
     ImGuiViewportDataVulkan* data = (ImGuiViewportDataVulkan*)viewport->RendererUserData;
-    ImGui_ImplVulkanH_WindowData* wd = &data->WindowData;
+    ImGui_ImplVulkanH_Window* wd = &data->Window;
+    ImGui_ImplVulkan_InitInfo* v = &g_VulkanInitInfo;
 
     VkResult err;
     uint32_t PresentIndex = wd->FrameIndex;
 
-    ImGui_ImplVulkanH_FrameData* fd = &wd->Frames[PresentIndex];
+    ImGui_ImplVulkanH_Frame* fd = &wd->Frames[PresentIndex];
     VkPresentInfoKHR info = {};
     info.sType = VK_STRUCTURE_TYPE_PRESENT_INFO_KHR;
     info.waitSemaphoreCount = 1;
     info.pWaitSemaphores = &fd->RenderCompleteSemaphore;
     info.swapchainCount = 1;
     info.pSwapchains = &wd->Swapchain;
-    info.pImageIndices = &fd->BackbufferIndex;
-    err = vkQueuePresentKHR(g_Queue, &info);
+    info.pImageIndices = &fd->BackbufferCurrentIndex;
+    err = vkQueuePresentKHR(v->Queue, &info);
     check_vk_result(err);
-    wd->FrameIndex = (wd->FrameIndex + 1) % IMGUI_VK_QUEUED_FRAMES;
+    wd->FrameIndex = (wd->FrameIndex + 1) % wd->FramesQueueSize;
 }
 
 void ImGui_ImplVulkan_InitPlatformInterface()

examples/imgui_impl_vulkan.h

@@ -12,42 +12,65 @@
 // The aim of imgui_impl_vulkan.h/.cpp is to be usable in your engine without any modification.
 // IF YOU FEEL YOU NEED TO MAKE ANY CHANGE TO THIS CODE, please share them and your feedback at https://github.com/ocornut/imgui/
 
+// Important note to the reader who wish to integrate imgui_impl_vulkan.cpp/.h in their own engine/app.
+// - Common ImGui_ImplVulkan_XXXX functions and structures are used to interface with imgui_impl_vulkan.cpp/.h.
+//   You will use those if you want to use this rendering back-end in your engine/app.
+// - Helper ImGui_ImplVulkanH_XXXX functions and structures are only used by this example (main.cpp) and by 
+//   the back-end itself (imgui_impl_vulkan.cpp), but should PROBABLY NOT be used by your own engine/app code.
+// Read comments in imgui_impl_vulkan.h.
+
 #pragma once
 
 #include <vulkan/vulkan.h>
 
-#define IMGUI_VK_QUEUED_FRAMES      2
-
-// Please zero-clear before use.
+// Initialization data, for ImGui_ImplVulkan_Init()
+// [Please zero-clear before use!]
 struct ImGui_ImplVulkan_InitInfo
 {
-    VkInstance                      Instance;
-    VkPhysicalDevice                PhysicalDevice;
-    VkDevice                        Device;
-    uint32_t                        QueueFamily;
-    VkQueue                         Queue;
-    VkPipelineCache                 PipelineCache;
-    VkDescriptorPool                DescriptorPool;
-    const VkAllocationCallbacks*    Allocator;
-    void                            (*CheckVkResultFn)(VkResult err);
+    VkInstance          Instance;
+    VkPhysicalDevice    PhysicalDevice;
+    VkDevice            Device;
+    uint32_t            QueueFamily;
+    VkQueue             Queue;
+    VkPipelineCache     PipelineCache;
+    VkDescriptorPool    DescriptorPool;
+    int                 MinImageCount;          // >= 2
+    const VkAllocationCallbacks* Allocator;
+    void                (*CheckVkResultFn)(VkResult err);
+};
+
+// Reusable buffers used for rendering by current in-flight frame, for ImGui_ImplVulkan_RenderDrawData()
+// [Please zero-clear before use!]
+// In the examples we store those in the helper ImGui_ImplVulkanH_FrameData structure, however as your own engine/app likely won't use the ImGui_Impl_VulkanH_XXXX helpers,
+// you are expected to hold on as many ImGui_ImplVulkan_FrameRenderBuffers structures on your side as you have in-flight frames (== init_info.FramesQueueSize)
+struct ImGui_ImplVulkan_FrameRenderBuffers
+{
+    VkDeviceMemory      VertexBufferMemory;
+    VkDeviceMemory      IndexBufferMemory;
+    VkDeviceSize        VertexBufferSize;
+    VkDeviceSize        IndexBufferSize;
+    VkBuffer            VertexBuffer;
+    VkBuffer            IndexBuffer;
 };
 
 // Called by user code
 IMGUI_IMPL_API bool     ImGui_ImplVulkan_Init(ImGui_ImplVulkan_InitInfo* info, VkRenderPass render_pass);
 IMGUI_IMPL_API void     ImGui_ImplVulkan_Shutdown();
 IMGUI_IMPL_API void     ImGui_ImplVulkan_NewFrame();
-IMGUI_IMPL_API void     ImGui_ImplVulkan_RenderDrawData(ImDrawData* draw_data, VkCommandBuffer command_buffer);
+IMGUI_IMPL_API void     ImGui_ImplVulkan_RenderDrawData(ImDrawData* draw_data, VkCommandBuffer command_buffer, ImGui_ImplVulkan_FrameRenderBuffers* buffers);
 IMGUI_IMPL_API bool     ImGui_ImplVulkan_CreateFontsTexture(VkCommandBuffer command_buffer);
-IMGUI_IMPL_API void     ImGui_ImplVulkan_InvalidateFontUploadObjects();
+IMGUI_IMPL_API void     ImGui_ImplVulkan_DestroyFontUploadObjects();
+IMGUI_IMPL_API void     ImGui_ImplVulkan_DestroyFrameRenderBuffers(VkInstance instance, VkDevice device, ImGui_ImplVulkan_FrameRenderBuffers* buffers, const VkAllocationCallbacks* allocator);
+IMGUI_IMPL_API void     ImGui_ImplVulkan_SetSwapChainMinImageCount(int frames_queue_size); // To override MinImageCount after initialization
 
-// Called by ImGui_ImplVulkan_Init() might be useful elsewhere.
+// Called by ImGui_ImplVulkan_Init(), might be useful elsewhere.
 IMGUI_IMPL_API bool     ImGui_ImplVulkan_CreateDeviceObjects();
-IMGUI_IMPL_API void     ImGui_ImplVulkan_InvalidateDeviceObjects();
+IMGUI_IMPL_API void     ImGui_ImplVulkan_DestroyDeviceObjects();
 
 
 //-------------------------------------------------------------------------
 // Internal / Miscellaneous Vulkan Helpers
-// (Used by example's main.cpp. Used by multi-viewport features. Probably NOT used by your own app.)
+// (Used by example's main.cpp. Used by multi-viewport features. PROBABLY NOT used by your own engine/app.)
 //-------------------------------------------------------------------------
 // You probably do NOT need to use or care about those functions.
 // Those functions only exist because:
@@ -55,38 +78,42 @@ IMGUI_IMPL_API void     ImGui_ImplVulkan_InvalidateDeviceObjects();
 //   2) the multi-viewport / platform window implementation needs them internally.
 // Generally we avoid exposing any kind of superfluous high-level helpers in the bindings,
 // but it is too much code to duplicate everywhere so we exceptionally expose them.
-// Your application/engine will likely already have code to setup all that stuff (swap chain, render pass, frame buffers, etc.).
+//
+// Your engine/app will likely _already_ have code to setup all that stuff (swap chain, render pass, frame buffers, etc.).
 // You may read this code to learn about Vulkan, but it is recommended you use you own custom tailored code to do equivalent work.
-// (those functions do not interact with any of the state used by the regular ImGui_ImplVulkan_XXX functions)
+// (The ImGui_ImplVulkanH_XXX functions do not interact with any of the state used by the regular ImGui_ImplVulkan_XXX functions)
 //-------------------------------------------------------------------------
 
-struct ImGui_ImplVulkanH_FrameData;
-struct ImGui_ImplVulkanH_WindowData;
+struct ImGui_ImplVulkanH_Frame;
+struct ImGui_ImplVulkanH_Window;
 
-IMGUI_IMPL_API void                 ImGui_ImplVulkanH_CreateWindowDataCommandBuffers(VkPhysicalDevice physical_device, VkDevice device, uint32_t queue_family, ImGui_ImplVulkanH_WindowData* wd, const VkAllocationCallbacks* allocator);
-IMGUI_IMPL_API void                 ImGui_ImplVulkanH_CreateWindowDataSwapChainAndFramebuffer(VkPhysicalDevice physical_device, VkDevice device, ImGui_ImplVulkanH_WindowData* wd, const VkAllocationCallbacks* allocator, int w, int h);
-IMGUI_IMPL_API void                 ImGui_ImplVulkanH_DestroyWindowData(VkInstance instance, VkDevice device, ImGui_ImplVulkanH_WindowData* wd, const VkAllocationCallbacks* allocator);
+// Helpers
+IMGUI_IMPL_API void                 ImGui_ImplVulkanH_CreateWindow(VkInstance instance, VkPhysicalDevice physical_device, VkDevice device, ImGui_ImplVulkanH_Window* wnd, uint32_t queue_family, const VkAllocationCallbacks* allocator, int w, int h, uint32_t min_image_count);
+IMGUI_IMPL_API void                 ImGui_ImplVulkanH_DestroyWindow(VkInstance instance, VkDevice device, ImGui_ImplVulkanH_Window* wnd, const VkAllocationCallbacks* allocator);
 IMGUI_IMPL_API VkSurfaceFormatKHR   ImGui_ImplVulkanH_SelectSurfaceFormat(VkPhysicalDevice physical_device, VkSurfaceKHR surface, const VkFormat* request_formats, int request_formats_count, VkColorSpaceKHR request_color_space);
 IMGUI_IMPL_API VkPresentModeKHR     ImGui_ImplVulkanH_SelectPresentMode(VkPhysicalDevice physical_device, VkSurfaceKHR surface, const VkPresentModeKHR* request_modes, int request_modes_count);
 IMGUI_IMPL_API int                  ImGui_ImplVulkanH_GetMinImageCountFromPresentMode(VkPresentModeKHR present_mode);
 
 // Helper structure to hold the data needed by one rendering frame
-// (Used by example's main.cpp. Used by multi-viewport features. Probably NOT used by your own app.)
-struct ImGui_ImplVulkanH_FrameData
+// (Used by example's main.cpp. Used by multi-viewport features. Probably NOT used by your own engine/app.)
+// [Please zero-clear before use!]
+struct ImGui_ImplVulkanH_Frame
 {
-    uint32_t            BackbufferIndex;        // Keep track of recently rendered swapchain frame indices
     VkCommandPool       CommandPool;
     VkCommandBuffer     CommandBuffer;
     VkFence             Fence;
     VkSemaphore         ImageAcquiredSemaphore;
     VkSemaphore         RenderCompleteSemaphore;
-
-    IMGUI_IMPL_API ImGui_ImplVulkanH_FrameData();
+    VkImage             Backbuffer;
+    VkImageView         BackbufferView;
+    uint32_t            BackbufferCurrentIndex;
+    VkFramebuffer       Framebuffer;
+    ImGui_ImplVulkan_FrameRenderBuffers RenderBuffers;
 };
 
 // Helper structure to hold the data needed by one rendering context into one OS window
-// (Used by example's main.cpp. Used by multi-viewport features. Probably NOT used by your own app.)
-struct ImGui_ImplVulkanH_WindowData
+// (Used by example's main.cpp. Used by multi-viewport features. Probably NOT used by your own engine/app.)
+struct ImGui_ImplVulkanH_Window
 {
     int                 Width;
     int                 Height;
@@ -97,13 +124,15 @@ struct ImGui_ImplVulkanH_WindowData
     VkRenderPass        RenderPass;
     bool                ClearEnable;
     VkClearValue        ClearValue;
-    uint32_t            BackBufferCount;
-    VkImage             BackBuffer[16];
-    VkImageView         BackBufferView[16];
-    VkFramebuffer       Framebuffer[16];
-    uint32_t            FrameIndex;
-    ImGui_ImplVulkanH_FrameData Frames[IMGUI_VK_QUEUED_FRAMES];
-
-    IMGUI_IMPL_API ImGui_ImplVulkanH_WindowData();
+    uint32_t            FrameIndex;             // Current frame being rendered to (0 <= FrameIndex < FrameInFlightCount)
+    uint32_t            FramesQueueSize;        // Number of simultaneous in-flight frames (returned by vkGetSwapchainImagesKHR, usually derived from min_image_count)
+    ImGui_ImplVulkanH_Frame* Frames;
+
+    ImGui_ImplVulkanH_Window() 
+    { 
+        memset(this, 0, sizeof(*this)); 
+        PresentMode = VK_PRESENT_MODE_MAX_ENUM_KHR;
+        ClearEnable = true;
+    }
 };