Backends: Vulkan: moved helpers to backend: ImGui_ImplVulkanH_SelectPhysicalDevice(), ImGui_ImplVulkanH_SelectQueueFamilyIndex(). (#8180)

backends/imgui_impl_vulkan.cpp

@@ -26,6 +26,7 @@
 
 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
+//  2025-01-06: Vulkan: Added more ImGui_ImplVulkanH_XXXX helper functions to simplify our examples.
 //  2024-12-11: Vulkan: Fixed setting VkSwapchainCreateInfoKHR::preTransform for platforms not supporting VK_SURFACE_TRANSFORM_IDENTITY_BIT_KHR. (#8222)
 //  2024-11-27: Vulkan: Make user-provided descriptor pool optional. As a convenience, when setting init_info->DescriptorPoolSize the backend will create one itself. (#8172, #4867)
 //  2024-10-07: Vulkan: Changed default texture sampler to Clamp instead of Repeat/Wrap.
@@ -1334,6 +1335,49 @@ VkPresentModeKHR ImGui_ImplVulkanH_SelectPresentMode(VkPhysicalDevice physical_d
     return VK_PRESENT_MODE_FIFO_KHR; // Always available
 }
 
+VkPhysicalDevice ImGui_ImplVulkanH_SelectPhysicalDevice(VkInstance instance)
+{
+    uint32_t gpu_count;
+    VkResult err = vkEnumeratePhysicalDevices(instance, &gpu_count, nullptr);
+    check_vk_result(err);
+    IM_ASSERT(gpu_count > 0);
+
+    ImVector<VkPhysicalDevice> gpus;
+    gpus.resize(gpu_count);
+    err = vkEnumeratePhysicalDevices(instance, &gpu_count, gpus.Data);
+    check_vk_result(err);
+
+    // If a number >1 of GPUs got reported, find discrete GPU if present, or use first one available. This covers
+    // most common cases (multi-gpu/integrated+dedicated graphics). Handling more complicated setups (multiple
+    // dedicated GPUs) is out of scope of this sample.
+    for (VkPhysicalDevice& device : gpus)
+    {
+        VkPhysicalDeviceProperties properties;
+        vkGetPhysicalDeviceProperties(device, &properties);
+        if (properties.deviceType == VK_PHYSICAL_DEVICE_TYPE_DISCRETE_GPU)
+            return device;
+    }
+
+    // Use first GPU (Integrated) is a Discrete one is not available.
+    if (gpu_count > 0)
+        return gpus[0];
+    return VK_NULL_HANDLE;
+}
+
+
+uint32_t ImGui_ImplVulkanH_SelectQueueFamilyIndex(VkPhysicalDevice physical_device)
+{
+    uint32_t count;
+    vkGetPhysicalDeviceQueueFamilyProperties(physical_device, &count, nullptr);
+    ImVector<VkQueueFamilyProperties> queues_properties;
+    queues_properties.resize((int)count);
+    vkGetPhysicalDeviceQueueFamilyProperties(physical_device, &count, queues_properties.Data);
+    for (uint32_t i = 0; i < count; i++)
+        if (queues_properties[i].queueFlags & VK_QUEUE_GRAPHICS_BIT)
+            return i;
+    return (uint32_t)-1;
+}
+
 void ImGui_ImplVulkanH_CreateWindowCommandBuffers(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);

backends/imgui_impl_vulkan.h

@@ -135,18 +135,24 @@ struct ImGui_ImplVulkan_RenderState
 
 //-------------------------------------------------------------------------
 // Internal / Miscellaneous Vulkan Helpers
-// (Used by example's main.cpp. Used by multi-viewport features. PROBABLY NOT used by your own engine/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:
 //   1) they facilitate the readability and maintenance of the multiple main.cpp examples files.
 //   2) the multi-viewport / platform window implementation needs them internally.
-// Generally we avoid exposing any kind of superfluous high-level helpers in the bindings,
+// Generally we avoid exposing any kind of superfluous high-level helpers in the backends,
 // but it is too much code to duplicate everywhere so we exceptionally expose them.
 //
-// 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.
-// (The ImGui_ImplVulkanH_XXX functions do not interact with any of the state used by the regular ImGui_ImplVulkan_XXX functions)
+// 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 if you are curious, but
+// it is recommended you use you own custom tailored code to do equivalent work.
+//
+// We don't provide a strong guarantee that we won't change those functions API.
+//
+// The ImGui_ImplVulkanH_XXX functions should NOT interact with any of the state used
+// by the regular ImGui_ImplVulkan_XXX functions).
 //-------------------------------------------------------------------------
 
 struct ImGui_ImplVulkanH_Frame;
@@ -157,6 +163,8 @@ IMGUI_IMPL_API void                 ImGui_ImplVulkanH_CreateOrResizeWindow(VkIns
 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 VkPhysicalDevice     ImGui_ImplVulkanH_SelectPhysicalDevice(VkInstance instance);
+IMGUI_IMPL_API uint32_t             ImGui_ImplVulkanH_SelectQueueFamilyIndex(VkPhysicalDevice physical_device);
 IMGUI_IMPL_API int                  ImGui_ImplVulkanH_GetMinImageCountFromPresentMode(VkPresentModeKHR present_mode);
 
 // Helper structure to hold the data needed by one rendering frame

docs/CHANGELOG.txt

@@ -70,6 +70,8 @@ Other changes:
 - Backends: Metal: Fixed resource leak when using multiple contexts. (#7419) [@anszom]
 - Backends: Vulkan: Fixed setting VkSwapchainCreateInfoKHR::preTransform for
   platforms not supporting VK_SURFACE_TRANSFORM_IDENTITY_BIT_KHR. (#8222) [@Zer0xFF]
+- Backends: Vulkan: Added a few more ImGui_ImplVulkanH_XXX helper functions
+  primarily for the purpose of making our examples simpler.
 
 
 -----------------------------------------------------------------------

examples/example_glfw_vulkan/main.cpp

@@ -85,35 +85,6 @@ static bool IsExtensionAvailable(const ImVector<VkExtensionProperties>& properti
     return false;
 }
 
-static VkPhysicalDevice SetupVulkan_SelectPhysicalDevice()
-{
-    uint32_t gpu_count;
-    VkResult err = vkEnumeratePhysicalDevices(g_Instance, &gpu_count, nullptr);
-    check_vk_result(err);
-    IM_ASSERT(gpu_count > 0);
-
-    ImVector<VkPhysicalDevice> gpus;
-    gpus.resize(gpu_count);
-    err = vkEnumeratePhysicalDevices(g_Instance, &gpu_count, gpus.Data);
-    check_vk_result(err);
-
-    // If a number >1 of GPUs got reported, find discrete GPU if present, or use first one available. This covers
-    // most common cases (multi-gpu/integrated+dedicated graphics). Handling more complicated setups (multiple
-    // dedicated GPUs) is out of scope of this sample.
-    for (VkPhysicalDevice& device : gpus)
-    {
-        VkPhysicalDeviceProperties properties;
-        vkGetPhysicalDeviceProperties(device, &properties);
-        if (properties.deviceType == VK_PHYSICAL_DEVICE_TYPE_DISCRETE_GPU)
-            return device;
-    }
-
-    // Use first GPU (Integrated) is a Discrete one is not available.
-    if (gpu_count > 0)
-        return gpus[0];
-    return VK_NULL_HANDLE;
-}
-
 static void SetupVulkan(ImVector<const char*> instance_extensions)
 {
     VkResult err;
@@ -177,23 +148,12 @@ static void SetupVulkan(ImVector<const char*> instance_extensions)
     }
 
     // Select Physical Device (GPU)
-    g_PhysicalDevice = SetupVulkan_SelectPhysicalDevice();
+    g_PhysicalDevice = ImGui_ImplVulkanH_SelectPhysicalDevice(g_Instance);
+    IM_ASSERT(g_PhysicalDevice != VK_NULL_HANDLE);
 
     // Select graphics queue family
-    {
-        uint32_t count;
-        vkGetPhysicalDeviceQueueFamilyProperties(g_PhysicalDevice, &count, nullptr);
-        VkQueueFamilyProperties* queues = (VkQueueFamilyProperties*)malloc(sizeof(VkQueueFamilyProperties) * count);
-        vkGetPhysicalDeviceQueueFamilyProperties(g_PhysicalDevice, &count, queues);
-        for (uint32_t i = 0; i < count; i++)
-            if (queues[i].queueFlags & VK_QUEUE_GRAPHICS_BIT)
-            {
-                g_QueueFamily = i;
-                break;
-            }
-        free(queues);
-        IM_ASSERT(g_QueueFamily != (uint32_t)-1);
-    }
+    g_QueueFamily = ImGui_ImplVulkanH_SelectQueueFamilyIndex(g_PhysicalDevice);
+    IM_ASSERT(g_QueueFamily != (uint32_t)-1);
 
     // Create Logical Device (with 1 queue)
     {

examples/example_sdl2_opengl3/main.cpp

@@ -87,7 +87,7 @@ int main(int, char**)
         printf("Error: SDL_GL_CreateContext(): %s\n", SDL_GetError());
         return -1;
     }
-    
+
     SDL_GL_MakeCurrent(window, gl_context);
     SDL_GL_SetSwapInterval(1); // Enable vsync
 

examples/example_sdl2_vulkan/main.cpp

@@ -73,35 +73,6 @@ static bool IsExtensionAvailable(const ImVector<VkExtensionProperties>& properti
     return false;
 }
 
-static VkPhysicalDevice SetupVulkan_SelectPhysicalDevice()
-{
-    uint32_t gpu_count;
-    VkResult err = vkEnumeratePhysicalDevices(g_Instance, &gpu_count, nullptr);
-    check_vk_result(err);
-    IM_ASSERT(gpu_count > 0);
-
-    ImVector<VkPhysicalDevice> gpus;
-    gpus.resize(gpu_count);
-    err = vkEnumeratePhysicalDevices(g_Instance, &gpu_count, gpus.Data);
-    check_vk_result(err);
-
-    // If a number >1 of GPUs got reported, find discrete GPU if present, or use first one available. This covers
-    // most common cases (multi-gpu/integrated+dedicated graphics). Handling more complicated setups (multiple
-    // dedicated GPUs) is out of scope of this sample.
-    for (VkPhysicalDevice& device : gpus)
-    {
-        VkPhysicalDeviceProperties properties;
-        vkGetPhysicalDeviceProperties(device, &properties);
-        if (properties.deviceType == VK_PHYSICAL_DEVICE_TYPE_DISCRETE_GPU)
-            return device;
-    }
-
-    // Use first GPU (Integrated) is a Discrete one is not available.
-    if (gpu_count > 0)
-        return gpus[0];
-    return VK_NULL_HANDLE;
-}
-
 static void SetupVulkan(ImVector<const char*> instance_extensions)
 {
     VkResult err;
@@ -165,23 +136,12 @@ static void SetupVulkan(ImVector<const char*> instance_extensions)
     }
 
     // Select Physical Device (GPU)
-    g_PhysicalDevice = SetupVulkan_SelectPhysicalDevice();
+    g_PhysicalDevice = ImGui_ImplVulkanH_SelectPhysicalDevice(g_Instance);
+    IM_ASSERT(g_PhysicalDevice != VK_NULL_HANDLE);
 
     // Select graphics queue family
-    {
-        uint32_t count;
-        vkGetPhysicalDeviceQueueFamilyProperties(g_PhysicalDevice, &count, nullptr);
-        VkQueueFamilyProperties* queues = (VkQueueFamilyProperties*)malloc(sizeof(VkQueueFamilyProperties) * count);
-        vkGetPhysicalDeviceQueueFamilyProperties(g_PhysicalDevice, &count, queues);
-        for (uint32_t i = 0; i < count; i++)
-            if (queues[i].queueFlags & VK_QUEUE_GRAPHICS_BIT)
-            {
-                g_QueueFamily = i;
-                break;
-            }
-        free(queues);
-        IM_ASSERT(g_QueueFamily != (uint32_t)-1);
-    }
+    g_QueueFamily = ImGui_ImplVulkanH_SelectQueueFamilyIndex(g_PhysicalDevice);
+    IM_ASSERT(g_QueueFamily != (uint32_t)-1);
 
     // Create Logical Device (with 1 queue)
     {

examples/example_sdl3_vulkan/main.cpp

@@ -78,35 +78,6 @@ static bool IsExtensionAvailable(const ImVector<VkExtensionProperties>& properti
     return false;
 }
 
-static VkPhysicalDevice SetupVulkan_SelectPhysicalDevice()
-{
-    uint32_t gpu_count;
-    VkResult err = vkEnumeratePhysicalDevices(g_Instance, &gpu_count, nullptr);
-    check_vk_result(err);
-    IM_ASSERT(gpu_count > 0);
-
-    ImVector<VkPhysicalDevice> gpus;
-    gpus.resize(gpu_count);
-    err = vkEnumeratePhysicalDevices(g_Instance, &gpu_count, gpus.Data);
-    check_vk_result(err);
-
-    // If a number >1 of GPUs got reported, find discrete GPU if present, or use first one available. This covers
-    // most common cases (multi-gpu/integrated+dedicated graphics). Handling more complicated setups (multiple
-    // dedicated GPUs) is out of scope of this sample.
-    for (VkPhysicalDevice& device : gpus)
-    {
-        VkPhysicalDeviceProperties properties;
-        vkGetPhysicalDeviceProperties(device, &properties);
-        if (properties.deviceType == VK_PHYSICAL_DEVICE_TYPE_DISCRETE_GPU)
-            return device;
-    }
-
-    // Use first GPU (Integrated) is a Discrete one is not available.
-    if (gpu_count > 0)
-        return gpus[0];
-    return VK_NULL_HANDLE;
-}
-
 static void SetupVulkan(ImVector<const char*> instance_extensions)
 {
     VkResult err;
@@ -170,23 +141,12 @@ static void SetupVulkan(ImVector<const char*> instance_extensions)
     }
 
     // Select Physical Device (GPU)
-    g_PhysicalDevice = SetupVulkan_SelectPhysicalDevice();
+    g_PhysicalDevice = ImGui_ImplVulkanH_SelectPhysicalDevice(g_Instance);
+    IM_ASSERT(g_PhysicalDevice != VK_NULL_HANDLE);
 
     // Select graphics queue family
-    {
-        uint32_t count;
-        vkGetPhysicalDeviceQueueFamilyProperties(g_PhysicalDevice, &count, nullptr);
-        VkQueueFamilyProperties* queues = (VkQueueFamilyProperties*)malloc(sizeof(VkQueueFamilyProperties) * count);
-        vkGetPhysicalDeviceQueueFamilyProperties(g_PhysicalDevice, &count, queues);
-        for (uint32_t i = 0; i < count; i++)
-            if (queues[i].queueFlags & VK_QUEUE_GRAPHICS_BIT)
-            {
-                g_QueueFamily = i;
-                break;
-            }
-        free(queues);
-        IM_ASSERT(g_QueueFamily != (uint32_t)-1);
-    }
+    g_QueueFamily = ImGui_ImplVulkanH_SelectQueueFamilyIndex(g_PhysicalDevice);
+    IM_ASSERT(g_QueueFamily != (uint32_t)-1);
 
     // Create Logical Device (with 1 queue)
     {