(Breaking) Backends: Vulkan: added 'VkImageUsageFlags image_usage' parameter to ImGui_ImplVulkanH_CreateOrResizeWindow(). (#8946, #8110, #8111, #8686)

Default to VK_IMAGE_USAGE_COLOR_ATTACHMENT_BIT.

backends/imgui_impl_vulkan.cpp

@@ -27,6 +27,7 @@
 
 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
+//  2025-09-26: *BREAKING CHANGE*: helper ImGui_ImplVulkanH_CreateOrResizeWindow() added a VkImageUsageFlags image_usage` argument, default to VK_IMAGE_USAGE_COLOR_ATTACHMENT_BIT if 0.
 //  2025-09-26: Vulkan: Added a way to customize shaders by filling ImGui_ImplVulkan_InitInfo::CustomShaderVertCreateInfo/CustomShaderFragCreateInfo. (#8585)
 //  2025-09-18: Call platform_io.ClearRendererHandlers() on shutdown.
 //  2025-09-04: Vulkan: Added ImGui_ImplVulkan_CreateMainPipeline(). (#8110, #8111)
@@ -118,7 +119,7 @@ void ImGui_ImplVulkan_DestroyFrameRenderBuffers(VkDevice device, ImGui_ImplVulka
 void ImGui_ImplVulkan_DestroyWindowRenderBuffers(VkDevice device, ImGui_ImplVulkan_WindowRenderBuffers* buffers, const VkAllocationCallbacks* allocator);
 void ImGui_ImplVulkanH_DestroyFrame(VkDevice device, ImGui_ImplVulkanH_Frame* fd, const VkAllocationCallbacks* allocator);
 void ImGui_ImplVulkanH_DestroyFrameSemaphores(VkDevice device, ImGui_ImplVulkanH_FrameSemaphores* fsd, const VkAllocationCallbacks* allocator);
-void ImGui_ImplVulkanH_CreateWindowSwapChain(VkPhysicalDevice physical_device, VkDevice device, ImGui_ImplVulkanH_Window* wd, const VkAllocationCallbacks* allocator, int w, int h, uint32_t min_image_count);
+void ImGui_ImplVulkanH_CreateWindowSwapChain(VkPhysicalDevice physical_device, VkDevice device, ImGui_ImplVulkanH_Window* wd, const VkAllocationCallbacks* allocator, int w, int h, uint32_t min_image_count, VkImageUsageFlags image_usage);
 void ImGui_ImplVulkanH_CreateWindowCommandBuffers(VkPhysicalDevice physical_device, VkDevice device, ImGui_ImplVulkanH_Window* wd, uint32_t queue_family, const VkAllocationCallbacks* allocator);
 
 // Vulkan prototypes for use with custom loaders
@@ -1605,7 +1606,7 @@ int ImGui_ImplVulkanH_GetMinImageCountFromPresentMode(VkPresentModeKHR present_m
 }
 
 // Also destroy old swap chain and in-flight frames data, if any.
-void ImGui_ImplVulkanH_CreateWindowSwapChain(VkPhysicalDevice physical_device, VkDevice device, ImGui_ImplVulkanH_Window* wd, const VkAllocationCallbacks* allocator, int w, int h, uint32_t min_image_count)
+void ImGui_ImplVulkanH_CreateWindowSwapChain(VkPhysicalDevice physical_device, VkDevice device, ImGui_ImplVulkanH_Window* wd, const VkAllocationCallbacks* allocator, int w, int h, uint32_t min_image_count, VkImageUsageFlags image_usage)
 {
     VkResult err;
     VkSwapchainKHR old_swapchain = wd->Swapchain;
@@ -1644,7 +1645,7 @@ void ImGui_ImplVulkanH_CreateWindowSwapChain(VkPhysicalDevice physical_device, V
         info.imageFormat = wd->SurfaceFormat.format;
         info.imageColorSpace = wd->SurfaceFormat.colorSpace;
         info.imageArrayLayers = 1;
-        info.imageUsage = VK_IMAGE_USAGE_COLOR_ATTACHMENT_BIT;
+        info.imageUsage = (image_usage != 0) ? image_usage : VK_IMAGE_USAGE_COLOR_ATTACHMENT_BIT;
         info.imageSharingMode = VK_SHARING_MODE_EXCLUSIVE;           // Assume that graphics family == present family
         info.preTransform = (cap.supportedTransforms & VK_SURFACE_TRANSFORM_IDENTITY_BIT_KHR) ? VK_SURFACE_TRANSFORM_IDENTITY_BIT_KHR : cap.currentTransform;
         info.compositeAlpha = VK_COMPOSITE_ALPHA_OPAQUE_BIT_KHR;
@@ -1772,11 +1773,12 @@ void ImGui_ImplVulkanH_CreateWindowSwapChain(VkPhysicalDevice physical_device, V
 }
 
 // Create or resize window
-void ImGui_ImplVulkanH_CreateOrResizeWindow(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)
+// - 2025/09/26: v1.92.4 added a trailing 'VkImageUsageFlags image_usage' parameter which is usually VK_IMAGE_USAGE_COLOR_ATTACHMENT_BIT.
+void ImGui_ImplVulkanH_CreateOrResizeWindow(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, VkImageUsageFlags image_usage)
 {
     IM_ASSERT(g_FunctionsLoaded && "Need to call ImGui_ImplVulkan_LoadFunctions() if IMGUI_IMPL_VULKAN_NO_PROTOTYPES or VK_NO_PROTOTYPES are set!");
     (void)instance;
-    ImGui_ImplVulkanH_CreateWindowSwapChain(physical_device, device, wd, allocator, width, height, min_image_count);
+    ImGui_ImplVulkanH_CreateWindowSwapChain(physical_device, device, wd, allocator, width, height, min_image_count, image_usage);
     ImGui_ImplVulkanH_CreateWindowCommandBuffers(physical_device, device, wd, queue_family, allocator);
 
     // FIXME: to submit the command buffer, we need a queue. In the examples folder, the ImGui_ImplVulkanH_CreateOrResizeWindow function is called

backends/imgui_impl_vulkan.h

@@ -181,8 +181,8 @@ struct ImGui_ImplVulkanH_Frame;
 struct ImGui_ImplVulkanH_Window;
 
 // Helpers
-IMGUI_IMPL_API void                 ImGui_ImplVulkanH_CreateOrResizeWindow(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_CreateOrResizeWindow(VkInstance instance, VkPhysicalDevice physical_device, VkDevice device, ImGui_ImplVulkanH_Window* wd, uint32_t queue_family, const VkAllocationCallbacks* allocator, int w, int h, uint32_t min_image_count, VkImageUsageFlags image_usage);
-IMGUI_IMPL_API void                 ImGui_ImplVulkanH_DestroyWindow(VkInstance instance, VkDevice device, ImGui_ImplVulkanH_Window* wnd, const VkAllocationCallbacks* allocator);
+IMGUI_IMPL_API void                 ImGui_ImplVulkanH_DestroyWindow(VkInstance instance, VkDevice device, ImGui_ImplVulkanH_Window* wd, 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);

docs/CHANGELOG.txt

@@ -41,6 +41,12 @@ HOW TO UPDATE?
 
 Breaking Changes:
 
+- Backends: Vulkan: helper ImGui_ImplVulkanH_CreateOrResizeWindow() added a
+  `VkImageUsageFlags image_usage` argument.
+  It was previously hardcoded to `VK_IMAGE_USAGE_COLOR_ATTACHMENT_BIT` and defaults
+  to that when the value is 0. In theory the function is an internal helper but
+  since it's used by our examples some may have used it. (#8946, #8111, #8686)
+
 Other Changes:
 
 - Windows: added lower-right resize grip on child windows using both

examples/example_glfw_vulkan/main.cpp

@@ -54,6 +54,7 @@ static VkDescriptorPool         g_DescriptorPool = VK_NULL_HANDLE;
 static ImGui_ImplVulkanH_Window g_MainWindowData;
 static uint32_t                 g_MinImageCount = 2;
 static bool                     g_SwapChainRebuild = false;
+static VkImageUsageFlags        g_SwapChainImageUsage = VK_IMAGE_USAGE_COLOR_ATTACHMENT_BIT;
 
 static void glfw_error_callback(int error, const char* description)
 {
@@ -239,7 +240,7 @@ static void SetupVulkanWindow(ImGui_ImplVulkanH_Window* wd, VkSurfaceKHR surface
 
     // Create SwapChain, RenderPass, Framebuffer, etc.
     IM_ASSERT(g_MinImageCount >= 2);
-    ImGui_ImplVulkanH_CreateOrResizeWindow(g_Instance, g_PhysicalDevice, g_Device, wd, g_QueueFamily, g_Allocator, width, height, g_MinImageCount);
+    ImGui_ImplVulkanH_CreateOrResizeWindow(g_Instance, g_PhysicalDevice, g_Device, wd, g_QueueFamily, g_Allocator, width, height, g_MinImageCount, g_SwapChainImageUsage);
 }
 
 static void CleanupVulkan()
@@ -456,7 +457,7 @@ int main(int, char**)
         if (fb_width > 0 && fb_height > 0 && (g_SwapChainRebuild || g_MainWindowData.Width != fb_width || g_MainWindowData.Height != fb_height))
         {
             ImGui_ImplVulkan_SetMinImageCount(g_MinImageCount);
-            ImGui_ImplVulkanH_CreateOrResizeWindow(g_Instance, g_PhysicalDevice, g_Device, &g_MainWindowData, g_QueueFamily, g_Allocator, fb_width, fb_height, g_MinImageCount);
+            ImGui_ImplVulkanH_CreateOrResizeWindow(g_Instance, g_PhysicalDevice, g_Device, wd, g_QueueFamily, g_Allocator, fb_width, fb_height, g_MinImageCount, g_SwapChainImageUsage);
             g_MainWindowData.FrameIndex = 0;
             g_SwapChainRebuild = false;
         }

examples/example_sdl2_vulkan/main.cpp

@@ -49,6 +49,7 @@ static VkDescriptorPool         g_DescriptorPool = VK_NULL_HANDLE;
 static ImGui_ImplVulkanH_Window g_MainWindowData;
 static uint32_t                 g_MinImageCount = 2;
 static bool                     g_SwapChainRebuild = false;
+static VkImageUsageFlags        g_SwapChainImageUsage = VK_IMAGE_USAGE_COLOR_ATTACHMENT_BIT;
 
 static void check_vk_result(VkResult err)
 {
@@ -230,7 +231,7 @@ static void SetupVulkanWindow(ImGui_ImplVulkanH_Window* wd, VkSurfaceKHR surface
 
     // Create SwapChain, RenderPass, Framebuffer, etc.
     IM_ASSERT(g_MinImageCount >= 2);
-    ImGui_ImplVulkanH_CreateOrResizeWindow(g_Instance, g_PhysicalDevice, g_Device, wd, g_QueueFamily, g_Allocator, width, height, g_MinImageCount);
+    ImGui_ImplVulkanH_CreateOrResizeWindow(g_Instance, g_PhysicalDevice, g_Device, wd, g_QueueFamily, g_Allocator, width, height, g_MinImageCount, g_SwapChainImageUsage);
 }
 
 static void CleanupVulkan()
@@ -476,7 +477,7 @@ int main(int, char**)
         if (fb_width > 0 && fb_height > 0 && (g_SwapChainRebuild || g_MainWindowData.Width != fb_width || g_MainWindowData.Height != fb_height))
         {
             ImGui_ImplVulkan_SetMinImageCount(g_MinImageCount);
-            ImGui_ImplVulkanH_CreateOrResizeWindow(g_Instance, g_PhysicalDevice, g_Device, &g_MainWindowData, g_QueueFamily, g_Allocator, fb_width, fb_height, g_MinImageCount);
+            ImGui_ImplVulkanH_CreateOrResizeWindow(g_Instance, g_PhysicalDevice, g_Device, wd, g_QueueFamily, g_Allocator, fb_width, fb_height, g_MinImageCount, g_SwapChainImageUsage);
             g_MainWindowData.FrameIndex = 0;
             g_SwapChainRebuild = false;
         }

examples/example_sdl3_vulkan/main.cpp

@@ -51,6 +51,7 @@ static VkDescriptorPool         g_DescriptorPool = VK_NULL_HANDLE;
 static ImGui_ImplVulkanH_Window g_MainWindowData;
 static uint32_t                 g_MinImageCount = 2;
 static bool                     g_SwapChainRebuild = false;
+static VkImageUsageFlags        g_SwapChainImageUsage = VK_IMAGE_USAGE_COLOR_ATTACHMENT_BIT;
 
 static void check_vk_result(VkResult err)
 {
@@ -232,7 +233,7 @@ static void SetupVulkanWindow(ImGui_ImplVulkanH_Window* wd, VkSurfaceKHR surface
 
     // Create SwapChain, RenderPass, Framebuffer, etc.
     IM_ASSERT(g_MinImageCount >= 2);
-    ImGui_ImplVulkanH_CreateOrResizeWindow(g_Instance, g_PhysicalDevice, g_Device, wd, g_QueueFamily, g_Allocator, width, height, g_MinImageCount);
+    ImGui_ImplVulkanH_CreateOrResizeWindow(g_Instance, g_PhysicalDevice, g_Device, wd, g_QueueFamily, g_Allocator, width, height, g_MinImageCount, g_SwapChainImageUsage);
 }
 
 static void CleanupVulkan()
@@ -478,7 +479,7 @@ int main(int, char**)
         if (fb_width > 0 && fb_height > 0 && (g_SwapChainRebuild || g_MainWindowData.Width != fb_width || g_MainWindowData.Height != fb_height))
         {
             ImGui_ImplVulkan_SetMinImageCount(g_MinImageCount);
-            ImGui_ImplVulkanH_CreateOrResizeWindow(g_Instance, g_PhysicalDevice, g_Device, &g_MainWindowData, g_QueueFamily, g_Allocator, fb_width, fb_height, g_MinImageCount);
+            ImGui_ImplVulkanH_CreateOrResizeWindow(g_Instance, g_PhysicalDevice, g_Device, wd, g_QueueFamily, g_Allocator, fb_height, fb_height, g_MinImageCount, g_SwapChainImageUsage);
             g_MainWindowData.FrameIndex = 0;
             g_SwapChainRebuild = false;
         }

examples/example_win32_vulkan/main.cpp

@@ -47,6 +47,7 @@ static VkDescriptorPool         g_DescriptorPool = VK_NULL_HANDLE;
 static ImGui_ImplVulkanH_Window g_MainWindowData;
 static uint32_t                 g_MinImageCount = 2;
 static bool                     g_SwapChainRebuild = false;
+static VkImageUsageFlags        g_SwapChainImageUsage = VK_IMAGE_USAGE_COLOR_ATTACHMENT_BIT;
 
 static void check_vk_result(VkResult err)
 {
@@ -228,7 +229,7 @@ static void SetupVulkanWindow(ImGui_ImplVulkanH_Window* wd, VkSurfaceKHR surface
 
     // Create SwapChain, RenderPass, Framebuffer, etc.
     IM_ASSERT(g_MinImageCount >= 2);
-    ImGui_ImplVulkanH_CreateOrResizeWindow(g_Instance, g_PhysicalDevice, g_Device, wd, g_QueueFamily, g_Allocator, width, height, g_MinImageCount);
+    ImGui_ImplVulkanH_CreateOrResizeWindow(g_Instance, g_PhysicalDevice, g_Device, wd, g_QueueFamily, g_Allocator, width, height, g_MinImageCount, g_SwapChainImageUsage);
 }
 
 static void CleanupVulkan()
@@ -549,7 +550,7 @@ LRESULT WINAPI WndProc(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam)
             if (fb_width > 0 && fb_height > 0 && (g_SwapChainRebuild || g_MainWindowData.Width != fb_width || g_MainWindowData.Height != fb_height))
             {
                 ImGui_ImplVulkan_SetMinImageCount(g_MinImageCount);
-                ImGui_ImplVulkanH_CreateOrResizeWindow(g_Instance, g_PhysicalDevice, g_Device, &g_MainWindowData, g_QueueFamily, g_Allocator, fb_width, fb_height, g_MinImageCount);
+                ImGui_ImplVulkanH_CreateOrResizeWindow(g_Instance, g_PhysicalDevice, g_Device, &g_MainWindowData, g_QueueFamily, g_Allocator, fb_width, fb_height, g_MinImageCount, g_SwapChainImageUsage);
                 g_MainWindowData.FrameIndex = 0;
                 g_SwapChainRebuild = false;
             }