Backends: Vulkan: added ImGui_ImplVulkan_CreateMainPipeline(). (#8110, #8111, #8053)

- Added ImGui_ImplVulkan_CreateMainPipeline(...) to explicitly re-create the main window pipeline (when some of its properties are changed).
- Does not implicitly use ImGui_ImplVulkan_InitInfo::PipelineRenderingCreateInfo, but a function parameter.
- The main window pipeline is created only if possible during ImGui_ImplVulkan_Init(...) (if a render pass or rendering info are given), else it should be created with ImGui_ImplVulkan_ReCreateMainPipeline(...)
- ImGui_ImplVulkan_CreatePipeline now takes a struct rather than (too) many parameters (and returns the created pipeline).

backends/imgui_impl_vulkan.h

@@ -65,6 +65,12 @@
 // Backend uses a small number of descriptors per font atlas + as many as additional calls done to ImGui_ImplVulkan_AddTexture().
 #define IMGUI_IMPL_VULKAN_MINIMUM_IMAGE_SAMPLER_POOL_SIZE   (8)     // Minimum per atlas
 
+#ifdef IMGUI_IMPL_VULKAN_HAS_DYNAMIC_RENDERING
+typedef VkPipelineRenderingCreateInfoKHR ImGui_ImplVulkan_PipelineRenderingCreateInfo;
+#else
+typedef void ImGui_ImplVulkan_PipelineRenderingCreateInfo;
+#endif
+
 // Initialization data, for ImGui_ImplVulkan_Init()
 // [Please zero-clear before use!]
 // - About descriptor pool:
@@ -98,6 +104,7 @@ struct ImGui_ImplVulkan_InitInfo
     // Need to explicitly enable VK_KHR_dynamic_rendering extension to use this, even for Vulkan 1.3.
     bool                            UseDynamicRendering;
 #ifdef IMGUI_IMPL_VULKAN_HAS_DYNAMIC_RENDERING
+    // (Optional, valid iif .sType == VK_STRUCTURE_TYPE_PIPELINE_RENDERING_CREATE_INFO_KHR)
     VkPipelineRenderingCreateInfoKHR PipelineRenderingCreateInfo;
 #endif
 
@@ -108,12 +115,22 @@ struct ImGui_ImplVulkan_InitInfo
 };
 
 // Follow "Getting Started" link and check examples/ folder to learn about using backends!
-IMGUI_IMPL_API bool             ImGui_ImplVulkan_Init(ImGui_ImplVulkan_InitInfo* info);
+IMGUI_IMPL_API bool             ImGui_ImplVulkan_Init(ImGui_ImplVulkan_InitInfo* info); // The main pipeline will be created if possible (RenderPass xor (UseDynamicRendering && PipelineRenderingCreateInfo->sType is correct))
+#define IMGUI_IMPL_VULKAN_HAS_MAIN_PIPELINE_RE_CREATION 1
+struct ImGui_ImplVulkan_MainPipelineCreateInfo
+{
+    VkRenderPass                    RenderPass = VK_NULL_HANDLE;
+    uint32_t                        Subpass = 0;
+    VkSampleCountFlagBits           MSAASamples = {};
+    const ImGui_ImplVulkan_PipelineRenderingCreateInfo* pDynamicRendering = nullptr;
+};
+IMGUI_IMPL_API void             ImGui_ImplVulkan_ReCreateMainPipeline(ImGui_ImplVulkan_MainPipelineCreateInfo const& info); // (render_pass xor (p_dynamic_rendering && p_dynamic_rendering is correct (sType and pNext))
 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, VkPipeline pipeline = VK_NULL_HANDLE);
 IMGUI_IMPL_API void             ImGui_ImplVulkan_SetMinImageCount(uint32_t min_image_count); // To override MinImageCount after initialization (e.g. if swap chain is recreated)
 
+
 // (Advanced) Use e.g. if you need to precisely control the timing of texture updates (e.g. for staged rendering), by setting ImDrawData::Textures = NULL to handle this manually.
 IMGUI_IMPL_API void             ImGui_ImplVulkan_UpdateTexture(ImTextureData* tex);