backends/imgui_impl_vulkan.h

// dear imgui: Renderer Backend for Vulkan
// This needs to be used along with a Platform Backend (e.g. GLFW, SDL, Win32, custom..)

// Implemented features:
//  [X] Renderer: Support for large meshes (64k+ vertices) with 16-bit indices.
// Missing features:
//  [ ] Renderer: User texture binding. Changes of ImTextureID aren't supported by this backend! See https://github.com/ocornut/imgui/pull/914

// You can use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this. 
// Prefer including the entire imgui/ repository into your project (either as a copy or as a submodule), and only build the backends you need.
// If you are new to Dear ImGui, read documentation from the docs/ folder + read the top of imgui.cpp.
// Read online: https://github.com/ocornut/imgui/tree/master/docs

// 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_XXX functions and structures are used to interface with imgui_impl_vulkan.cpp/.h.
//   You will use those if you want to use this rendering backend in your engine/app.
// - Helper ImGui_ImplVulkanH_XXX functions and structures are only used by this example (main.cpp) and by
//   the backend 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 "imgui.h"      // IMGUI_IMPL_API

// [Configuration] in order to use a custom Vulkan function loader:
// (1) You'll need to disable default Vulkan function prototypes.
//     We provide a '#define IMGUI_IMPL_VULKAN_NO_PROTOTYPES' convenience configuration flag.
//     In order to make sure this is visible from the imgui_impl_vulkan.cpp compilation unit:
//     - Add '#define IMGUI_IMPL_VULKAN_NO_PROTOTYPES' in your imconfig.h file
//     - Or as a compilation flag in your build system
//     - Or uncomment here (not recommended because you'd be modifying imgui sources!)
//     - Do not simply add it in a .cpp file!
// (2) Call ImGui_ImplVulkan_LoadFunctions() before ImGui_ImplVulkan_Init() with your custom function.
// If you have no idea what this is, leave it alone!
//#define IMGUI_IMPL_VULKAN_NO_PROTOTYPES

// Vulkan includes
#if defined(IMGUI_IMPL_VULKAN_NO_PROTOTYPES) && !defined(VK_NO_PROTOTYPES)
#define VK_NO_PROTOTYPES
#endif
#include <vulkan/vulkan.h>

// 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;
    uint32_t                        Subpass;
    uint32_t                        MinImageCount;          // >= 2
    uint32_t                        ImageCount;             // >= MinImageCount
    VkSampleCountFlagBits           MSAASamples;            // >= VK_SAMPLE_COUNT_1_BIT
    const VkAllocationCallbacks*    Allocator;
    void                            (*CheckVkResultFn)(VkResult err);
};

// 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, VkPipeline pipeline = VK_NULL_HANDLE);
IMGUI_IMPL_API bool     ImGui_ImplVulkan_CreateFontsTexture(VkCommandBuffer command_buffer);
IMGUI_IMPL_API void     ImGui_ImplVulkan_DestroyFontUploadObjects();
IMGUI_IMPL_API void     ImGui_ImplVulkan_SetMinImageCount(uint32_t min_image_count); // To override MinImageCount after initialization (e.g. if swap chain is recreated)

// Optional: load Vulkan functions with a custom function loader
// This is only useful with IMGUI_IMPL_VULKAN_NO_PROTOTYPES / VK_NO_PROTOTYPES
IMGUI_IMPL_API bool     ImGui_ImplVulkan_LoadFunctions(PFN_vkVoidFunction(*loader_func)(const char* function_name, void* user_data), void* user_data = NULL);

//-------------------------------------------------------------------------
// Internal / Miscellaneous Vulkan Helpers
// (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 upcoming multi-viewport feature will need them internally.
// 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)
//-------------------------------------------------------------------------

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_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 engine/app.)
// [Please zero-clear before use!]
struct ImGui_ImplVulkanH_Frame
{
    VkCommandPool       CommandPool;
    VkCommandBuffer     CommandBuffer;
    VkFence             Fence;
    VkImage             Backbuffer;
    VkImageView         BackbufferView;
    VkFramebuffer       Framebuffer;
};

struct ImGui_ImplVulkanH_FrameSemaphores
{
    VkSemaphore         ImageAcquiredSemaphore;
    VkSemaphore         RenderCompleteSemaphore;
};

// 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 engine/app.)
struct ImGui_ImplVulkanH_Window
{
    int                 Width;
    int                 Height;
    VkSwapchainKHR      Swapchain;
    VkSurfaceKHR        Surface;
    VkSurfaceFormatKHR  SurfaceFormat;
    VkPresentModeKHR    PresentMode;
    VkRenderPass        RenderPass;
    VkPipeline          Pipeline;               // The window pipeline may uses a different VkRenderPass than the one passed in ImGui_ImplVulkan_InitInfo
    bool                ClearEnable;
    VkClearValue        ClearValue;
    uint32_t            FrameIndex;             // Current frame being rendered to (0 <= FrameIndex < FrameInFlightCount)
    uint32_t            ImageCount;             // Number of simultaneous in-flight frames (returned by vkGetSwapchainImagesKHR, usually derived from min_image_count)
    uint32_t            SemaphoreIndex;         // Current set of swapchain wait semaphores we're using (needs to be distinct from per frame data)
    ImGui_ImplVulkanH_Frame*            Frames;
    ImGui_ImplVulkanH_FrameSemaphores*  FrameSemaphores;

    ImGui_ImplVulkanH_Window()
    {
        memset(this, 0, sizeof(*this));
        PresentMode = VK_PRESENT_MODE_MAX_ENUM_KHR;
        ClearEnable = true;
    }
};