imgui/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:
//  [!] Renderer: User texture binding. Use 'VkDescriptorSet' as texture identifier. Call ImGui_ImplVulkan_AddTexture() to register one. Read the FAQ about ImTextureID/ImTextureRef + https://github.com/ocornut/imgui/pull/914 for discussions.
//  [X] Renderer: Large meshes support (64k+ vertices) even with 16-bit indices (ImGuiBackendFlags_RendererHasVtxOffset).
//  [X] Renderer: Texture updates support for dynamic font atlas (ImGuiBackendFlags_RendererHasTextures).
//  [X] Renderer: Expose selected render state for draw callbacks to use. Access in '(ImGui_ImplXXXX_RenderState*)GetPlatformIO().Renderer_RenderState'.

// 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/

// 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.
// Learn about Dear ImGui:
// - FAQ                  https://dearimgui.com/faq
// - Getting Started      https://dearimgui.com/getting-started
// - Documentation        https://dearimgui.com/docs (same as your local docs/ folder).
// - Introduction, links and more 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_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
#ifndef IMGUI_DISABLE
#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

// Convenience support for Volk
// (you can also technically use IMGUI_IMPL_VULKAN_NO_PROTOTYPES + wrap Volk via ImGui_ImplVulkan_LoadFunctions().)
//#define IMGUI_IMPL_VULKAN_USE_VOLK

#if defined(IMGUI_IMPL_VULKAN_NO_PROTOTYPES) && !defined(VK_NO_PROTOTYPES)
#define VK_NO_PROTOTYPES
#endif
#if defined(VK_USE_PLATFORM_WIN32_KHR) && !defined(NOMINMAX)
#define NOMINMAX
#endif

// Vulkan includes
#ifdef IMGUI_IMPL_VULKAN_USE_VOLK
#include <volk.h>
#else
#include <vulkan/vulkan.h>
#endif
#if defined(VK_VERSION_1_3) || defined(VK_KHR_dynamic_rendering)
#define IMGUI_IMPL_VULKAN_HAS_DYNAMIC_RENDERING
#endif

// 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

// Initialization data, for ImGui_ImplVulkan_Init()
// [Please zero-clear before use!]
// - About descriptor pool:
//   - A VkDescriptorPool should be created with VK_DESCRIPTOR_POOL_CREATE_FREE_DESCRIPTOR_SET_BIT,
//     and must contain a pool size large enough to hold a small number of VK_DESCRIPTOR_TYPE_COMBINED_IMAGE_SAMPLER descriptors.
//   - As an convenience, by setting DescriptorPoolSize > 0 the backend will create one for you.
// - About dynamic rendering:
//   - When using dynamic rendering, set UseDynamicRendering=true and fill PipelineRenderingCreateInfo structure.
struct ImGui_ImplVulkan_InitInfo
{
    uint32_t                        ApiVersion;                 // Fill with API version of Instance, e.g. VK_API_VERSION_1_3 or your value of VkApplicationInfo::apiVersion. May be lower than header version (VK_HEADER_VERSION_COMPLETE)
    VkInstance                      Instance;
    VkPhysicalDevice                PhysicalDevice;
    VkDevice                        Device;
    uint32_t                        QueueFamily;
    VkQueue                         Queue;
    VkDescriptorPool                DescriptorPool;             // See requirements in note above; ignored if using DescriptorPoolSize > 0
    uint32_t                        DescriptorPoolSize;         // Optional: set to create internal descriptor pool automatically instead of using DescriptorPool.
    uint32_t                        MinImageCount;              // >= 2
    uint32_t                        ImageCount;                 // >= MinImageCount
    VkPipelineCache                 PipelineCache;              // Optional

    // Pipeline
    VkRenderPass                    RenderPass;                 // Ignored if using dynamic rendering
    uint32_t                        Subpass;
    VkSampleCountFlagBits           MSAASamples;                // 0 defaults to VK_SAMPLE_COUNT_1_BIT

    // (Optional) Dynamic Rendering
    // Need to explicitly enable VK_KHR_dynamic_rendering extension to use this, even for Vulkan 1.3 + setup PipelineRenderingCreateInfo.
    bool                            UseDynamicRendering;
#ifdef IMGUI_IMPL_VULKAN_HAS_DYNAMIC_RENDERING
    VkPipelineRenderingCreateInfoKHR PipelineRenderingCreateInfo;   // Optional, valid if .sType == VK_STRUCTURE_TYPE_PIPELINE_RENDERING_CREATE_INFO_KHR
#endif

    // (Optional) Allocation, Debugging
    const VkAllocationCallbacks*    Allocator;
    void                            (*CheckVkResultFn)(VkResult err);
    VkDeviceSize                    MinAllocationSize;              // Minimum allocation size. Set to 1024*1024 to satisfy zealous best practices validation layer and waste a little memory.
};

// 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 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 recreate pipeline without reinitializing the backend (see #8110, #8111)
// The main window pipeline will be created by ImGui_ImplVulkan_Init() if possible (== RenderPass xor (UseDynamicRendering && PipelineRenderingCreateInfo->sType == VK_STRUCTURE_TYPE_PIPELINE_RENDERING_CREATE_INFO_KHR))
// Else, the pipeline can be created, or re-created, using ImGui_ImplVulkan_CreateMainPipeline() before rendering.
struct ImGui_ImplVulkan_MainPipelineCreateInfo
{
    VkRenderPass                RenderPass = VK_NULL_HANDLE;
    uint32_t                    Subpass = 0;
    VkSampleCountFlagBits       MSAASamples = {};
#ifdef IMGUI_IMPL_VULKAN_HAS_DYNAMIC_RENDERING
    VkPipelineRenderingCreateInfoKHR PipelineRenderingCreateInfo;   // Optional, valid if .sType == VK_STRUCTURE_TYPE_PIPELINE_RENDERING_CREATE_INFO_KHR
#endif
};
IMGUI_IMPL_API void             ImGui_ImplVulkan_CreateMainPipeline(const ImGui_ImplVulkan_MainPipelineCreateInfo& info); // (render_pass xor (p_dynamic_rendering && p_dynamic_rendering is correct (sType and pNext)))

// (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);

// Register a texture (VkDescriptorSet == ImTextureID)
// FIXME: This is experimental in the sense that we are unsure how to best design/tackle this problem
// Please post to https://github.com/ocornut/imgui/pull/914 if you have suggestions.
IMGUI_IMPL_API VkDescriptorSet  ImGui_ImplVulkan_AddTexture(VkSampler sampler, VkImageView image_view, VkImageLayout image_layout);
IMGUI_IMPL_API void             ImGui_ImplVulkan_RemoveTexture(VkDescriptorSet descriptor_set);

// 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(uint32_t api_version, PFN_vkVoidFunction(*loader_func)(const char* function_name, void* user_data), void* user_data = nullptr);

// [BETA] Selected render state data shared with callbacks.
// This is temporarily stored in GetPlatformIO().Renderer_RenderState during the ImGui_ImplVulkan_RenderDrawData() call.
// (Please open an issue if you feel you need access to more data)
struct ImGui_ImplVulkan_RenderState
{
    VkCommandBuffer     CommandBuffer;
    VkPipeline          Pipeline;
    VkPipelineLayout    PipelineLayout;
};

//-------------------------------------------------------------------------
// 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 multi-viewport / platform window implementation needs 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 if you are curious, but
// it is recommended you use your 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;
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 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
// (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                UseDynamicRendering;
    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            SemaphoreCount;         // Number of simultaneous in-flight frames + 1, to be able to use it in vkAcquireNextImageKHR
    uint32_t            SemaphoreIndex;         // Current set of swapchain wait semaphores we're using (needs to be distinct from per frame data)
    ImVector<ImGui_ImplVulkanH_Frame>           Frames;
    ImVector<ImGui_ImplVulkanH_FrameSemaphores> FrameSemaphores;

    ImGui_ImplVulkanH_Window()
    {
        memset((void*)this, 0, sizeof(*this));
        PresentMode = (VkPresentModeKHR)~0;     // Ensure we get an error if user doesn't set this.
        ClearEnable = true;
    }
};

#endif // #ifndef IMGUI_DISABLE