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

// Missing features:
//  [ ] Renderer: User texture binding. Changes of ImTextureID aren't supported by this binding! See https://github.com/ocornut/imgui/pull/914

// You can copy and use unmodified imgui_impl_* files in your project. See main.cpp for an example of using this.
// If you are new to dear imgui, read examples/README.txt and read the documentation at the top of imgui.cpp.
// https://github.com/ocornut/imgui

// 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/

// CHANGELOG
// (minor and older changes stripped away, please see git history for details)
//  2018-11-30: Misc: Setting up io.BackendRendererName so it can be displayed in the About Window.
//  2018-08-25: Vulkan: Fixed mishandled VkSurfaceCapabilitiesKHR::maxImageCount=0 case.
//  2018-06-22: Inverted the parameters to ImGui_ImplVulkan_RenderDrawData() to be consistent with other bindings.
//  2018-06-08: Misc: Extracted imgui_impl_vulkan.cpp/.h away from the old combined GLFW+Vulkan example.
//  2018-06-08: Vulkan: Use draw_data->DisplayPos and draw_data->DisplaySize to setup projection matrix and clipping rectangle.
//  2018-03-03: Vulkan: Various refactor, created a couple of ImGui_ImplVulkanH_XXX helper that the example can use and that viewport support will use.
//  2018-03-01: Vulkan: Renamed ImGui_ImplVulkan_Init_Info to ImGui_ImplVulkan_InitInfo and fields to match more closely Vulkan terminology.
//  2018-02-16: Misc: Obsoleted the io.RenderDrawListsFn callback, ImGui_ImplVulkan_Render() calls ImGui_ImplVulkan_RenderDrawData() itself.
//  2018-02-06: Misc: Removed call to ImGui::Shutdown() which is not available from 1.60 WIP, user needs to call CreateContext/DestroyContext themselves.
//  2017-05-15: Vulkan: Fix scissor offset being negative. Fix new Vulkan validation warnings. Set required depth member for buffer image copy.
//  2016-11-13: Vulkan: Fix validation layer warnings and errors and redeclare gl_PerVertex.
//  2016-10-18: Vulkan: Add location decorators & change to use structs as in/out in glsl, update embedded spv (produced with glslangValidator -x). Null the released resources.
//  2016-08-27: Vulkan: Fix Vulkan example for use when a depth buffer is active.

#include "imgui.h"
#include "imgui_impl_vulkan.h"
#include <stdio.h>

// Vulkan data
static const VkAllocationCallbacks* g_Allocator = NULL;
static VkPhysicalDevice             g_PhysicalDevice = VK_NULL_HANDLE;
static VkInstance                   g_Instance = VK_NULL_HANDLE;
static VkDevice                     g_Device = VK_NULL_HANDLE;
static uint32_t                     g_QueueFamily = (uint32_t)-1;
static VkQueue                      g_Queue = VK_NULL_HANDLE;
static VkPipelineCache              g_PipelineCache = VK_NULL_HANDLE;
static VkDescriptorPool             g_DescriptorPool = VK_NULL_HANDLE;
static VkRenderPass                 g_RenderPass = VK_NULL_HANDLE;
static void                         (*g_CheckVkResultFn)(VkResult err) = NULL;

static VkDeviceSize                 g_BufferMemoryAlignment = 256;
static VkPipelineCreateFlags        g_PipelineCreateFlags = 0;

static VkDescriptorSetLayout        g_DescriptorSetLayout = VK_NULL_HANDLE;
static VkPipelineLayout             g_PipelineLayout = VK_NULL_HANDLE;
static VkDescriptorSet              g_DescriptorSet = VK_NULL_HANDLE;
static VkPipeline                   g_Pipeline = VK_NULL_HANDLE;

// Frame data
struct FrameDataForRender
{
    VkDeviceMemory  VertexBufferMemory;
    VkDeviceMemory  IndexBufferMemory;
    VkDeviceSize    VertexBufferSize;
    VkDeviceSize    IndexBufferSize;
    VkBuffer        VertexBuffer;
    VkBuffer        IndexBuffer;
};
static int                    g_FrameIndex = 0;
static FrameDataForRender     g_FramesDataBuffers[IMGUI_VK_QUEUED_FRAMES] = {};

// Font data
static VkSampler              g_FontSampler = VK_NULL_HANDLE;
static VkDeviceMemory         g_FontMemory = VK_NULL_HANDLE;
static VkImage                g_FontImage = VK_NULL_HANDLE;
static VkImageView            g_FontView = VK_NULL_HANDLE;
static VkDeviceMemory         g_UploadBufferMemory = VK_NULL_HANDLE;
static VkBuffer               g_UploadBuffer = VK_NULL_HANDLE;

// glsl_shader.vert, compiled with:
// # glslangValidator -V -x -o glsl_shader.vert.u32 glsl_shader.vert
static uint32_t __glsl_shader_vert_spv[] =
{
    0x07230203,0x00010000,0x00080001,0x0000002e,0x00000000,0x00020011,0x00000001,0x0006000b,
    0x00000001,0x4c534c47,0x6474732e,0x3035342e,0x00000000,0x0003000e,0x00000000,0x00000001,
    0x000a000f,0x00000000,0x00000004,0x6e69616d,0x00000000,0x0000000b,0x0000000f,0x00000015,
    0x0000001b,0x0000001c,0x00030003,0x00000002,0x000001c2,0x00040005,0x00000004,0x6e69616d,
    0x00000000,0x00030005,0x00000009,0x00000000,0x00050006,0x00000009,0x00000000,0x6f6c6f43,
    0x00000072,0x00040006,0x00000009,0x00000001,0x00005655,0x00030005,0x0000000b,0x0074754f,
    0x00040005,0x0000000f,0x6c6f4361,0x0000726f,0x00030005,0x00000015,0x00565561,0x00060005,
    0x00000019,0x505f6c67,0x65567265,0x78657472,0x00000000,0x00060006,0x00000019,0x00000000,
    0x505f6c67,0x7469736f,0x006e6f69,0x00030005,0x0000001b,0x00000000,0x00040005,0x0000001c,
    0x736f5061,0x00000000,0x00060005,0x0000001e,0x73755075,0x6e6f4368,0x6e617473,0x00000074,
    0x00050006,0x0000001e,0x00000000,0x61635375,0x0000656c,0x00060006,0x0000001e,0x00000001,
    0x61725475,0x616c736e,0x00006574,0x00030005,0x00000020,0x00006370,0x00040047,0x0000000b,
    0x0000001e,0x00000000,0x00040047,0x0000000f,0x0000001e,0x00000002,0x00040047,0x00000015,
    0x0000001e,0x00000001,0x00050048,0x00000019,0x00000000,0x0000000b,0x00000000,0x00030047,
    0x00000019,0x00000002,0x00040047,0x0000001c,0x0000001e,0x00000000,0x00050048,0x0000001e,
    0x00000000,0x00000023,0x00000000,0x00050048,0x0000001e,0x00000001,0x00000023,0x00000008,
    0x00030047,0x0000001e,0x00000002,0x00020013,0x00000002,0x00030021,0x00000003,0x00000002,
    0x00030016,0x00000006,0x00000020,0x00040017,0x00000007,0x00000006,0x00000004,0x00040017,
    0x00000008,0x00000006,0x00000002,0x0004001e,0x00000009,0x00000007,0x00000008,0x00040020,
    0x0000000a,0x00000003,0x00000009,0x0004003b,0x0000000a,0x0000000b,0x00000003,0x00040015,
    0x0000000c,0x00000020,0x00000001,0x0004002b,0x0000000c,0x0000000d,0x00000000,0x00040020,
    0x0000000e,0x00000001,0x00000007,0x0004003b,0x0000000e,0x0000000f,0x00000001,0x00040020,
    0x00000011,0x00000003,0x00000007,0x0004002b,0x0000000c,0x00000013,0x00000001,0x00040020,
    0x00000014,0x00000001,0x00000008,0x0004003b,0x00000014,0x00000015,0x00000001,0x00040020,
    0x00000017,0x00000003,0x00000008,0x0003001e,0x00000019,0x00000007,0x00040020,0x0000001a,
    0x00000003,0x00000019,0x0004003b,0x0000001a,0x0000001b,0x00000003,0x0004003b,0x00000014,
    0x0000001c,0x00000001,0x0004001e,0x0000001e,0x00000008,0x00000008,0x00040020,0x0000001f,
    0x00000009,0x0000001e,0x0004003b,0x0000001f,0x00000020,0x00000009,0x00040020,0x00000021,
    0x00000009,0x00000008,0x0004002b,0x00000006,0x00000028,0x00000000,0x0004002b,0x00000006,
    0x00000029,0x3f800000,0x00050036,0x00000002,0x00000004,0x00000000,0x00000003,0x000200f8,
    0x00000005,0x0004003d,0x00000007,0x00000010,0x0000000f,0x00050041,0x00000011,0x00000012,
    0x0000000b,0x0000000d,0x0003003e,0x00000012,0x00000010,0x0004003d,0x00000008,0x00000016,
    0x00000015,0x00050041,0x00000017,0x00000018,0x0000000b,0x00000013,0x0003003e,0x00000018,
    0x00000016,0x0004003d,0x00000008,0x0000001d,0x0000001c,0x00050041,0x00000021,0x00000022,
    0x00000020,0x0000000d,0x0004003d,0x00000008,0x00000023,0x00000022,0x00050085,0x00000008,
    0x00000024,0x0000001d,0x00000023,0x00050041,0x00000021,0x00000025,0x00000020,0x00000013,
    0x0004003d,0x00000008,0x00000026,0x00000025,0x00050081,0x00000008,0x00000027,0x00000024,
    0x00000026,0x00050051,0x00000006,0x0000002a,0x00000027,0x00000000,0x00050051,0x00000006,
    0x0000002b,0x00000027,0x00000001,0x00070050,0x00000007,0x0000002c,0x0000002a,0x0000002b,
    0x00000028,0x00000029,0x00050041,0x00000011,0x0000002d,0x0000001b,0x0000000d,0x0003003e,
    0x0000002d,0x0000002c,0x000100fd,0x00010038
};

// glsl_shader.frag, compiled with:
// # glslangValidator -V -x -o glsl_shader.frag.u32 glsl_shader.frag
static uint32_t __glsl_shader_frag_spv[] =
{
    0x07230203,0x00010000,0x00080001,0x0000001e,0x00000000,0x00020011,0x00000001,0x0006000b,
    0x00000001,0x4c534c47,0x6474732e,0x3035342e,0x00000000,0x0003000e,0x00000000,0x00000001,
    0x0007000f,0x00000004,0x00000004,0x6e69616d,0x00000000,0x00000009,0x0000000d,0x00030010,
    0x00000004,0x00000007,0x00030003,0x00000002,0x000001c2,0x00040005,0x00000004,0x6e69616d,
    0x00000000,0x00040005,0x00000009,0x6c6f4366,0x0000726f,0x00030005,0x0000000b,0x00000000,
    0x00050006,0x0000000b,0x00000000,0x6f6c6f43,0x00000072,0x00040006,0x0000000b,0x00000001,
    0x00005655,0x00030005,0x0000000d,0x00006e49,0x00050005,0x00000016,0x78655473,0x65727574,
    0x00000000,0x00040047,0x00000009,0x0000001e,0x00000000,0x00040047,0x0000000d,0x0000001e,
    0x00000000,0x00040047,0x00000016,0x00000022,0x00000000,0x00040047,0x00000016,0x00000021,
    0x00000000,0x00020013,0x00000002,0x00030021,0x00000003,0x00000002,0x00030016,0x00000006,
    0x00000020,0x00040017,0x00000007,0x00000006,0x00000004,0x00040020,0x00000008,0x00000003,
    0x00000007,0x0004003b,0x00000008,0x00000009,0x00000003,0x00040017,0x0000000a,0x00000006,
    0x00000002,0x0004001e,0x0000000b,0x00000007,0x0000000a,0x00040020,0x0000000c,0x00000001,
    0x0000000b,0x0004003b,0x0000000c,0x0000000d,0x00000001,0x00040015,0x0000000e,0x00000020,
    0x00000001,0x0004002b,0x0000000e,0x0000000f,0x00000000,0x00040020,0x00000010,0x00000001,
    0x00000007,0x00090019,0x00000013,0x00000006,0x00000001,0x00000000,0x00000000,0x00000000,
    0x00000001,0x00000000,0x0003001b,0x00000014,0x00000013,0x00040020,0x00000015,0x00000000,
    0x00000014,0x0004003b,0x00000015,0x00000016,0x00000000,0x0004002b,0x0000000e,0x00000018,
    0x00000001,0x00040020,0x00000019,0x00000001,0x0000000a,0x00050036,0x00000002,0x00000004,
    0x00000000,0x00000003,0x000200f8,0x00000005,0x00050041,0x00000010,0x00000011,0x0000000d,
    0x0000000f,0x0004003d,0x00000007,0x00000012,0x00000011,0x0004003d,0x00000014,0x00000017,
    0x00000016,0x00050041,0x00000019,0x0000001a,0x0000000d,0x00000018,0x0004003d,0x0000000a,
    0x0000001b,0x0000001a,0x00050057,0x00000007,0x0000001c,0x00000017,0x0000001b,0x00050085,
    0x00000007,0x0000001d,0x00000012,0x0000001c,0x0003003e,0x00000009,0x0000001d,0x000100fd,
    0x00010038
};

static uint32_t ImGui_ImplVulkan_MemoryType(VkMemoryPropertyFlags properties, uint32_t type_bits)
{
    VkPhysicalDeviceMemoryProperties prop;
    vkGetPhysicalDeviceMemoryProperties(g_PhysicalDevice, &prop);
    for (uint32_t i = 0; i < prop.memoryTypeCount; i++)
        if ((prop.memoryTypes[i].propertyFlags & properties) == properties && type_bits & (1<<i))
            return i;
    return 0xFFFFFFFF; // Unable to find memoryType
}

static void check_vk_result(VkResult err)
{
    if (g_CheckVkResultFn)
        g_CheckVkResultFn(err);
}

static void CreateOrResizeBuffer(VkBuffer& buffer, VkDeviceMemory& buffer_memory, VkDeviceSize& p_buffer_size, size_t new_size, VkBufferUsageFlagBits usage)
{
    VkResult err;
    if (buffer != VK_NULL_HANDLE)
        vkDestroyBuffer(g_Device, buffer, g_Allocator);
    if (buffer_memory)
        vkFreeMemory(g_Device, buffer_memory, g_Allocator);

    VkDeviceSize vertex_buffer_size_aligned = ((new_size - 1) / g_BufferMemoryAlignment + 1) * g_BufferMemoryAlignment;
    VkBufferCreateInfo buffer_info = {};
    buffer_info.sType = VK_STRUCTURE_TYPE_BUFFER_CREATE_INFO;
    buffer_info.size = vertex_buffer_size_aligned;
    buffer_info.usage = usage;
    buffer_info.sharingMode = VK_SHARING_MODE_EXCLUSIVE;
    err = vkCreateBuffer(g_Device, &buffer_info, g_Allocator, &buffer);
    check_vk_result(err);

    VkMemoryRequirements req;
    vkGetBufferMemoryRequirements(g_Device, buffer, &req);
    g_BufferMemoryAlignment = (g_BufferMemoryAlignment > req.alignment) ? g_BufferMemoryAlignment : req.alignment;
    VkMemoryAllocateInfo alloc_info = {};
    alloc_info.sType = VK_STRUCTURE_TYPE_MEMORY_ALLOCATE_INFO;
    alloc_info.allocationSize = req.size;
    alloc_info.memoryTypeIndex = ImGui_ImplVulkan_MemoryType(VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT, req.memoryTypeBits);
    err = vkAllocateMemory(g_Device, &alloc_info, g_Allocator, &buffer_memory);
    check_vk_result(err);

    err = vkBindBufferMemory(g_Device, buffer, buffer_memory, 0);
    check_vk_result(err);
    p_buffer_size = new_size;
}

// Render function
// (this used to be set in io.RenderDrawListsFn and called by ImGui::Render(), but you can now call this directly from your main loop)
void ImGui_ImplVulkan_RenderDrawData(ImDrawData* draw_data, VkCommandBuffer command_buffer)
{
    VkResult err;
    if (draw_data->TotalVtxCount == 0)
        return;

    FrameDataForRender* fd = &g_FramesDataBuffers[g_FrameIndex];
    g_FrameIndex = (g_FrameIndex + 1) % IMGUI_VK_QUEUED_FRAMES;

    // Create the Vertex and Index buffers:
    size_t vertex_size = draw_data->TotalVtxCount * sizeof(ImDrawVert);
    size_t index_size = draw_data->TotalIdxCount * sizeof(ImDrawIdx);
    if (!fd->VertexBuffer || fd->VertexBufferSize < vertex_size)
        CreateOrResizeBuffer(fd->VertexBuffer, fd->VertexBufferMemory, fd->VertexBufferSize, vertex_size, VK_BUFFER_USAGE_VERTEX_BUFFER_BIT);
    if (!fd->IndexBuffer || fd->IndexBufferSize < index_size)
        CreateOrResizeBuffer(fd->IndexBuffer, fd->IndexBufferMemory, fd->IndexBufferSize, index_size, VK_BUFFER_USAGE_INDEX_BUFFER_BIT);

    // Upload Vertex and index Data:
    {
        ImDrawVert* vtx_dst = NULL;
        ImDrawIdx* idx_dst = NULL;
        err = vkMapMemory(g_Device, fd->VertexBufferMemory, 0, vertex_size, 0, (void**)(&vtx_dst));
        check_vk_result(err);
        err = vkMapMemory(g_Device, fd->IndexBufferMemory, 0, index_size, 0, (void**)(&idx_dst));
        check_vk_result(err);
        for (int n = 0; n < draw_data->CmdListsCount; n++)
        {
            const ImDrawList* cmd_list = draw_data->CmdLists[n];
            memcpy(vtx_dst, cmd_list->VtxBuffer.Data, cmd_list->VtxBuffer.Size * sizeof(ImDrawVert));
            memcpy(idx_dst, cmd_list->IdxBuffer.Data, cmd_list->IdxBuffer.Size * sizeof(ImDrawIdx));
            vtx_dst += cmd_list->VtxBuffer.Size;
            idx_dst += cmd_list->IdxBuffer.Size;
        }
        VkMappedMemoryRange range[2] = {};
        range[0].sType = VK_STRUCTURE_TYPE_MAPPED_MEMORY_RANGE;
        range[0].memory = fd->VertexBufferMemory;
        range[0].size = VK_WHOLE_SIZE;
        range[1].sType = VK_STRUCTURE_TYPE_MAPPED_MEMORY_RANGE;
        range[1].memory = fd->IndexBufferMemory;
        range[1].size = VK_WHOLE_SIZE;
        err = vkFlushMappedMemoryRanges(g_Device, 2, range);
        check_vk_result(err);
        vkUnmapMemory(g_Device, fd->VertexBufferMemory);
        vkUnmapMemory(g_Device, fd->IndexBufferMemory);
    }

    // Bind pipeline and descriptor sets:
    {
        vkCmdBindPipeline(command_buffer, VK_PIPELINE_BIND_POINT_GRAPHICS, g_Pipeline);
        VkDescriptorSet desc_set[1] = { g_DescriptorSet };
        vkCmdBindDescriptorSets(command_buffer, VK_PIPELINE_BIND_POINT_GRAPHICS, g_PipelineLayout, 0, 1, desc_set, 0, NULL);
    }

    // Bind Vertex And Index Buffer:
    {
        VkBuffer vertex_buffers[1] = { fd->VertexBuffer };
        VkDeviceSize vertex_offset[1] = { 0 };
        vkCmdBindVertexBuffers(command_buffer, 0, 1, vertex_buffers, vertex_offset);
        vkCmdBindIndexBuffer(command_buffer, fd->IndexBuffer, 0, VK_INDEX_TYPE_UINT16);
    }

    // Setup viewport:
    {
        VkViewport viewport;
        viewport.x = 0;
        viewport.y = 0;
        viewport.width = draw_data->DisplaySize.x;
        viewport.height = draw_data->DisplaySize.y;
        viewport.minDepth = 0.0f;
        viewport.maxDepth = 1.0f;
        vkCmdSetViewport(command_buffer, 0, 1, &viewport);
    }

    // Setup scale and translation:
    // Our visible imgui space lies from draw_data->DisplayPos (top left) to draw_data->DisplayPos+data_data->DisplaySize (bottom right). DisplayMin is typically (0,0) for single viewport apps.
    {
        float scale[2];
        scale[0] = 2.0f / draw_data->DisplaySize.x;
        scale[1] = 2.0f / draw_data->DisplaySize.y;
        float translate[2];
        translate[0] = -1.0f - draw_data->DisplayPos.x * scale[0];
        translate[1] = -1.0f - draw_data->DisplayPos.y * scale[1];
        vkCmdPushConstants(command_buffer, g_PipelineLayout, VK_SHADER_STAGE_VERTEX_BIT, sizeof(float) * 0, sizeof(float) * 2, scale);
        vkCmdPushConstants(command_buffer, g_PipelineLayout, VK_SHADER_STAGE_VERTEX_BIT, sizeof(float) * 2, sizeof(float) * 2, translate);
    }

    // Render the command lists:
    int vtx_offset = 0;
    int idx_offset = 0;
    ImVec2 display_pos = draw_data->DisplayPos;
    for (int n = 0; n < draw_data->CmdListsCount; n++)
    {
        const ImDrawList* cmd_list = draw_data->CmdLists[n];
        for (int cmd_i = 0; cmd_i < cmd_list->CmdBuffer.Size; cmd_i++)
        {
            const ImDrawCmd* pcmd = &cmd_list->CmdBuffer[cmd_i];
            if (pcmd->UserCallback)
            {
                pcmd->UserCallback(cmd_list, pcmd);
            }
            else
            {
                // Apply scissor/clipping rectangle
                // FIXME: We could clamp width/height based on clamped min/max values.
                VkRect2D scissor;
                scissor.offset.x = (int32_t)(pcmd->ClipRect.x - display_pos.x) > 0 ? (int32_t)(pcmd->ClipRect.x - display_pos.x) : 0;
                scissor.offset.y = (int32_t)(pcmd->ClipRect.y - display_pos.y) > 0 ? (int32_t)(pcmd->ClipRect.y - display_pos.y) : 0;
                scissor.extent.width = (uint32_t)(pcmd->ClipRect.z - pcmd->ClipRect.x);
                scissor.extent.height = (uint32_t)(pcmd->ClipRect.w - pcmd->ClipRect.y + 1); // FIXME: Why +1 here?
                vkCmdSetScissor(command_buffer, 0, 1, &scissor);
                
                // Draw
                vkCmdDrawIndexed(command_buffer, pcmd->ElemCount, 1, idx_offset, vtx_offset, 0);
            }
            idx_offset += pcmd->ElemCount;
        }
        vtx_offset += cmd_list->VtxBuffer.Size;
    }
}

bool ImGui_ImplVulkan_CreateFontsTexture(VkCommandBuffer command_buffer)
{
    ImGuiIO& io = ImGui::GetIO();

    unsigned char* pixels;
    int width, height;
    io.Fonts->GetTexDataAsRGBA32(&pixels, &width, &height);
    size_t upload_size = width*height*4*sizeof(char);

    VkResult err;

    // Create the Image:
    {
        VkImageCreateInfo info = {};
        info.sType = VK_STRUCTURE_TYPE_IMAGE_CREATE_INFO;
        info.imageType = VK_IMAGE_TYPE_2D;
        info.format = VK_FORMAT_R8G8B8A8_UNORM;
        info.extent.width = width;
        info.extent.height = height;
        info.extent.depth = 1;
        info.mipLevels = 1;
        info.arrayLayers = 1;
        info.samples = VK_SAMPLE_COUNT_1_BIT;
        info.tiling = VK_IMAGE_TILING_OPTIMAL;
        info.usage = VK_IMAGE_USAGE_SAMPLED_BIT | VK_IMAGE_USAGE_TRANSFER_DST_BIT;
        info.sharingMode = VK_SHARING_MODE_EXCLUSIVE;
        info.initialLayout = VK_IMAGE_LAYOUT_UNDEFINED;
        err = vkCreateImage(g_Device, &info, g_Allocator, &g_FontImage);
        check_vk_result(err);
        VkMemoryRequirements req;
        vkGetImageMemoryRequirements(g_Device, g_FontImage, &req);
        VkMemoryAllocateInfo alloc_info = {};
        alloc_info.sType = VK_STRUCTURE_TYPE_MEMORY_ALLOCATE_INFO;
        alloc_info.allocationSize = req.size;
        alloc_info.memoryTypeIndex = ImGui_ImplVulkan_MemoryType(VK_MEMORY_PROPERTY_DEVICE_LOCAL_BIT, req.memoryTypeBits);
        err = vkAllocateMemory(g_Device, &alloc_info, g_Allocator, &g_FontMemory);
        check_vk_result(err);
        err = vkBindImageMemory(g_Device, g_FontImage, g_FontMemory, 0);
        check_vk_result(err);
    }

    // Create the Image View:
    {
        VkImageViewCreateInfo info = {};
        info.sType = VK_STRUCTURE_TYPE_IMAGE_VIEW_CREATE_INFO;
        info.image = g_FontImage;
        info.viewType = VK_IMAGE_VIEW_TYPE_2D;
        info.format = VK_FORMAT_R8G8B8A8_UNORM;
        info.subresourceRange.aspectMask = VK_IMAGE_ASPECT_COLOR_BIT;
        info.subresourceRange.levelCount = 1;
        info.subresourceRange.layerCount = 1;
        err = vkCreateImageView(g_Device, &info, g_Allocator, &g_FontView);
        check_vk_result(err);
    }

    // Update the Descriptor Set:
    {
        VkDescriptorImageInfo desc_image[1] = {};
        desc_image[0].sampler = g_FontSampler;
        desc_image[0].imageView = g_FontView;
        desc_image[0].imageLayout = VK_IMAGE_LAYOUT_SHADER_READ_ONLY_OPTIMAL;
        VkWriteDescriptorSet write_desc[1] = {};
        write_desc[0].sType = VK_STRUCTURE_TYPE_WRITE_DESCRIPTOR_SET;
        write_desc[0].dstSet = g_DescriptorSet;
        write_desc[0].descriptorCount = 1;
        write_desc[0].descriptorType = VK_DESCRIPTOR_TYPE_COMBINED_IMAGE_SAMPLER;
        write_desc[0].pImageInfo = desc_image;
        vkUpdateDescriptorSets(g_Device, 1, write_desc, 0, NULL);
    }

    // Create the Upload Buffer:
    {
        VkBufferCreateInfo buffer_info = {};
        buffer_info.sType = VK_STRUCTURE_TYPE_BUFFER_CREATE_INFO;
        buffer_info.size = upload_size;
        buffer_info.usage = VK_BUFFER_USAGE_TRANSFER_SRC_BIT;
        buffer_info.sharingMode = VK_SHARING_MODE_EXCLUSIVE;
        err = vkCreateBuffer(g_Device, &buffer_info, g_Allocator, &g_UploadBuffer);
        check_vk_result(err);
        VkMemoryRequirements req;
        vkGetBufferMemoryRequirements(g_Device, g_UploadBuffer, &req);
        g_BufferMemoryAlignment = (g_BufferMemoryAlignment > req.alignment) ? g_BufferMemoryAlignment : req.alignment;
        VkMemoryAllocateInfo alloc_info = {};
        alloc_info.sType = VK_STRUCTURE_TYPE_MEMORY_ALLOCATE_INFO;
        alloc_info.allocationSize = req.size;
        alloc_info.memoryTypeIndex = ImGui_ImplVulkan_MemoryType(VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT, req.memoryTypeBits);
        err = vkAllocateMemory(g_Device, &alloc_info, g_Allocator, &g_UploadBufferMemory);
        check_vk_result(err);
        err = vkBindBufferMemory(g_Device, g_UploadBuffer, g_UploadBufferMemory, 0);
        check_vk_result(err);
    }

    // Upload to Buffer:
    {
        char* map = NULL;
        err = vkMapMemory(g_Device, g_UploadBufferMemory, 0, upload_size, 0, (void**)(&map));
        check_vk_result(err);
        memcpy(map, pixels, upload_size);
        VkMappedMemoryRange range[1] = {};
        range[0].sType = VK_STRUCTURE_TYPE_MAPPED_MEMORY_RANGE;
        range[0].memory = g_UploadBufferMemory;
        range[0].size = upload_size;
        err = vkFlushMappedMemoryRanges(g_Device, 1, range);
        check_vk_result(err);
        vkUnmapMemory(g_Device, g_UploadBufferMemory);
    }

    // Copy to Image:
    {
        VkImageMemoryBarrier copy_barrier[1] = {};
        copy_barrier[0].sType = VK_STRUCTURE_TYPE_IMAGE_MEMORY_BARRIER;
        copy_barrier[0].dstAccessMask = VK_ACCESS_TRANSFER_WRITE_BIT;
        copy_barrier[0].oldLayout = VK_IMAGE_LAYOUT_UNDEFINED;
        copy_barrier[0].newLayout = VK_IMAGE_LAYOUT_TRANSFER_DST_OPTIMAL;
        copy_barrier[0].srcQueueFamilyIndex = VK_QUEUE_FAMILY_IGNORED;
        copy_barrier[0].dstQueueFamilyIndex = VK_QUEUE_FAMILY_IGNORED;
        copy_barrier[0].image = g_FontImage;
        copy_barrier[0].subresourceRange.aspectMask = VK_IMAGE_ASPECT_COLOR_BIT;
        copy_barrier[0].subresourceRange.levelCount = 1;
        copy_barrier[0].subresourceRange.layerCount = 1;
        vkCmdPipelineBarrier(command_buffer, VK_PIPELINE_STAGE_HOST_BIT, VK_PIPELINE_STAGE_TRANSFER_BIT, 0, 0, NULL, 0, NULL, 1, copy_barrier);

        VkBufferImageCopy region = {};
        region.imageSubresource.aspectMask = VK_IMAGE_ASPECT_COLOR_BIT;
        region.imageSubresource.layerCount = 1;
        region.imageExtent.width = width;
        region.imageExtent.height = height;
        region.imageExtent.depth = 1;
        vkCmdCopyBufferToImage(command_buffer, g_UploadBuffer, g_FontImage, VK_IMAGE_LAYOUT_TRANSFER_DST_OPTIMAL, 1, &region);

        VkImageMemoryBarrier use_barrier[1] = {};
        use_barrier[0].sType = VK_STRUCTURE_TYPE_IMAGE_MEMORY_BARRIER;
        use_barrier[0].srcAccessMask = VK_ACCESS_TRANSFER_WRITE_BIT;
        use_barrier[0].dstAccessMask = VK_ACCESS_SHADER_READ_BIT;
        use_barrier[0].oldLayout = VK_IMAGE_LAYOUT_TRANSFER_DST_OPTIMAL;
        use_barrier[0].newLayout = VK_IMAGE_LAYOUT_SHADER_READ_ONLY_OPTIMAL;
        use_barrier[0].srcQueueFamilyIndex = VK_QUEUE_FAMILY_IGNORED;
        use_barrier[0].dstQueueFamilyIndex = VK_QUEUE_FAMILY_IGNORED;
        use_barrier[0].image = g_FontImage;
        use_barrier[0].subresourceRange.aspectMask = VK_IMAGE_ASPECT_COLOR_BIT;
        use_barrier[0].subresourceRange.levelCount = 1;
        use_barrier[0].subresourceRange.layerCount = 1;
        vkCmdPipelineBarrier(command_buffer, VK_PIPELINE_STAGE_TRANSFER_BIT, VK_PIPELINE_STAGE_FRAGMENT_SHADER_BIT, 0, 0, NULL, 0, NULL, 1, use_barrier);
    }

    // Store our identifier
    io.Fonts->TexID = (ImTextureID)(intptr_t)g_FontImage;

    return true;
}

bool ImGui_ImplVulkan_CreateDeviceObjects()
{
    VkResult err;
    VkShaderModule vert_module;
    VkShaderModule frag_module;

    // Create The Shader Modules:
    {
        VkShaderModuleCreateInfo vert_info = {};
        vert_info.sType = VK_STRUCTURE_TYPE_SHADER_MODULE_CREATE_INFO;
        vert_info.codeSize = sizeof(__glsl_shader_vert_spv);
        vert_info.pCode = (uint32_t*)__glsl_shader_vert_spv;
        err = vkCreateShaderModule(g_Device, &vert_info, g_Allocator, &vert_module);
        check_vk_result(err);
        VkShaderModuleCreateInfo frag_info = {};
        frag_info.sType = VK_STRUCTURE_TYPE_SHADER_MODULE_CREATE_INFO;
        frag_info.codeSize = sizeof(__glsl_shader_frag_spv);
        frag_info.pCode = (uint32_t*)__glsl_shader_frag_spv;
        err = vkCreateShaderModule(g_Device, &frag_info, g_Allocator, &frag_module);
        check_vk_result(err);
    }

    if (!g_FontSampler)
    {
        VkSamplerCreateInfo info = {};
        info.sType = VK_STRUCTURE_TYPE_SAMPLER_CREATE_INFO;
        info.magFilter = VK_FILTER_LINEAR;
        info.minFilter = VK_FILTER_LINEAR;
        info.mipmapMode = VK_SAMPLER_MIPMAP_MODE_LINEAR;
        info.addressModeU = VK_SAMPLER_ADDRESS_MODE_REPEAT;
        info.addressModeV = VK_SAMPLER_ADDRESS_MODE_REPEAT;
        info.addressModeW = VK_SAMPLER_ADDRESS_MODE_REPEAT;
        info.minLod = -1000;
        info.maxLod = 1000;
        info.maxAnisotropy = 1.0f;
        err = vkCreateSampler(g_Device, &info, g_Allocator, &g_FontSampler);
        check_vk_result(err);
    }

    if (!g_DescriptorSetLayout)
    {
        VkSampler sampler[1] = {g_FontSampler};
        VkDescriptorSetLayoutBinding binding[1] = {};
        binding[0].descriptorType = VK_DESCRIPTOR_TYPE_COMBINED_IMAGE_SAMPLER;
        binding[0].descriptorCount = 1;
        binding[0].stageFlags = VK_SHADER_STAGE_FRAGMENT_BIT;
        binding[0].pImmutableSamplers = sampler;
        VkDescriptorSetLayoutCreateInfo info = {};
        info.sType = VK_STRUCTURE_TYPE_DESCRIPTOR_SET_LAYOUT_CREATE_INFO;
        info.bindingCount = 1;
        info.pBindings = binding;
        err = vkCreateDescriptorSetLayout(g_Device, &info, g_Allocator, &g_DescriptorSetLayout);
        check_vk_result(err);
    }

    // Create Descriptor Set:
    {
        VkDescriptorSetAllocateInfo alloc_info = {};
        alloc_info.sType = VK_STRUCTURE_TYPE_DESCRIPTOR_SET_ALLOCATE_INFO;
        alloc_info.descriptorPool = g_DescriptorPool;
        alloc_info.descriptorSetCount = 1;
        alloc_info.pSetLayouts = &g_DescriptorSetLayout;
        err = vkAllocateDescriptorSets(g_Device, &alloc_info, &g_DescriptorSet);
        check_vk_result(err);
    }

    if (!g_PipelineLayout)
    {
        // Constants: we are using 'vec2 offset' and 'vec2 scale' instead of a full 3d projection matrix
        VkPushConstantRange push_constants[1] = {};
        push_constants[0].stageFlags = VK_SHADER_STAGE_VERTEX_BIT;
        push_constants[0].offset = sizeof(float) * 0;
        push_constants[0].size = sizeof(float) * 4;
        VkDescriptorSetLayout set_layout[1] = { g_DescriptorSetLayout };
        VkPipelineLayoutCreateInfo layout_info = {};
        layout_info.sType = VK_STRUCTURE_TYPE_PIPELINE_LAYOUT_CREATE_INFO;
        layout_info.setLayoutCount = 1;
        layout_info.pSetLayouts = set_layout;
        layout_info.pushConstantRangeCount = 1;
        layout_info.pPushConstantRanges = push_constants;
        err = vkCreatePipelineLayout(g_Device, &layout_info, g_Allocator, &g_PipelineLayout);
        check_vk_result(err);
    }

    VkPipelineShaderStageCreateInfo stage[2] = {};
    stage[0].sType = VK_STRUCTURE_TYPE_PIPELINE_SHADER_STAGE_CREATE_INFO;
    stage[0].stage = VK_SHADER_STAGE_VERTEX_BIT;
    stage[0].module = vert_module;
    stage[0].pName = "main";
    stage[1].sType = VK_STRUCTURE_TYPE_PIPELINE_SHADER_STAGE_CREATE_INFO;
    stage[1].stage = VK_SHADER_STAGE_FRAGMENT_BIT;
    stage[1].module = frag_module;
    stage[1].pName = "main";

    VkVertexInputBindingDescription binding_desc[1] = {};
    binding_desc[0].stride = sizeof(ImDrawVert);
    binding_desc[0].inputRate = VK_VERTEX_INPUT_RATE_VERTEX;

    VkVertexInputAttributeDescription attribute_desc[3] = {};
    attribute_desc[0].location = 0;
    attribute_desc[0].binding = binding_desc[0].binding;
    attribute_desc[0].format = VK_FORMAT_R32G32_SFLOAT;
    attribute_desc[0].offset = IM_OFFSETOF(ImDrawVert, pos);
    attribute_desc[1].location = 1;
    attribute_desc[1].binding = binding_desc[0].binding;
    attribute_desc[1].format = VK_FORMAT_R32G32_SFLOAT;
    attribute_desc[1].offset = IM_OFFSETOF(ImDrawVert, uv);
    attribute_desc[2].location = 2;
    attribute_desc[2].binding = binding_desc[0].binding;
    attribute_desc[2].format = VK_FORMAT_R8G8B8A8_UNORM;
    attribute_desc[2].offset = IM_OFFSETOF(ImDrawVert, col);

    VkPipelineVertexInputStateCreateInfo vertex_info = {};
    vertex_info.sType = VK_STRUCTURE_TYPE_PIPELINE_VERTEX_INPUT_STATE_CREATE_INFO;
    vertex_info.vertexBindingDescriptionCount = 1;
    vertex_info.pVertexBindingDescriptions = binding_desc;
    vertex_info.vertexAttributeDescriptionCount = 3;
    vertex_info.pVertexAttributeDescriptions = attribute_desc;

    VkPipelineInputAssemblyStateCreateInfo ia_info = {};
    ia_info.sType = VK_STRUCTURE_TYPE_PIPELINE_INPUT_ASSEMBLY_STATE_CREATE_INFO;
    ia_info.topology = VK_PRIMITIVE_TOPOLOGY_TRIANGLE_LIST;

    VkPipelineViewportStateCreateInfo viewport_info = {};
    viewport_info.sType = VK_STRUCTURE_TYPE_PIPELINE_VIEWPORT_STATE_CREATE_INFO;
    viewport_info.viewportCount = 1;
    viewport_info.scissorCount = 1;

    VkPipelineRasterizationStateCreateInfo raster_info = {};
    raster_info.sType = VK_STRUCTURE_TYPE_PIPELINE_RASTERIZATION_STATE_CREATE_INFO;
    raster_info.polygonMode = VK_POLYGON_MODE_FILL;
    raster_info.cullMode = VK_CULL_MODE_NONE;
    raster_info.frontFace = VK_FRONT_FACE_COUNTER_CLOCKWISE;
    raster_info.lineWidth = 1.0f;

    VkPipelineMultisampleStateCreateInfo ms_info = {};
    ms_info.sType = VK_STRUCTURE_TYPE_PIPELINE_MULTISAMPLE_STATE_CREATE_INFO;
    ms_info.rasterizationSamples = VK_SAMPLE_COUNT_1_BIT;

    VkPipelineColorBlendAttachmentState color_attachment[1] = {};
    color_attachment[0].blendEnable = VK_TRUE;
    color_attachment[0].srcColorBlendFactor = VK_BLEND_FACTOR_SRC_ALPHA;
    color_attachment[0].dstColorBlendFactor = VK_BLEND_FACTOR_ONE_MINUS_SRC_ALPHA;
    color_attachment[0].colorBlendOp = VK_BLEND_OP_ADD;
    color_attachment[0].srcAlphaBlendFactor = VK_BLEND_FACTOR_ONE_MINUS_SRC_ALPHA;
    color_attachment[0].dstAlphaBlendFactor = VK_BLEND_FACTOR_ZERO;
    color_attachment[0].alphaBlendOp = VK_BLEND_OP_ADD;
    color_attachment[0].colorWriteMask = VK_COLOR_COMPONENT_R_BIT | VK_COLOR_COMPONENT_G_BIT | VK_COLOR_COMPONENT_B_BIT | VK_COLOR_COMPONENT_A_BIT;

    VkPipelineDepthStencilStateCreateInfo depth_info = {};
    depth_info.sType = VK_STRUCTURE_TYPE_PIPELINE_DEPTH_STENCIL_STATE_CREATE_INFO;

    VkPipelineColorBlendStateCreateInfo blend_info = {};
    blend_info.sType = VK_STRUCTURE_TYPE_PIPELINE_COLOR_BLEND_STATE_CREATE_INFO;
    blend_info.attachmentCount = 1;
    blend_info.pAttachments = color_attachment;

    VkDynamicState dynamic_states[2] = { VK_DYNAMIC_STATE_VIEWPORT, VK_DYNAMIC_STATE_SCISSOR };
    VkPipelineDynamicStateCreateInfo dynamic_state = {};
    dynamic_state.sType = VK_STRUCTURE_TYPE_PIPELINE_DYNAMIC_STATE_CREATE_INFO;
    dynamic_state.dynamicStateCount = (uint32_t)IM_ARRAYSIZE(dynamic_states);
    dynamic_state.pDynamicStates = dynamic_states;

    VkGraphicsPipelineCreateInfo info = {};
    info.sType = VK_STRUCTURE_TYPE_GRAPHICS_PIPELINE_CREATE_INFO;
    info.flags = g_PipelineCreateFlags;
    info.stageCount = 2;
    info.pStages = stage;
    info.pVertexInputState = &vertex_info;
    info.pInputAssemblyState = &ia_info;
    info.pViewportState = &viewport_info;
    info.pRasterizationState = &raster_info;
    info.pMultisampleState = &ms_info;
    info.pDepthStencilState = &depth_info;
    info.pColorBlendState = &blend_info;
    info.pDynamicState = &dynamic_state;
    info.layout = g_PipelineLayout;
    info.renderPass = g_RenderPass;
    err = vkCreateGraphicsPipelines(g_Device, g_PipelineCache, 1, &info, g_Allocator, &g_Pipeline);
    check_vk_result(err);

    vkDestroyShaderModule(g_Device, vert_module, g_Allocator);
    vkDestroyShaderModule(g_Device, frag_module, g_Allocator);

    return true;
}

void    ImGui_ImplVulkan_InvalidateFontUploadObjects()
{
    if (g_UploadBuffer)
    {
        vkDestroyBuffer(g_Device, g_UploadBuffer, g_Allocator);
        g_UploadBuffer = VK_NULL_HANDLE;
    }
    if (g_UploadBufferMemory)
    {
        vkFreeMemory(g_Device, g_UploadBufferMemory, g_Allocator);
        g_UploadBufferMemory = VK_NULL_HANDLE;
    }
}

void    ImGui_ImplVulkan_InvalidateDeviceObjects()
{
    ImGui_ImplVulkan_InvalidateFontUploadObjects();

    for (int i = 0; i < IMGUI_VK_QUEUED_FRAMES; i++)
    {
        FrameDataForRender* fd = &g_FramesDataBuffers[i];
        if (fd->VertexBuffer)       { vkDestroyBuffer   (g_Device, fd->VertexBuffer,        g_Allocator); fd->VertexBuffer = VK_NULL_HANDLE; }
        if (fd->VertexBufferMemory) { vkFreeMemory      (g_Device, fd->VertexBufferMemory,  g_Allocator); fd->VertexBufferMemory = VK_NULL_HANDLE; }
        if (fd->IndexBuffer)        { vkDestroyBuffer   (g_Device, fd->IndexBuffer,         g_Allocator); fd->IndexBuffer = VK_NULL_HANDLE; }
        if (fd->IndexBufferMemory)  { vkFreeMemory      (g_Device, fd->IndexBufferMemory,   g_Allocator); fd->IndexBufferMemory = VK_NULL_HANDLE; }
    }

    if (g_FontView)             { vkDestroyImageView(g_Device, g_FontView, g_Allocator); g_FontView = VK_NULL_HANDLE; }
    if (g_FontImage)            { vkDestroyImage(g_Device, g_FontImage, g_Allocator); g_FontImage = VK_NULL_HANDLE; }
    if (g_FontMemory)           { vkFreeMemory(g_Device, g_FontMemory, g_Allocator); g_FontMemory = VK_NULL_HANDLE; }
    if (g_FontSampler)          { vkDestroySampler(g_Device, g_FontSampler, g_Allocator); g_FontSampler = VK_NULL_HANDLE; }
    if (g_DescriptorSetLayout)  { vkDestroyDescriptorSetLayout(g_Device, g_DescriptorSetLayout, g_Allocator); g_DescriptorSetLayout = VK_NULL_HANDLE; }
    if (g_PipelineLayout)       { vkDestroyPipelineLayout(g_Device, g_PipelineLayout, g_Allocator); g_PipelineLayout = VK_NULL_HANDLE; }
    if (g_Pipeline)             { vkDestroyPipeline(g_Device, g_Pipeline, g_Allocator); g_Pipeline = VK_NULL_HANDLE; }
}

bool    ImGui_ImplVulkan_Init(ImGui_ImplVulkan_InitInfo* info, VkRenderPass render_pass)
{
    ImGuiIO& io = ImGui::GetIO();
    io.BackendRendererName = "imgui_impl_vulkan";

    IM_ASSERT(info->Instance != VK_NULL_HANDLE);
    IM_ASSERT(info->PhysicalDevice != VK_NULL_HANDLE);
    IM_ASSERT(info->Device != VK_NULL_HANDLE);
    IM_ASSERT(info->Queue != VK_NULL_HANDLE);
    IM_ASSERT(info->DescriptorPool != VK_NULL_HANDLE);
    IM_ASSERT(render_pass != VK_NULL_HANDLE);

    g_Instance = info->Instance;
    g_PhysicalDevice = info->PhysicalDevice;
    g_Device = info->Device;
    g_QueueFamily = info->QueueFamily;
    g_Queue = info->Queue;
    g_RenderPass = render_pass;
    g_PipelineCache = info->PipelineCache;
    g_DescriptorPool = info->DescriptorPool;
    g_Allocator = info->Allocator;
    g_CheckVkResultFn = info->CheckVkResultFn;

    ImGui_ImplVulkan_CreateDeviceObjects();

    return true;
}

void ImGui_ImplVulkan_Shutdown()
{
    ImGui_ImplVulkan_InvalidateDeviceObjects();
}

void ImGui_ImplVulkan_NewFrame()
{
}


//-------------------------------------------------------------------------
// Internal / Miscellaneous Vulkan Helpers
//-------------------------------------------------------------------------
// 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 bindings, 
// but it is too much code to duplicate everywhere so we exceptionally expose them.
// Your application/engine 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.
// (those functions do not interact with any of the state used by the regular ImGui_ImplVulkan_XXX functions)
//-------------------------------------------------------------------------

#include <stdlib.h> // malloc

ImGui_ImplVulkanH_FrameData::ImGui_ImplVulkanH_FrameData()
{
    BackbufferIndex = 0;
    CommandPool = VK_NULL_HANDLE;
    CommandBuffer = VK_NULL_HANDLE;
    Fence = VK_NULL_HANDLE;
    ImageAcquiredSemaphore = VK_NULL_HANDLE;
    RenderCompleteSemaphore = VK_NULL_HANDLE;
}

ImGui_ImplVulkanH_WindowData::ImGui_ImplVulkanH_WindowData()
{
    Width = Height = 0;
    Swapchain = VK_NULL_HANDLE;
    Surface = VK_NULL_HANDLE;
    memset(&SurfaceFormat, 0, sizeof(SurfaceFormat));
    PresentMode = VK_PRESENT_MODE_MAX_ENUM_KHR;
    RenderPass = VK_NULL_HANDLE;
    ClearEnable = true;
    memset(&ClearValue, 0, sizeof(ClearValue));
    BackBufferCount = 0;
    memset(&BackBuffer, 0, sizeof(BackBuffer));
    memset(&BackBufferView, 0, sizeof(BackBufferView));
    memset(&Framebuffer, 0, sizeof(Framebuffer));
    FrameIndex = 0;
}

VkSurfaceFormatKHR ImGui_ImplVulkanH_SelectSurfaceFormat(VkPhysicalDevice physical_device, VkSurfaceKHR surface, const VkFormat* request_formats, int request_formats_count, VkColorSpaceKHR request_color_space)
{
    IM_ASSERT(request_formats != NULL);
    IM_ASSERT(request_formats_count > 0);

    // Per Spec Format and View Format are expected to be the same unless VK_IMAGE_CREATE_MUTABLE_BIT was set at image creation
    // Assuming that the default behavior is without setting this bit, there is no need for separate Swapchain image and image view format
    // Additionally several new color spaces were introduced with Vulkan Spec v1.0.40,
    // hence we must make sure that a format with the mostly available color space, VK_COLOR_SPACE_SRGB_NONLINEAR_KHR, is found and used.
    uint32_t avail_count;
    vkGetPhysicalDeviceSurfaceFormatsKHR(physical_device, surface, &avail_count, NULL);
    ImVector<VkSurfaceFormatKHR> avail_format;
    avail_format.resize((int)avail_count);
    vkGetPhysicalDeviceSurfaceFormatsKHR(physical_device, surface, &avail_count, avail_format.Data);

    // First check if only one format, VK_FORMAT_UNDEFINED, is available, which would imply that any format is available
    if (avail_count == 1)
    {
        if (avail_format[0].format == VK_FORMAT_UNDEFINED)
        {
            VkSurfaceFormatKHR ret;
            ret.format = request_formats[0];
            ret.colorSpace = request_color_space;
            return ret;
        }
        else
        {
            // No point in searching another format
            return avail_format[0];
        }
    }
    else
    {
        // Request several formats, the first found will be used 
        for (int request_i = 0; request_i < request_formats_count; request_i++)
            for (uint32_t avail_i = 0; avail_i < avail_count; avail_i++)
                if (avail_format[avail_i].format == request_formats[request_i] && avail_format[avail_i].colorSpace == request_color_space)
                    return avail_format[avail_i];

        // If none of the requested image formats could be found, use the first available
        return avail_format[0];
    }
}

VkPresentModeKHR ImGui_ImplVulkanH_SelectPresentMode(VkPhysicalDevice physical_device, VkSurfaceKHR surface, const VkPresentModeKHR* request_modes, int request_modes_count)
{
    IM_ASSERT(request_modes != NULL);
    IM_ASSERT(request_modes_count > 0);

    // Request a certain mode and confirm that it is available. If not use VK_PRESENT_MODE_FIFO_KHR which is mandatory
    uint32_t avail_count = 0;
    vkGetPhysicalDeviceSurfacePresentModesKHR(physical_device, surface, &avail_count, NULL);
    ImVector<VkPresentModeKHR> avail_modes;
    avail_modes.resize((int)avail_count);
    vkGetPhysicalDeviceSurfacePresentModesKHR(physical_device, surface, &avail_count, avail_modes.Data);
    //for (uint32_t avail_i = 0; avail_i < avail_count; avail_i++)
    //    printf("[vulkan] avail_modes[%d] = %d\n", avail_i, avail_modes[avail_i]);

    for (int request_i = 0; request_i < request_modes_count; request_i++)
        for (uint32_t avail_i = 0; avail_i < avail_count; avail_i++)
            if (request_modes[request_i] == avail_modes[avail_i])
                return request_modes[request_i];

    return VK_PRESENT_MODE_FIFO_KHR; // Always available
}

void ImGui_ImplVulkanH_CreateWindowDataCommandBuffers(VkPhysicalDevice physical_device, VkDevice device, uint32_t queue_family, ImGui_ImplVulkanH_WindowData* wd, const VkAllocationCallbacks* allocator)
{
    IM_ASSERT(physical_device != VK_NULL_HANDLE && device != VK_NULL_HANDLE);
    (void)physical_device;
    (void)allocator;

    // Create Command Buffers
    VkResult err;
    for (int i = 0; i < IMGUI_VK_QUEUED_FRAMES; i++)
    {
        ImGui_ImplVulkanH_FrameData* fd = &wd->Frames[i];
        {
            VkCommandPoolCreateInfo info = {};
            info.sType = VK_STRUCTURE_TYPE_COMMAND_POOL_CREATE_INFO;
            info.flags = VK_COMMAND_POOL_CREATE_RESET_COMMAND_BUFFER_BIT;
            info.queueFamilyIndex = queue_family;
            err = vkCreateCommandPool(device, &info, allocator, &fd->CommandPool);
            check_vk_result(err);
        }
        {
            VkCommandBufferAllocateInfo info = {};
            info.sType = VK_STRUCTURE_TYPE_COMMAND_BUFFER_ALLOCATE_INFO;
            info.commandPool = fd->CommandPool;
            info.level = VK_COMMAND_BUFFER_LEVEL_PRIMARY;
            info.commandBufferCount = 1;
            err = vkAllocateCommandBuffers(device, &info, &fd->CommandBuffer);
            check_vk_result(err);
        }
        {
            VkFenceCreateInfo info = {};
            info.sType = VK_STRUCTURE_TYPE_FENCE_CREATE_INFO;
            info.flags = VK_FENCE_CREATE_SIGNALED_BIT;
            err = vkCreateFence(device, &info, allocator, &fd->Fence);
            check_vk_result(err);
        }
        {
            VkSemaphoreCreateInfo info = {};
            info.sType = VK_STRUCTURE_TYPE_SEMAPHORE_CREATE_INFO;
            err = vkCreateSemaphore(device, &info, allocator, &fd->ImageAcquiredSemaphore);
            check_vk_result(err);
            err = vkCreateSemaphore(device, &info, allocator, &fd->RenderCompleteSemaphore);
            check_vk_result(err);
        }
    }
}

int ImGui_ImplVulkanH_GetMinImageCountFromPresentMode(VkPresentModeKHR present_mode)
{
    if (present_mode == VK_PRESENT_MODE_MAILBOX_KHR)
        return 3;
    if (present_mode == VK_PRESENT_MODE_FIFO_KHR || present_mode == VK_PRESENT_MODE_FIFO_RELAXED_KHR)
        return 2;
    if (present_mode == VK_PRESENT_MODE_IMMEDIATE_KHR)
        return 1;
    IM_ASSERT(0);
    return 1;
}

void ImGui_ImplVulkanH_CreateWindowDataSwapChainAndFramebuffer(VkPhysicalDevice physical_device, VkDevice device, ImGui_ImplVulkanH_WindowData* wd, const VkAllocationCallbacks* allocator, int w, int h)
{
    uint32_t min_image_count = 2;	// FIXME: this should become a function parameter

    VkResult err;
    VkSwapchainKHR old_swapchain = wd->Swapchain;
    err = vkDeviceWaitIdle(device);
    check_vk_result(err);

    // Destroy old Framebuffer
    for (uint32_t i = 0; i < wd->BackBufferCount; i++)
    {
        if (wd->BackBufferView[i])
            vkDestroyImageView(device, wd->BackBufferView[i], allocator);
        if (wd->Framebuffer[i])
            vkDestroyFramebuffer(device, wd->Framebuffer[i], allocator);
    }
    wd->BackBufferCount = 0;
    if (wd->RenderPass)
        vkDestroyRenderPass(device, wd->RenderPass, allocator);
   
    // If min image count was not specified, request different count of images dependent on selected present mode
    if (min_image_count == 0)
        min_image_count = ImGui_ImplVulkanH_GetMinImageCountFromPresentMode(wd->PresentMode);

    // Create Swapchain
    {
        VkSwapchainCreateInfoKHR info = {};
        info.sType = VK_STRUCTURE_TYPE_SWAPCHAIN_CREATE_INFO_KHR;
        info.surface = wd->Surface;
		info.minImageCount = min_image_count;
        info.imageFormat = wd->SurfaceFormat.format;
        info.imageColorSpace = wd->SurfaceFormat.colorSpace;
        info.imageArrayLayers = 1;
        info.imageUsage = VK_IMAGE_USAGE_COLOR_ATTACHMENT_BIT;
        info.imageSharingMode = VK_SHARING_MODE_EXCLUSIVE;           // Assume that graphics family == present family
        info.preTransform = VK_SURFACE_TRANSFORM_IDENTITY_BIT_KHR;
        info.compositeAlpha = VK_COMPOSITE_ALPHA_OPAQUE_BIT_KHR;
        info.presentMode = wd->PresentMode;
        info.clipped = VK_TRUE;
        info.oldSwapchain = old_swapchain;
        VkSurfaceCapabilitiesKHR cap;
        err = vkGetPhysicalDeviceSurfaceCapabilitiesKHR(physical_device, wd->Surface, &cap);
        check_vk_result(err);
        if (info.minImageCount < cap.minImageCount)
			info.minImageCount = cap.minImageCount;
		else if (cap.maxImageCount != 0 && info.minImageCount > cap.maxImageCount)
			info.minImageCount = cap.maxImageCount;

        if (cap.currentExtent.width == 0xffffffff)
        {
            info.imageExtent.width = wd->Width = w;
            info.imageExtent.height = wd->Height = h;
        }
        else
        {
            info.imageExtent.width = wd->Width = cap.currentExtent.width;
            info.imageExtent.height = wd->Height = cap.currentExtent.height;
        }
        err = vkCreateSwapchainKHR(device, &info, allocator, &wd->Swapchain);
        check_vk_result(err);
        err = vkGetSwapchainImagesKHR(device, wd->Swapchain, &wd->BackBufferCount, NULL);
        check_vk_result(err);
        err = vkGetSwapchainImagesKHR(device, wd->Swapchain, &wd->BackBufferCount, wd->BackBuffer);
        check_vk_result(err);
    }
    if (old_swapchain)
        vkDestroySwapchainKHR(device, old_swapchain, allocator);

    // Create the Render Pass
    {
        VkAttachmentDescription attachment = {};
        attachment.format = wd->SurfaceFormat.format;
        attachment.samples = VK_SAMPLE_COUNT_1_BIT;
        attachment.loadOp = wd->ClearEnable ? VK_ATTACHMENT_LOAD_OP_CLEAR : VK_ATTACHMENT_LOAD_OP_DONT_CARE;
        attachment.storeOp = VK_ATTACHMENT_STORE_OP_STORE;
        attachment.stencilLoadOp = VK_ATTACHMENT_LOAD_OP_DONT_CARE;
        attachment.stencilStoreOp = VK_ATTACHMENT_STORE_OP_DONT_CARE;
        attachment.initialLayout = VK_IMAGE_LAYOUT_UNDEFINED;
        attachment.finalLayout = VK_IMAGE_LAYOUT_PRESENT_SRC_KHR;
        VkAttachmentReference color_attachment = {};
        color_attachment.attachment = 0;
        color_attachment.layout = VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL;
        VkSubpassDescription subpass = {};
        subpass.pipelineBindPoint = VK_PIPELINE_BIND_POINT_GRAPHICS;
        subpass.colorAttachmentCount = 1;
        subpass.pColorAttachments = &color_attachment;
        VkSubpassDependency dependency = {};
        dependency.srcSubpass = VK_SUBPASS_EXTERNAL;
        dependency.dstSubpass = 0;
        dependency.srcStageMask = VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT;
        dependency.dstStageMask = VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT;
        dependency.srcAccessMask = 0;
        dependency.dstAccessMask = VK_ACCESS_COLOR_ATTACHMENT_WRITE_BIT;
        VkRenderPassCreateInfo info = {};
        info.sType = VK_STRUCTURE_TYPE_RENDER_PASS_CREATE_INFO;
        info.attachmentCount = 1;
        info.pAttachments = &attachment;
        info.subpassCount = 1;
        info.pSubpasses = &subpass;
        info.dependencyCount = 1;
        info.pDependencies = &dependency;
        err = vkCreateRenderPass(device, &info, allocator, &wd->RenderPass);
        check_vk_result(err);
    }

    // Create The Image Views
    {
        VkImageViewCreateInfo info = {};
        info.sType = VK_STRUCTURE_TYPE_IMAGE_VIEW_CREATE_INFO;
        info.viewType = VK_IMAGE_VIEW_TYPE_2D;
        info.format = wd->SurfaceFormat.format;
        info.components.r = VK_COMPONENT_SWIZZLE_R;
        info.components.g = VK_COMPONENT_SWIZZLE_G;
        info.components.b = VK_COMPONENT_SWIZZLE_B;
        info.components.a = VK_COMPONENT_SWIZZLE_A;
        VkImageSubresourceRange image_range = { VK_IMAGE_ASPECT_COLOR_BIT, 0, 1, 0, 1 };
        info.subresourceRange = image_range;
        for (uint32_t i = 0; i < wd->BackBufferCount; i++)
        {
            info.image = wd->BackBuffer[i];
            err = vkCreateImageView(device, &info, allocator, &wd->BackBufferView[i]);
            check_vk_result(err);
        }
    }

    // Create Framebuffer
    {
        VkImageView attachment[1];
        VkFramebufferCreateInfo info = {};
        info.sType = VK_STRUCTURE_TYPE_FRAMEBUFFER_CREATE_INFO;
        info.renderPass = wd->RenderPass;
        info.attachmentCount = 1;
        info.pAttachments = attachment;
        info.width = wd->Width;
        info.height = wd->Height;
        info.layers = 1;
        for (uint32_t i = 0; i < wd->BackBufferCount; i++)
        {
            attachment[0] = wd->BackBufferView[i];
            err = vkCreateFramebuffer(device, &info, allocator, &wd->Framebuffer[i]);
            check_vk_result(err);
        }
    }
}

void ImGui_ImplVulkanH_DestroyWindowData(VkInstance instance, VkDevice device, ImGui_ImplVulkanH_WindowData* wd, const VkAllocationCallbacks* allocator)
{
    vkDeviceWaitIdle(device); // FIXME: We could wait on the Queue if we had the queue in wd-> (otherwise VulkanH functions can't use globals)
    //vkQueueWaitIdle(g_Queue);

    for (int i = 0; i < IMGUI_VK_QUEUED_FRAMES; i++)
    {
        ImGui_ImplVulkanH_FrameData* fd = &wd->Frames[i];
        vkDestroyFence(device, fd->Fence, allocator);
        vkFreeCommandBuffers(device, fd->CommandPool, 1, &fd->CommandBuffer);
        vkDestroyCommandPool(device, fd->CommandPool, allocator);
        vkDestroySemaphore(device, fd->ImageAcquiredSemaphore, allocator);
        vkDestroySemaphore(device, fd->RenderCompleteSemaphore, allocator);
    }
    for (uint32_t i = 0; i < wd->BackBufferCount; i++)
    {
        vkDestroyImageView(device, wd->BackBufferView[i], allocator);
        vkDestroyFramebuffer(device, wd->Framebuffer[i], allocator);
    }
    vkDestroyRenderPass(device, wd->RenderPass, allocator);
    vkDestroySwapchainKHR(device, wd->Swapchain, allocator);
    vkDestroySurfaceKHR(instance, wd->Surface, allocator);
    *wd = ImGui_ImplVulkanH_WindowData();
}