// ImGui Win32 + DirectX12 binding
// You can copy and use unmodified imgui_impl_* files in your project. See main.cpp for an example of using this.
// If you use this binding you'll need to call 4 functions: ImGui_ImplXXXX_Init(), ImGui_ImplXXXX_NewFrame(), ImGui::Render() and ImGui_ImplXXXX_Shutdown().
// If you are new to ImGui, see examples/README.txt and documentation at the top of imgui.cpp.
// https://github.com/ocornut/imgui

#include <imgui.h>
#include "imgui_impl_dx12.h"

// DirectX
#include <d3d12.h>
#include <d3dcompiler.h>

struct FrameResources
{
    ID3D12Resource* IB;
    ID3D12Resource* VB;
    int VertexBufferSize;
    int IndexBufferSize;
};

// Data
static INT64                    g_Time = 0;
static INT64                    g_TicksPerSecond = 0;

static HWND                     g_hWnd = 0;
static ID3D12Device*            g_pd3dDevice = NULL;
static ID3D12GraphicsCommandList* g_pd3dCommandList = NULL;
static ID3D10Blob*              g_pVertexShaderBlob = NULL;
static ID3D10Blob*              g_pPixelShaderBlob = NULL;
static ID3D12RootSignature*     g_pRootSignature = NULL;
static ID3D12PipelineState*     g_pPipelineState = NULL;
static ID3D12Resource*          g_pFontTextureResource = NULL;
static D3D12_CPU_DESCRIPTOR_HANDLE g_hFontSrvCpuDescHandle = {};
static D3D12_GPU_DESCRIPTOR_HANDLE g_hFontSrvGpuDescHandle = {};

static FrameResources*          g_pFrameResources = NULL;
static UINT                     g_numFramesInFlight = 0;
static UINT                     g_frameIndex = UINT_MAX;

struct VERTEX_CONSTANT_BUFFER
{
    float        mvp[4][4];
};

// This is the main rendering function that you have to implement and provide to ImGui (via setting up 'RenderDrawListsFn' in the ImGuiIO structure)
// If text or lines are blurry when integrating ImGui in your engine:
// - in your Render function, try translating your projection matrix by (0.5f,0.5f) or (0.375f,0.375f)
void ImGui_ImplDX12_RenderDrawLists(ImDrawData* draw_data)
{
    // Create and grow vertex/index buffers if needed
    //
    // NOTE: I'm assuming that this only get's called once per frame!  If not,
    // we can't just re-allocate the IB or VB, we'll have to do a proper
    // allocator.
    g_frameIndex = g_frameIndex + 1;
    FrameResources* frameResources = &g_pFrameResources[g_frameIndex % g_numFramesInFlight];

    D3D12_HEAP_PROPERTIES props = {};
    props.Type = D3D12_HEAP_TYPE_UPLOAD;
    props.CPUPageProperty = D3D12_CPU_PAGE_PROPERTY_UNKNOWN;
    props.MemoryPoolPreference = D3D12_MEMORY_POOL_UNKNOWN;

    D3D12_RESOURCE_DESC desc = {};
    desc.Dimension = D3D12_RESOURCE_DIMENSION_BUFFER;
    desc.Height = 1;
    desc.DepthOrArraySize = 1;
    desc.MipLevels = 1;
    desc.Format = DXGI_FORMAT_UNKNOWN;
    desc.SampleDesc.Count = 1;
    desc.Layout = D3D12_TEXTURE_LAYOUT_ROW_MAJOR;
    desc.Flags = D3D12_RESOURCE_FLAG_NONE;

    if (!frameResources->VB || frameResources->VertexBufferSize < draw_data->TotalVtxCount)
    {
        if (frameResources->VB) { frameResources->VB->Release(); frameResources->VB = NULL; }
        frameResources->VertexBufferSize = draw_data->TotalVtxCount + 5000;
        desc.Width = frameResources->VertexBufferSize * sizeof(ImDrawVert);
        HRESULT hr = g_pd3dDevice->CreateCommittedResource(&props, D3D12_HEAP_FLAG_NONE, &desc, D3D12_RESOURCE_STATE_GENERIC_READ, NULL, IID_PPV_ARGS(&frameResources->VB));
        assert(SUCCEEDED(hr));
    }
    if (!frameResources->IB || frameResources->IndexBufferSize < draw_data->TotalIdxCount)
    {
        if (frameResources->IB) { frameResources->IB->Release(); frameResources->IB = NULL; }
        frameResources->IndexBufferSize = draw_data->TotalIdxCount + 10000;
        desc.Width = frameResources->IndexBufferSize * sizeof(ImDrawIdx);
        HRESULT hr = g_pd3dDevice->CreateCommittedResource(&props, D3D12_HEAP_FLAG_NONE, &desc, D3D12_RESOURCE_STATE_GENERIC_READ, NULL, IID_PPV_ARGS(&frameResources->IB));
        assert(SUCCEEDED(hr));
    }

    // Copy and convert all vertices into a single contiguous buffer
    D3D12_RANGE range = {};
    void* vtx_resource = NULL;
    HRESULT hr = frameResources->VB->Map(0, &range, &vtx_resource);
    assert(SUCCEEDED(hr));

    void* idx_resource = NULL;
    hr = frameResources->IB->Map(0, &range, &idx_resource);
    assert(SUCCEEDED(hr));

    ImDrawVert* vtx_dst = (ImDrawVert*)vtx_resource;
    ImDrawIdx* idx_dst = (ImDrawIdx*)idx_resource;
    for (int n = 0; n < draw_data->CmdListsCount; n++)
    {
        const ImDrawList* cmd_list = draw_data->CmdLists[n];
        memcpy(vtx_dst, &cmd_list->VtxBuffer[0], cmd_list->VtxBuffer.size() * sizeof(ImDrawVert));
        memcpy(idx_dst, &cmd_list->IdxBuffer[0], cmd_list->IdxBuffer.size() * sizeof(ImDrawIdx));
        vtx_dst += cmd_list->VtxBuffer.size();
        idx_dst += cmd_list->IdxBuffer.size();
    }
    frameResources->VB->Unmap(0, &range);
    frameResources->IB->Unmap(0, &range);

    // Setup orthographic projection matrix into our constant buffer
    VERTEX_CONSTANT_BUFFER vertexConstantBuffer = {};
    {
        const float L = 0.0f;
        const float R = ImGui::GetIO().DisplaySize.x;
        const float B = ImGui::GetIO().DisplaySize.y;
        const float T = 0.0f;
        const float mvp[4][4] =
        {
            { 2.0f/(R-L),   0.0f,           0.0f,       0.0f },
            { 0.0f,         2.0f/(T-B),     0.0f,       0.0f },
            { 0.0f,         0.0f,           0.5f,       0.0f },
            { (R+L)/(L-R),  (T+B)/(B-T),    0.5f,       1.0f },
        };
        memcpy(&vertexConstantBuffer.mvp, mvp, sizeof(mvp));
    }

    // Setup viewport
    D3D12_VIEWPORT viewport = {};
    viewport.Width = ImGui::GetIO().DisplaySize.x;
    viewport.Height = ImGui::GetIO().DisplaySize.y;
    viewport.MinDepth = 0.0f;
    viewport.MaxDepth = 1.0f;
    viewport.TopLeftX = 0;
    viewport.TopLeftY = 0;

    // Bind shader and vertex buffers
    D3D12_VERTEX_BUFFER_VIEW vbv = {};
    vbv.BufferLocation = frameResources->VB->GetGPUVirtualAddress();
    vbv.SizeInBytes = frameResources->VertexBufferSize * sizeof(ImDrawVert);
    vbv.StrideInBytes = sizeof(ImDrawVert);

    D3D12_INDEX_BUFFER_VIEW ibv = {};
    ibv.BufferLocation = frameResources->IB->GetGPUVirtualAddress();
    ibv.SizeInBytes = frameResources->IndexBufferSize * sizeof(ImDrawIdx);
    ibv.Format = sizeof(ImDrawIdx) == 2 ? DXGI_FORMAT_R16_UINT : DXGI_FORMAT_R32_UINT;

    FLOAT blendFactor[4] = { 0.f, 0.f, 0.f, 0.f };

    g_pd3dCommandList->SetPipelineState(g_pPipelineState);
    g_pd3dCommandList->SetGraphicsRootSignature(g_pRootSignature);
    g_pd3dCommandList->SetGraphicsRoot32BitConstants(0, 16, &vertexConstantBuffer, 0);
    g_pd3dCommandList->IASetIndexBuffer(&ibv);
    g_pd3dCommandList->IASetVertexBuffers(0, 1, &vbv);
    g_pd3dCommandList->IASetPrimitiveTopology(D3D_PRIMITIVE_TOPOLOGY_TRIANGLELIST);
    g_pd3dCommandList->RSSetViewports(1, &viewport);
    g_pd3dCommandList->OMSetBlendFactor(blendFactor);

    // Render command lists
    int vtx_offset = 0;
    int idx_offset = 0;
    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
            {
                D3D12_RECT scissorRect = { (LONG)pcmd->ClipRect.x, (LONG)pcmd->ClipRect.y, (LONG)pcmd->ClipRect.z, (LONG)pcmd->ClipRect.w };

                D3D12_GPU_DESCRIPTOR_HANDLE srvHandle = {};
                srvHandle.ptr = (UINT64) pcmd->TextureId;

                g_pd3dCommandList->SetGraphicsRootDescriptorTable(1, srvHandle);
                g_pd3dCommandList->RSSetScissorRects(1, &scissorRect);
                g_pd3dCommandList->DrawIndexedInstanced(pcmd->ElemCount, 1, idx_offset, vtx_offset, 0);
            }
            idx_offset += pcmd->ElemCount;
        }
        vtx_offset += cmd_list->VtxBuffer.size();
    }
}

IMGUI_API LRESULT ImGui_ImplDX12_WndProcHandler(HWND, UINT msg, WPARAM wParam, LPARAM lParam)
{
    ImGuiIO& io = ImGui::GetIO();
    switch (msg)
    {
    case WM_LBUTTONDOWN:
        io.MouseDown[0] = true;
        return true;
    case WM_LBUTTONUP:
        io.MouseDown[0] = false;
        return true;
    case WM_RBUTTONDOWN:
        io.MouseDown[1] = true;
        return true;
    case WM_RBUTTONUP:
        io.MouseDown[1] = false;
        return true;
    case WM_MBUTTONDOWN:
        io.MouseDown[2] = true;
        return true;
    case WM_MBUTTONUP:
        io.MouseDown[2] = false;
        return true;
    case WM_MOUSEWHEEL:
        io.MouseWheel += GET_WHEEL_DELTA_WPARAM(wParam) > 0 ? +1.0f : -1.0f;
        return true;
    case WM_MOUSEMOVE:
        io.MousePos.x = (signed short)(lParam);
        io.MousePos.y = (signed short)(lParam >> 16);
        return true;
    case WM_KEYDOWN:
        if (wParam < 256)
            io.KeysDown[wParam] = 1;
        return true;
    case WM_KEYUP:
        if (wParam < 256)
            io.KeysDown[wParam] = 0;
        return true;
    case WM_CHAR:
        // You can also use ToAscii()+GetKeyboardState() to retrieve characters.
        if (wParam > 0 && wParam < 0x10000)
            io.AddInputCharacter((unsigned short)wParam);
        return true;
    }
    return 0;
}

static void ImGui_ImplDX12_CreateFontsTexture()
{
    // Build texture atlas
    ImGuiIO& io = ImGui::GetIO();
    unsigned char* pixels;
    int width, height;
    io.Fonts->GetTexDataAsRGBA32(&pixels, &width, &height);

    // Upload texture to graphics system
    {
        D3D12_RESOURCE_DESC resourceDesc = {};
        resourceDesc.Dimension = D3D12_RESOURCE_DIMENSION_TEXTURE2D;
        resourceDesc.Alignment = 0;
        resourceDesc.Width = width;
        resourceDesc.Height = height;
        resourceDesc.DepthOrArraySize = 1;
        resourceDesc.MipLevels = 1;
        resourceDesc.Format = DXGI_FORMAT_R8G8B8A8_UNORM;
        resourceDesc.SampleDesc.Count = 1;
        resourceDesc.SampleDesc.Quality = 0;
        resourceDesc.Layout = D3D12_TEXTURE_LAYOUT_UNKNOWN;
        resourceDesc.Flags = D3D12_RESOURCE_FLAG_NONE;

        D3D12_HEAP_PROPERTIES props = {};
        props.Type = D3D12_HEAP_TYPE_DEFAULT;
        props.CPUPageProperty = D3D12_CPU_PAGE_PROPERTY_UNKNOWN;
        props.MemoryPoolPreference = D3D12_MEMORY_POOL_UNKNOWN;

        HRESULT hr = g_pd3dDevice->CreateCommittedResource(&props, D3D12_HEAP_FLAG_NONE, &resourceDesc,
            D3D12_RESOURCE_STATE_COPY_DEST, NULL, IID_PPV_ARGS(&g_pFontTextureResource));
        assert(SUCCEEDED(hr));

        UINT uploadPitch = (width * 4 + D3D12_TEXTURE_DATA_PITCH_ALIGNMENT - 1u) & ~(D3D12_TEXTURE_DATA_PITCH_ALIGNMENT - 1u);
        UINT uploadSize = height * uploadPitch;
        resourceDesc.Dimension = D3D12_RESOURCE_DIMENSION_BUFFER;
        resourceDesc.Alignment = 0;
        resourceDesc.Width = uploadSize;
        resourceDesc.Height = 1;
        resourceDesc.DepthOrArraySize = 1;
        resourceDesc.MipLevels = 1;
        resourceDesc.Format = DXGI_FORMAT_UNKNOWN;
        resourceDesc.SampleDesc.Count = 1;
        resourceDesc.SampleDesc.Quality = 0;
        resourceDesc.Layout = D3D12_TEXTURE_LAYOUT_ROW_MAJOR;
        resourceDesc.Flags = D3D12_RESOURCE_FLAG_NONE;

        props.Type = D3D12_HEAP_TYPE_UPLOAD;
        props.CPUPageProperty = D3D12_CPU_PAGE_PROPERTY_UNKNOWN;
        props.MemoryPoolPreference = D3D12_MEMORY_POOL_UNKNOWN;

        ID3D12Resource* uploadBuffer = NULL;
        hr = g_pd3dDevice->CreateCommittedResource(&props, D3D12_HEAP_FLAG_NONE, &resourceDesc,
            D3D12_RESOURCE_STATE_GENERIC_READ, NULL, IID_PPV_ARGS(&uploadBuffer));
        assert(SUCCEEDED(hr));

        void* mapped = NULL;
        D3D12_RANGE range = { 0, uploadSize };
        hr = uploadBuffer->Map(0, &range, &mapped);
        assert(SUCCEEDED(hr));
        for (int y = 0; y < height; ++y)
        {
            memcpy((void*) ((uintptr_t) mapped + y * uploadPitch), pixels + y * width * 4, width * 4);
        }
        uploadBuffer->Unmap(0, &range);

        D3D12_TEXTURE_COPY_LOCATION srcLocation = {};
        srcLocation.pResource = uploadBuffer;
        srcLocation.Type = D3D12_TEXTURE_COPY_TYPE_PLACED_FOOTPRINT;
        srcLocation.PlacedFootprint.Footprint.Format = DXGI_FORMAT_R8G8B8A8_UNORM;
        srcLocation.PlacedFootprint.Footprint.Width = width;
        srcLocation.PlacedFootprint.Footprint.Height = height;
        srcLocation.PlacedFootprint.Footprint.Depth = 1;
        srcLocation.PlacedFootprint.Footprint.RowPitch = uploadPitch;

        D3D12_TEXTURE_COPY_LOCATION dstLocation = {};
        dstLocation.pResource = g_pFontTextureResource;
        dstLocation.Type = D3D12_TEXTURE_COPY_TYPE_SUBRESOURCE_INDEX;
        dstLocation.SubresourceIndex = 0;

        D3D12_RESOURCE_BARRIER barrier = {};
        barrier.Type = D3D12_RESOURCE_BARRIER_TYPE_TRANSITION;
        barrier.Flags = D3D12_RESOURCE_BARRIER_FLAG_NONE;
        barrier.Transition.pResource   = g_pFontTextureResource;
        barrier.Transition.Subresource = D3D12_RESOURCE_BARRIER_ALL_SUBRESOURCES;
        barrier.Transition.StateBefore = D3D12_RESOURCE_STATE_COPY_DEST;
        barrier.Transition.StateAfter  = D3D12_RESOURCE_STATE_PIXEL_SHADER_RESOURCE;

        ID3D12Fence* fence = NULL;
        hr = g_pd3dDevice->CreateFence(0, D3D12_FENCE_FLAG_NONE, IID_PPV_ARGS(&fence));
        assert(SUCCEEDED(hr));

        HANDLE event = CreateEvent(0, 0, 0, 0);
        assert(event != NULL);

        D3D12_COMMAND_QUEUE_DESC queueDesc = {};
        queueDesc.Type     = D3D12_COMMAND_LIST_TYPE_DIRECT;
        queueDesc.Flags    = D3D12_COMMAND_QUEUE_FLAG_NONE;
        queueDesc.NodeMask = 1;

        ID3D12CommandQueue* cmdQueue = NULL;
        hr = g_pd3dDevice->CreateCommandQueue(&queueDesc, IID_PPV_ARGS(&cmdQueue));
        assert(SUCCEEDED(hr));

        ID3D12CommandAllocator* cmdAlloc = NULL;
        hr = g_pd3dDevice->CreateCommandAllocator(D3D12_COMMAND_LIST_TYPE_DIRECT, IID_PPV_ARGS(&cmdAlloc));
        assert(SUCCEEDED(hr));

        ID3D12GraphicsCommandList* cmdList = NULL;
        hr = g_pd3dDevice->CreateCommandList(0, D3D12_COMMAND_LIST_TYPE_DIRECT, cmdAlloc, NULL, IID_PPV_ARGS(&cmdList));
        assert(SUCCEEDED(hr));

        cmdList->CopyTextureRegion(&dstLocation, 0, 0, 0, &srcLocation, NULL);
        cmdList->ResourceBarrier(1, &barrier);

        hr = cmdList->Close();
        assert(SUCCEEDED(hr));

        cmdQueue->ExecuteCommandLists(1, (ID3D12CommandList* const*) &cmdList);
        hr = cmdQueue->Signal(fence, 1);
        assert(SUCCEEDED(hr));

        fence->SetEventOnCompletion(1, event);
        WaitForSingleObject(event, INFINITE);

        cmdList->Release();
        cmdAlloc->Release();
        cmdQueue->Release();
        CloseHandle(event);
        fence->Release();
        uploadBuffer->Release();
    }

    // Create texture view
    g_pd3dDevice->CreateShaderResourceView(g_pFontTextureResource, NULL, g_hFontSrvCpuDescHandle);

    // Store our identifier
    static_assert(sizeof(void*) >= sizeof(g_hFontSrvGpuDescHandle.ptr), "Can't pack descriptor handle into TexID");
    ImGui::GetIO().Fonts->TexID = (void*) g_hFontSrvGpuDescHandle.ptr;
}

bool    ImGui_ImplDX12_CreateDeviceObjects()
{
    if (!g_pd3dDevice)
        return false;
    if (g_pPipelineState)
        ImGui_ImplDX12_InvalidateDeviceObjects();

    // Create the root signature
    {
        D3D12_DESCRIPTOR_RANGE descRange = {};
        descRange.RangeType = D3D12_DESCRIPTOR_RANGE_TYPE_SRV;
        descRange.NumDescriptors = 1;
        descRange.BaseShaderRegister = 0;
        descRange.RegisterSpace = 0;
        descRange.OffsetInDescriptorsFromTableStart = 0;

        D3D12_ROOT_PARAMETER param[2] = {};

        param[0].ParameterType = D3D12_ROOT_PARAMETER_TYPE_32BIT_CONSTANTS;
        param[0].Constants.ShaderRegister = 0;
        param[0].Constants.RegisterSpace = 0;
        param[0].Constants.Num32BitValues = 16;
        param[0].ShaderVisibility = D3D12_SHADER_VISIBILITY_VERTEX;

        param[1].ParameterType = D3D12_ROOT_PARAMETER_TYPE_DESCRIPTOR_TABLE;
        param[1].DescriptorTable.NumDescriptorRanges = 1;
        param[1].DescriptorTable.pDescriptorRanges = &descRange;
        param[1].ShaderVisibility = D3D12_SHADER_VISIBILITY_PIXEL;

        D3D12_STATIC_SAMPLER_DESC staticSampler = {};
        staticSampler.Filter = D3D12_FILTER_MIN_MAG_MIP_LINEAR;
        staticSampler.AddressU = D3D12_TEXTURE_ADDRESS_MODE_WRAP;
        staticSampler.AddressV = D3D12_TEXTURE_ADDRESS_MODE_WRAP;
        staticSampler.AddressW = D3D12_TEXTURE_ADDRESS_MODE_WRAP;
        staticSampler.MipLODBias = 0.f;
        staticSampler.MaxAnisotropy = 0;
        staticSampler.ComparisonFunc = D3D12_COMPARISON_FUNC_ALWAYS;
        staticSampler.BorderColor = D3D12_STATIC_BORDER_COLOR_TRANSPARENT_BLACK;
        staticSampler.MinLOD = 0.f;
        staticSampler.MaxLOD = 0.f;
        staticSampler.ShaderRegister = 0;
        staticSampler.RegisterSpace = 0;
        staticSampler.ShaderVisibility = D3D12_SHADER_VISIBILITY_PIXEL;

        D3D12_ROOT_SIGNATURE_DESC desc = {};
        desc.NumParameters = _countof(param);
        desc.pParameters = param;
        desc.NumStaticSamplers = 1;
        desc.pStaticSamplers = &staticSampler;
        desc.Flags =
            D3D12_ROOT_SIGNATURE_FLAG_ALLOW_INPUT_ASSEMBLER_INPUT_LAYOUT |
            D3D12_ROOT_SIGNATURE_FLAG_DENY_HULL_SHADER_ROOT_ACCESS |
            D3D12_ROOT_SIGNATURE_FLAG_DENY_DOMAIN_SHADER_ROOT_ACCESS |
            D3D12_ROOT_SIGNATURE_FLAG_DENY_GEOMETRY_SHADER_ROOT_ACCESS;

        ID3DBlob* blob = NULL;
        if (D3D12SerializeRootSignature(&desc, D3D_ROOT_SIGNATURE_VERSION_1, &blob, NULL) != S_OK)
            return false;

        g_pd3dDevice->CreateRootSignature(0, blob->GetBufferPointer(), blob->GetBufferSize(), IID_PPV_ARGS(&g_pRootSignature));
        blob->Release();
    }
    // Create the pipeline state object
    {
        static const char* vertexShader = 
            "cbuffer vertexBuffer : register(b0) \
            {\
            float4x4 ProjectionMatrix; \
            };\
            struct VS_INPUT\
            {\
            float2 pos : POSITION;\
            float4 col : COLOR0;\
            float2 uv  : TEXCOORD0;\
            };\
            \
            struct PS_INPUT\
            {\
            float4 pos : SV_POSITION;\
            float4 col : COLOR0;\
            float2 uv  : TEXCOORD0;\
            };\
            \
            PS_INPUT main(VS_INPUT input)\
            {\
            PS_INPUT output;\
            output.pos = mul( ProjectionMatrix, float4(input.pos.xy, 0.f, 1.f));\
            output.col = input.col;\
            output.uv  = input.uv;\
            return output;\
            }";

        static const char* pixelShader =
            "struct PS_INPUT\
            {\
            float4 pos : SV_POSITION;\
            float4 col : COLOR0;\
            float2 uv  : TEXCOORD0;\
            };\
            SamplerState sampler0 : register(s0);\
            Texture2D texture0 : register(t0);\
            \
            float4 main(PS_INPUT input) : SV_Target\
            {\
            float4 out_col = input.col * texture0.Sample(sampler0, input.uv); \
            return out_col; \
            }";

        D3DCompile(vertexShader, strlen(vertexShader), NULL, NULL, NULL, "main", "vs_5_0", 0, 0, &g_pVertexShaderBlob, NULL);
        if (g_pVertexShaderBlob == NULL) // NB: Pass ID3D10Blob* pErrorBlob to D3DCompile() to get error showing in (const char*)pErrorBlob->GetBufferPointer(). Make sure to Release() the blob!
            return false;

        D3DCompile(pixelShader, strlen(pixelShader), NULL, NULL, NULL, "main", "ps_5_0", 0, 0, &g_pPixelShaderBlob, NULL);
        if (g_pPixelShaderBlob == NULL)  // NB: Pass ID3D10Blob* pErrorBlob to D3DCompile() to get error showing in (const char*)pErrorBlob->GetBufferPointer(). Make sure to Release() the blob!
            return false;

        D3D12_INPUT_ELEMENT_DESC localLayout[] = {
            { "POSITION", 0, DXGI_FORMAT_R32G32_FLOAT,   0, (size_t)(&((ImDrawVert*)0)->pos), D3D12_INPUT_CLASSIFICATION_PER_VERTEX_DATA, 0 },
            { "TEXCOORD", 0, DXGI_FORMAT_R32G32_FLOAT,   0, (size_t)(&((ImDrawVert*)0)->uv),  D3D12_INPUT_CLASSIFICATION_PER_VERTEX_DATA, 0 },
            { "COLOR",    0, DXGI_FORMAT_R8G8B8A8_UNORM, 0, (size_t)(&((ImDrawVert*)0)->col), D3D12_INPUT_CLASSIFICATION_PER_VERTEX_DATA, 0 },
        };

        D3D12_GRAPHICS_PIPELINE_STATE_DESC desc = {};
        desc.NodeMask              = 1;
        desc.PrimitiveTopologyType = D3D12_PRIMITIVE_TOPOLOGY_TYPE_TRIANGLE;
        desc.InputLayout           = { localLayout, _countof(localLayout) };
        desc.pRootSignature        = g_pRootSignature;
        desc.VS                    = { g_pVertexShaderBlob->GetBufferPointer(), g_pVertexShaderBlob->GetBufferSize() };
        desc.PS                    = { g_pPixelShaderBlob->GetBufferPointer(), g_pPixelShaderBlob->GetBufferSize() };
        desc.SampleMask            = UINT_MAX;
        desc.NumRenderTargets      = 1;
        desc.RTVFormats[0]         = DXGI_FORMAT_B8G8R8A8_UNORM;
        desc.SampleDesc.Count      = 1;
        desc.Flags                 = D3D12_PIPELINE_STATE_FLAG_NONE;

        desc.RasterizerState.FillMode              = D3D12_FILL_MODE_SOLID;
        desc.RasterizerState.CullMode              = D3D12_CULL_MODE_NONE;
        desc.RasterizerState.FrontCounterClockwise = FALSE;
        desc.RasterizerState.DepthBias             = D3D12_DEFAULT_DEPTH_BIAS;
        desc.RasterizerState.DepthBiasClamp        = D3D12_DEFAULT_DEPTH_BIAS_CLAMP;
        desc.RasterizerState.SlopeScaledDepthBias  = D3D12_DEFAULT_SLOPE_SCALED_DEPTH_BIAS;
        desc.RasterizerState.DepthClipEnable       = TRUE;
        desc.RasterizerState.MultisampleEnable     = FALSE;
        desc.RasterizerState.AntialiasedLineEnable = FALSE;
        desc.RasterizerState.ForcedSampleCount     = 0;
        desc.RasterizerState.ConservativeRaster    = D3D12_CONSERVATIVE_RASTERIZATION_MODE_OFF;

        desc.BlendState.AlphaToCoverageEnable = FALSE;
        desc.BlendState.RenderTarget[0].BlendEnable = TRUE;
        desc.BlendState.RenderTarget[0].SrcBlend = D3D12_BLEND_SRC_ALPHA;
        desc.BlendState.RenderTarget[0].DestBlend = D3D12_BLEND_INV_SRC_ALPHA;
        desc.BlendState.RenderTarget[0].BlendOp = D3D12_BLEND_OP_ADD;
        desc.BlendState.RenderTarget[0].SrcBlendAlpha = D3D12_BLEND_INV_SRC_ALPHA;
        desc.BlendState.RenderTarget[0].DestBlendAlpha = D3D12_BLEND_ZERO;
        desc.BlendState.RenderTarget[0].BlendOpAlpha = D3D12_BLEND_OP_ADD;
        desc.BlendState.RenderTarget[0].RenderTargetWriteMask = D3D12_COLOR_WRITE_ENABLE_ALL;

        desc.DepthStencilState.DepthEnable   = FALSE;
        desc.DepthStencilState.StencilEnable = FALSE;

        HRESULT hr = g_pd3dDevice->CreateGraphicsPipelineState(&desc, IID_PPV_ARGS(&g_pPipelineState));
        assert(SUCCEEDED(hr));
    }

    ImGui_ImplDX12_CreateFontsTexture();

    return true;
}

void    ImGui_ImplDX12_InvalidateDeviceObjects()
{
    if (!g_pd3dDevice)
        return;

    if (g_pVertexShaderBlob) { g_pVertexShaderBlob->Release(); g_pVertexShaderBlob = NULL; }
    if (g_pPixelShaderBlob) { g_pPixelShaderBlob->Release(); g_pPixelShaderBlob = NULL; }
    if (g_pRootSignature) { g_pRootSignature->Release(); g_pRootSignature = NULL; }
    if (g_pPipelineState) { g_pPipelineState->Release(); g_pPipelineState = NULL; }
    if (g_pFontTextureResource) { g_pFontTextureResource->Release(); g_pFontTextureResource = NULL; }
    for (UINT i = 0; i < g_numFramesInFlight; ++i)
    {
        if (g_pFrameResources[i].IB) { g_pFrameResources[i].IB->Release(); g_pFrameResources[i].IB = NULL; }
        if (g_pFrameResources[i].VB) { g_pFrameResources[i].VB->Release(); g_pFrameResources[i].VB = NULL; }
    }
    ImGui::GetIO().Fonts->TexID = 0;
}

bool    ImGui_ImplDX12_Init(void* hwnd, int numFramesInFlight,
                            ID3D12Device* device, ID3D12GraphicsCommandList* cmdList,
                            D3D12_CPU_DESCRIPTOR_HANDLE fontSrvCpuDescHandle,
                            D3D12_GPU_DESCRIPTOR_HANDLE fontSrvGpuDescHandle)
{
    g_hWnd = (HWND)hwnd;
    g_pd3dDevice = device;
    g_pd3dCommandList = cmdList;
    g_hFontSrvCpuDescHandle = fontSrvCpuDescHandle;
    g_hFontSrvGpuDescHandle = fontSrvGpuDescHandle;
    g_pFrameResources = new FrameResources [numFramesInFlight];
    g_numFramesInFlight = numFramesInFlight;
    g_frameIndex = UINT_MAX;

    for (int i = 0; i < numFramesInFlight; ++i)
    {
        g_pFrameResources[i].IB = NULL;
        g_pFrameResources[i].VB = NULL;
        g_pFrameResources[i].VertexBufferSize = 5000;
        g_pFrameResources[i].IndexBufferSize = 10000;
    }

    if (!QueryPerformanceFrequency((LARGE_INTEGER *)&g_TicksPerSecond))
        return false;
    if (!QueryPerformanceCounter((LARGE_INTEGER *)&g_Time))
        return false;

    ImGuiIO& io = ImGui::GetIO();
    io.KeyMap[ImGuiKey_Tab] = VK_TAB;                       // Keyboard mapping. ImGui will use those indices to peek into the io.KeyDown[] array that we will update during the application lifetime.
    io.KeyMap[ImGuiKey_LeftArrow] = VK_LEFT;
    io.KeyMap[ImGuiKey_RightArrow] = VK_RIGHT;
    io.KeyMap[ImGuiKey_UpArrow] = VK_UP;
    io.KeyMap[ImGuiKey_DownArrow] = VK_DOWN;
    io.KeyMap[ImGuiKey_PageUp] = VK_PRIOR;
    io.KeyMap[ImGuiKey_PageDown] = VK_NEXT;
    io.KeyMap[ImGuiKey_Home] = VK_HOME;
    io.KeyMap[ImGuiKey_End] = VK_END;
    io.KeyMap[ImGuiKey_Delete] = VK_DELETE;
    io.KeyMap[ImGuiKey_Backspace] = VK_BACK;
    io.KeyMap[ImGuiKey_Enter] = VK_RETURN;
    io.KeyMap[ImGuiKey_Escape] = VK_ESCAPE;
    io.KeyMap[ImGuiKey_A] = 'A';
    io.KeyMap[ImGuiKey_C] = 'C';
    io.KeyMap[ImGuiKey_V] = 'V';
    io.KeyMap[ImGuiKey_X] = 'X';
    io.KeyMap[ImGuiKey_Y] = 'Y';
    io.KeyMap[ImGuiKey_Z] = 'Z';

    io.RenderDrawListsFn = ImGui_ImplDX12_RenderDrawLists;  // Alternatively you can set this to NULL and call ImGui::GetDrawData() after ImGui::Render() to get the same ImDrawData pointer.
    io.ImeWindowHandle = g_hWnd;

    return true;
}

void ImGui_ImplDX12_Shutdown()
{
    ImGui_ImplDX12_InvalidateDeviceObjects();
    ImGui::Shutdown();
    delete[] g_pFrameResources;
    g_pd3dDevice = NULL;
    g_hWnd = (HWND)0;
    g_pd3dCommandList = NULL;
    g_hFontSrvCpuDescHandle.ptr = 0;
    g_hFontSrvGpuDescHandle.ptr = 0;
    g_pFrameResources = NULL;
    g_numFramesInFlight = 0;
    g_frameIndex = UINT_MAX;
}

void ImGui_ImplDX12_NewFrame()
{
    if (!g_pPipelineState)
        ImGui_ImplDX12_CreateDeviceObjects();

    ImGuiIO& io = ImGui::GetIO();

    // Setup display size (every frame to accommodate for window resizing)
    RECT rect;
    GetClientRect(g_hWnd, &rect);
    io.DisplaySize = ImVec2((float)(rect.right - rect.left), (float)(rect.bottom - rect.top));

    // Setup time step
    INT64 current_time;
    QueryPerformanceCounter((LARGE_INTEGER *)&current_time);
    io.DeltaTime = (float)(current_time - g_Time) / g_TicksPerSecond;
    g_Time = current_time;

    // Read keyboard modifiers inputs
    io.KeyCtrl = (GetKeyState(VK_CONTROL) & 0x8000) != 0;
    io.KeyShift = (GetKeyState(VK_SHIFT) & 0x8000) != 0;
    io.KeyAlt = (GetKeyState(VK_MENU) & 0x8000) != 0;
    // io.KeysDown : filled by WM_KEYDOWN/WM_KEYUP events
    // io.MousePos : filled by WM_MOUSEMOVE events
    // io.MouseDown : filled by WM_*BUTTON* events
    // io.MouseWheel : filled by WM_MOUSEWHEEL events

    // Hide OS mouse cursor if ImGui is drawing it
    SetCursor(io.MouseDrawCursor ? NULL : LoadCursor(NULL, IDC_ARROW));

    // Start the frame
    ImGui::NewFrame();
}