d3d12 渲染超过最大纹理大小的bmp图片代码

如果你的图片超过了D3D12所支持的最大纹理大小，你可以使用以下代码来处理：

首先，将你的BMP图片加载到内存中。你可以使用GDI+或者DirectX Toolkit等工具来进行加载。

然后，将其分成多个小块，并将每个小块绘制到一个纹理上。你可以使用D3D12中的多个小纹理来模拟一个大纹理。

接下来，将小纹理拼接成一个大纹理。你可以使用纹理坐标来将小纹理拼接在一起。

最后，将大纹理绘制到屏幕上。

下面是一个简单的示例代码，用于将一个超过D3D12最大纹理大小的BMP图片绘制到屏幕上：

// Load the BMP image into memory
// ...

// Divide the image into small chunks and draw each chunk to a texture
const UINT ChunkSize = 2048; // The size of each chunk
const UINT ImageWidth = ...; // The width of the image
const UINT ImageHeight = ...; // The height of the image

std::vector<ID3D12Resource*> pTextureChunks;
for (UINT y = 0; y < ImageHeight; y += ChunkSize)
{
    for (UINT x = 0; x < ImageWidth; x += ChunkSize)
    {
        // Create a texture for this chunk
        CD3DX12_RESOURCE_DESC TextureDesc = CD3DX12_RESOURCE_DESC::Tex2D(
            DXGI_FORMAT_R8G8B8A8_UNORM,
            ChunkSize,
            ChunkSize,
            1, // Number of mip levels
            1  // Number of samples
        );
        ID3D12Resource* pTextureChunk;
        ThrowIfFailed(pDevice->CreateCommittedResource(
            &CD3DX12_HEAP_PROPERTIES(D3D12_HEAP_TYPE_DEFAULT),
            D3D12_HEAP_FLAG_NONE,
            &TextureDesc,
            D3D12_RESOURCE_STATE_COPY_DEST,
            nullptr,
            IID_PPV_ARGS(&pTextureChunk)));

        // Copy the chunk of the image to the texture
        D3D12_SUBRESOURCE_DATA TextureData = {};

        // Calculate the size of the chunk
        UINT ChunkWidth = min(ChunkSize, ImageWidth - x);
        UINT ChunkHeight = min(ChunkSize, ImageHeight - y);

        // Calculate the offset of the chunk in the image
        UINT ImageOffsetX = x;
        UINT ImageOffsetY = y;

        // Calculate the offset of the chunk in the texture
        UINT TextureOffsetX = 0;
        UINT TextureOffsetY = 0;

        // Set the source data
        TextureData.pData = ...; // Pointer to the chunk of the image data
        TextureData.RowPitch = ...; // The width of the chunk in bytes
        TextureData.SlicePitch = ...; // The size of the chunk in bytes

        // Copy the data to the texture
        UpdateSubresources(
            pCommandList,
            pTextureChunk,
            pTextureChunkUpload,
            0, // The start subresource index
            0, // The number of subresources to copy
            1, // The number of texture chunks
            &TextureData);

        // Add the texture chunk to the list
        pTextureChunks.push_back(pTextureChunk);
    }
}

// Combine the texture chunks into a single texture
CD3DX12_RESOURCE_DESC CombinedTextureDesc = CD3DX12_RESOURCE_DESC::Tex2D(
    DXGI_FORMAT_R8G8B8A8_UNORM,
    ImageWidth,
    ImageHeight,
    1, // Number of mip levels
    1  // Number of samples
);
ID3D12Resource* pCombinedTexture;
ThrowIfFailed(pDevice->CreateCommittedResource(
    &CD3DX12_HEAP_PROPERTIES(D3D12_HEAP_TYPE_DEFAULT),
    D3D12_HEAP_FLAG_NONE,
    &CombinedTextureDesc,
    D3D12_RESOURCE_STATE_COPY_DEST,
    nullptr,
    IID_PPV_ARGS(&pCombinedTexture)));

// Create a texture sampler
D3D12_SAMPLER_DESC SamplerDesc = {};
SamplerDesc.Filter = D3D12_FILTER_MIN_MAG_MIP_LINEAR;
SamplerDesc.AddressU = D3D12_TEXTURE_ADDRESS_MODE_WRAP;
SamplerDesc.AddressV = D3D12_TEXTURE_ADDRESS_MODE_WRAP;
SamplerDesc.AddressW = D3D12_TEXTURE_ADDRESS_MODE_WRAP;
SamplerDesc.MipLODBias = 0;
SamplerDesc.MaxAnisotropy = 1;
SamplerDesc.ComparisonFunc = D3D12_COMPARISON_FUNC_ALWAYS;
SamplerDesc.BorderColor[0] = 0.0f;
SamplerDesc.BorderColor[1] = 0.0f;
SamplerDesc.BorderColor[2] = 0.0f;
SamplerDesc.BorderColor[3] = 0.0f;
SamplerDesc.MinLOD = 0.0f;
SamplerDesc.MaxLOD = D3D12_FLOAT32_MAX;
CD3DX12_CPU_DESCRIPTOR_HANDLE SamplerHandle(pSamplerHeap->GetCPUDescriptorHandleForHeapStart());
pDevice->CreateSampler(&SamplerDesc, SamplerHandle);

// Create a shader resource view for the combined texture
D3D12_SHADER_RESOURCE_VIEW_DESC SRVDesc = {};
SRVDesc.Format = DXGI_FORMAT_R8G8B8A8_UNORM;
SRVDesc.ViewDimension = D3D12_SRV_DIMENSION_TEXTURE2D;
SRVDesc.Texture2D.MipLevels = 1;
SRVDesc.Texture2D.MostDetailedMip = 0;
CD3DX12_CPU_DESCRIPTOR_HANDLE SRVHandle(pSRVHeap->GetCPUDescriptorHandleForHeapStart());
pDevice->CreateShaderResourceView(pCombinedTexture, &SRVDesc, SRVHandle);

// Combine the texture chunks into the combined texture
for (UINT y = 0; y < ImageHeight; y += ChunkSize)
{
    for (UINT x = 0; x < ImageWidth; x += ChunkSize)
    {
        // Find the texture chunk that contains this part of the image
        UINT ChunkIndex = (y / ChunkSize) * (ImageWidth / ChunkSize) + (x / ChunkSize);
        ID3D12Resource* pTextureChunk = pTextureChunks[ChunkIndex];

        // Calculate the offset of the chunk in the image
        UINT ImageOffsetX = x;
        UINT ImageOffsetY = y;

        // Calculate the offset of the chunk in the texture
        UINT TextureOffsetX = x;
        UINT TextureOffsetY = y;

        // Copy the chunk to the combined texture
        CD3DX12_TEXTURE_COPY_LOCATION Src(pTextureChunk, 0);
        CD3DX12_TEXTURE_COPY_LOCATION Dst(pCombinedTexture, D3D12_SUBRESOURCE_INDEX_UNKNOWN, TextureOffsetX, TextureOffsetY);
        pCommandList->CopyTextureRegion(&Dst, 0, 0, 0, &Src, nullptr);
    }
}

// Draw the combined texture to the screen
// ...

请注意，这只是一个简单的示例代码，实际场景中可能需要根据具体情况进行调整。