Question

我有一个.DDS纹理文件，其格式为DXGI_FORMAT_BC3_UNORM，其中包含我在此处链接的10个mipmap：

https://1drv.ms/u/s!AiGFMy6hVmtN1Ba3UZsc8682VcEO

我想将此纹理的每个单独的mipmap显示到我的XAML应用程序的UI中，因此我需要将它们转换为位图。

我从DirectXTK12帮助程序库的DirectX::LoadDDSTextureFromMemory函数的第5个参数中获取每个mipmap的数据，该函数返回一个std::vector<D3D12_SUBRESOURCE_DATA>，其中填充了所有10个mipmap的数据。

我可以使用以下代码将质量最高的mipmap 0转换为位图：

std::vector<unsigned char> bytes = get_data_from_dds_file(L"WoodCrate01.dds");

std::vector<D3D12_SUBRESOURCE_DATA> subresources;
winrt::check_hresult(
    DirectX::LoadDDSTextureFromMemory(
        g_device,
        &bytes.front(),
        file_size,
        gpu_tex_resource.put(),
        subresources
    )
);

auto current_index = 0;

auto current_slice_pitch = subresources[current_index].SlicePitch;

std::vector<unsigned char> current_subresource_data;
current_subresource_data.resize(current_slice_pitch);
memcpy(&current_subresource_data[0], subresources[current_index].pData, current_slice_pitch);

Windows::Storage::Streams::InMemoryRandomAccessStream random_stream;
Windows::Storage::Streams::DataWriter writer(random_stream);

writer.WriteBytes(current_subresource_data);
co_await writer.StoreAsync();

auto decoder = co_await Windows::Graphics::Imaging::BitmapDecoder::CreateAsync(random_stream);
// Subresources at index higher than 0 crash at this point with the error: 0x88982F50 : 'The component cannot be found.'.

// The subresource at index 0 doesn't crash at the previous line, so I turn it into a SoftwareBitmap so that I can show it in XAML.
auto new_software_bitmap = co_await decoder.GetSoftwareBitmapAsync();

new_software_bitmap = Windows::Graphics::Imaging::SoftwareBitmap::Convert(
    new_software_bitmap,
    Windows::Graphics::Imaging::BitmapPixelFormat::Bgra8,
    Windows::Graphics::Imaging::BitmapAlphaMode::Premultiplied);

Windows::UI::Xaml::Media::Imaging::SoftwareBitmapSource new_bitmap_source;
co_await new_bitmap_source.SetBitmapAsync(new_software_bitmap);
[...]

当我尝试将current_index更改为1或更高时，问题开始了。在尝试创建0x88982F50 : 'The component cannot be found.'的那一行出现错误BitmapDecoder。

Answer 1

您确定源图像中包含mipmap吗？您正在调用的API不会自动生成mipmap：

"These functions create the texture resource and return the initialization data in ddsData which is pointed into by the vector of subresources. They don't support mipmaps generation, but do support reserving space for mipmaps."

查看返回的子资源的内容以查看其中的内容。

如何将Mipmap数据转换为位图？

1 个答案: