Function readDDSHeader

Source/Falcor/Utils/Image/ImageIO.cpp:412–520

Reads image information from the DDS header data contained in pHeaderData.

// Reads image information from the DDS header data contained in pHeaderData.
void readDDSHeader(ImportData& data, const void* pHeaderData, size_t& headerSize, bool loadAsSrgb)
{
    // Check magic number
    auto magic = *static_cast<const uint32_t*>(pHeaderData);
    if (magic != DDS_MAGIC)
    {
        FALCOR_THROW("Unexpected magic number for a DDS file.");
    }

    // Check size fields for both the DDS_HEADER and DDS_PIXELFORMAT structs
    auto pHeader = reinterpret_cast<const DDS_HEADER*>(static_cast<const uint8_t*>(pHeaderData) + sizeof(uint32_t));
    if (pHeader->size != sizeof(DDS_HEADER) || pHeader->ddspf.size != sizeof(DDS_PIXELFORMAT))
    {
        FALCOR_THROW("DDS header size mismatch.");
    }

    // Check for the presence of the extended DX10 header and fill in ImportData fields with their corresponding values
    data.mipLevels = (pHeader->mipMapCount == 0) ? 1 : pHeader->mipMapCount;
    auto pixelFormat = pHeader->ddspf;
    auto fourCC = pixelFormat.fourCC;
    if (fourCC == MAKEFOURCC('D', 'X', '1', '0'))
    {
        // DX10 header extension is present
        data.hasDX10Header = true;
        if (headerSize != sizeof(uint32_t) + sizeof(DDS_HEADER) + sizeof(DDS_HEADER_DXT10))
        {
            FALCOR_THROW("DX10 header extension size mismatch.");
        }
        auto pDX10Header =
            reinterpret_cast<const DDS_HEADER_DXT10*>(static_cast<const uint8_t*>(pHeaderData) + sizeof(uint32_t) + sizeof(DDS_HEADER));
        data.arraySize = pDX10Header->arraySize;
        if (data.arraySize == 0)
        {
            FALCOR_THROW("Array size cannot be zero.");
        }
        data.format = getResourceFormat(pDX10Header->dxgiFormat);
        switch (pDX10Header->resourceDimension)
        {
        case DDS_DIMENSION_TEXTURE1D:
            data.width = pHeader->width;
            data.height = 1;
            data.depth = 1;
            data.type = Resource::Type::Texture1D;
            break;
        case DDS_DIMENSION_TEXTURE2D:
            data.width = pHeader->width;
            data.height = pHeader->height;
            data.depth = 1;
            if ((pDX10Header->miscFlag & DDS_RESOURCE_MISC_TEXTURECUBE) != 0)
            {
                data.type = Resource::Type::TextureCube;
                data.arraySize *= 6;
            }
            else
            {
                data.type = Resource::Type::Texture2D;
            }
            break;