Function GetAlphaMode

src/engine/DDSFile.cpp:492–520

#undef ISBITMASK

    static TextureAlphaMode GetAlphaMode(const DDS_HEADER* header)
    {
        if (header->ddspf.flags & DDS_FOURCC)
        {
            if (MAKEFOURCC('D', 'X', '1', '0') == header->ddspf.fourCC)
            {
                auto d3d10ext = reinterpret_cast<const DDS_HEADER_DXT10*>(reinterpret_cast<const uint8_t*>(header) + sizeof(DDS_HEADER));
                auto mode = static_cast<TextureAlphaMode>(d3d10ext->miscFlags2 & DDS_MISC_FLAGS2_ALPHA_MODE_MASK);
                switch (mode)
                {
                case TextureAlphaMode::STRAIGHT:
                case TextureAlphaMode::PREMULTIPLIED:
                case TextureAlphaMode::OPAQUE_:
                case TextureAlphaMode::CUSTOM:
                    return mode;

                default:
                    break;
                }
            }
            else if ((MAKEFOURCC('D', 'X', 'T', '2') == header->ddspf.fourCC)
                || (MAKEFOURCC('D', 'X', 'T', '4') == header->ddspf.fourCC))
            {
                return TextureAlphaMode::PREMULTIPLIED;
            }
        }

        return TextureAlphaMode::UNKNOWN;
    }

    static size_t FillTextureInfoOffsets(TextureData& textureInfo, size_t dataSize, ptrdiff_t dataOffset)
    {