/// <summary>
/// Loads a DDS texture from an input stream.
/// </summary>
public static Texture2DInfo LoadDDSTexture(Stream inputStream, bool flipVertically = false)
{
using (var r = new BinaryFileReader(inputStream))
{
// Check the magic string.
var magicString = r.ReadBytes(4);
if (!"DDS ".EqualsASCIIBytes(magicString))
{
throw new FileFormatException($"Invalid DDS file magic string: \"{Encoding.ASCII.GetString(magicString)}\".");
}
// Deserialize the DDS file header.
var header = new DDSHeader();
header.Read(r);
if ("DX10".EqualsASCIIBytes(header.ddspf.dwFourCC))
{
var header2 = new DDSHeader_DXT10();
header2.Read(r);
}
// Figure out the texture format and load the texture data.
ExtractDDSTextureFormatAndData(header, r, out var hasMipmaps, out var ddsMipmapLevelCount, out var textureFormat, out var bytesPerPixel, out var textureData);
// Post-process the texture to generate missing mipmaps and possibly flip it vertically.
PostProcessDDSTexture((int)header.dwWidth, (int)header.dwHeight, bytesPerPixel, hasMipmaps, (int)ddsMipmapLevelCount, textureData, flipVertically);
return(new Texture2DInfo((int)header.dwWidth, (int)header.dwHeight, textureFormat, hasMipmaps, textureData));
}
}
/// <summary>
/// Extracts a DDS file's texture format and pixel data.
/// </summary>
static void ExtractDDSTextureFormatAndData(DDSHeader header, GenericReader r, out bool hasMipmaps, out uint DDSMipmapLevelCount, out TextureFormat textureFormat, out int bytesPerPixel, out byte[] textureData)
{
hasMipmaps = Utils.ContainsBitFlags((int)header.dwCaps, (int)DDSCaps.Mipmap);
// Non-mipmapped textures still have one mipmap level: the texture itself.
DDSMipmapLevelCount = hasMipmaps ? header.dwMipMapCount : 1;
// If the DDS file contains uncompressed data.
if (Utils.ContainsBitFlags((int)header.ddspf.dwFlags, (int)DDSPixelFormats.RGB))
{
// some permutation of RGB
if (!Utils.ContainsBitFlags((int)header.ddspf.dwFlags, (int)DDSPixelFormats.AlphaPixels))
{
throw new NotImplementedException("Unsupported DDS file pixel format.");
}
// some permutation of RGBA
else
{
// There should be 32 bits per pixel.
if (header.ddspf.dwRGBBitCount != 32)
{
throw new FileFormatException("Invalid DDS file pixel format.");
}
// BGRA32
if (header.ddspf.dwBBitMask == 0x000000FF && header.ddspf.dwGBitMask == 0x0000FF00 && header.ddspf.dwRBitMask == 0x00FF0000 && header.ddspf.dwABitMask == 0xFF000000)
{
textureFormat = TextureFormat.BGRA32;
bytesPerPixel = 4;
}
// ARGB32
else if (header.ddspf.dwABitMask == 0x000000FF && header.ddspf.dwRBitMask == 0x0000FF00 && header.ddspf.dwGBitMask == 0x00FF0000 && header.ddspf.dwBBitMask == 0xFF000000)
{
textureFormat = TextureFormat.ARGB32;
bytesPerPixel = 4;
}
else
{
throw new NotImplementedException("Unsupported DDS file pixel format.");
}
if (!hasMipmaps)
{
textureData = new byte[header.dwPitchOrLinearSize * header.dwHeight];
}
// Create a data buffer to hold all mipmap levels down to 1x1.
else
{
textureData = new byte[TextureUtils.CalculateMipMappedTextureDataSize((int)header.dwWidth, (int)header.dwHeight, bytesPerPixel)];
}
r.ReadRestOfBytes(textureData, 0);
}
}
else if ("DXT1".EqualsASCIIBytes(header.ddspf.dwFourCC))
{
textureFormat = TextureFormat.ARGB32;
bytesPerPixel = 4;
var compressedTextureData = r.ReadRestOfBytes();
textureData = DecodeDXT1ToARGB(compressedTextureData, header.dwWidth, header.dwHeight, header.ddspf, DDSMipmapLevelCount);
}
else if ("DXT3".EqualsASCIIBytes(header.ddspf.dwFourCC))
{
textureFormat = TextureFormat.ARGB32;
bytesPerPixel = 4;
var compressedTextureData = r.ReadRestOfBytes();
textureData = DecodeDXT3ToARGB(compressedTextureData, header.dwWidth, header.dwHeight, header.ddspf, DDSMipmapLevelCount);
}
else if ("DXT5".EqualsASCIIBytes(header.ddspf.dwFourCC))
{
textureFormat = TextureFormat.ARGB32;
bytesPerPixel = 4;
var compressedTextureData = r.ReadRestOfBytes();
textureData = DecodeDXT5ToARGB(compressedTextureData, header.dwWidth, header.dwHeight, header.ddspf, DDSMipmapLevelCount);
}
else
{
throw new NotImplementedException("Unsupported DDS file pixel format.");
}
}
