private static Dds DecodeDds(Stream stream, PfimConfig config, DdsHeader header)
{
Dds dds;
switch (header.PixelFormat.FourCC)
{
case CompressionAlgorithm.D3DFMT_DXT1:
dds = new Dxt1Dds(header, config);
break;
case CompressionAlgorithm.D3DFMT_DXT2:
case CompressionAlgorithm.D3DFMT_DXT4:
throw new ArgumentException("Cannot support DXT2 or DXT4");
case CompressionAlgorithm.D3DFMT_DXT3:
dds = new Dxt3Dds(header, config);
break;
case CompressionAlgorithm.D3DFMT_DXT5:
dds = new Dxt5Dds(header, config);
break;
case CompressionAlgorithm.None:
dds = new UncompressedDds(header, config);
break;
case CompressionAlgorithm.DX10:
var header10 = new DdsHeaderDxt10(stream);
dds = header10.NewDecoder(header, config);
dds.Header10 = header10;
break;
case CompressionAlgorithm.ATI1:
case CompressionAlgorithm.BC4U:
dds = new Bc4Dds(header, config);
break;
case CompressionAlgorithm.BC4S:
dds = new Bc4sDds(header, config);
break;
case CompressionAlgorithm.ATI2:
case CompressionAlgorithm.BC5U:
dds = new Bc5Dds(header, config);
break;
case CompressionAlgorithm.BC5S:
dds = new Bc5sDds(header, config);
break;
default:
throw new ArgumentException($"FourCC: {header.PixelFormat.FourCC} not supported.");
}
dds.Decode(stream, config);
return(dds);
}
protected override int Decode(byte[] stream, byte[] data, int streamIndex, uint dataIndex, uint stride)
{
streamIndex = Bc5Dds.ExtractGradient(alpha, stream, streamIndex);
ulong alphaCodes = stream[streamIndex++];
alphaCodes |= ((ulong)stream[streamIndex++] << 8);
alphaCodes |= ((ulong)stream[streamIndex++] << 16);
alphaCodes |= ((ulong)stream[streamIndex++] << 24);
alphaCodes |= ((ulong)stream[streamIndex++] << 32);
alphaCodes |= ((ulong)stream[streamIndex++] << 40);
// Colors are stored in a pair of 16 bits
ushort color0 = stream[streamIndex++];
color0 |= (ushort)(stream[streamIndex++] << 8);
ushort color1 = (stream[streamIndex++]);
color1 |= (ushort)(stream[streamIndex++] << 8);
// Extract R5G6B5 (in that order)
colors[0].r = (byte)((color0 & 0x1f));
colors[0].g = (byte)((color0 & 0x7E0) >> 5);
colors[0].b = (byte)((color0 & 0xF800) >> 11);
colors[0].r = (byte)(colors[0].r << 3 | colors[0].r >> 2);
colors[0].g = (byte)(colors[0].g << 2 | colors[0].g >> 3);
colors[0].b = (byte)(colors[0].b << 3 | colors[0].b >> 2);
colors[1].r = (byte)((color1 & 0x1f));
colors[1].g = (byte)((color1 & 0x7E0) >> 5);
colors[1].b = (byte)((color1 & 0xF800) >> 11);
colors[1].r = (byte)(colors[1].r << 3 | colors[1].r >> 2);
colors[1].g = (byte)(colors[1].g << 2 | colors[1].g >> 3);
colors[1].b = (byte)(colors[1].b << 3 | colors[1].b >> 2);
colors[2].r = (byte)((2 * colors[0].r + colors[1].r) / 3);
colors[2].g = (byte)((2 * colors[0].g + colors[1].g) / 3);
colors[2].b = (byte)((2 * colors[0].b + colors[1].b) / 3);
colors[3].r = (byte)((colors[0].r + 2 * colors[1].r) / 3);
colors[3].g = (byte)((colors[0].g + 2 * colors[1].g) / 3);
colors[3].b = (byte)((colors[0].b + 2 * colors[1].b) / 3);
for (int alphaShift = 0; alphaShift < 48; alphaShift += 12)
{
byte rowVal = stream[streamIndex++];
for (int j = 0; j < 4; j++)
{
// 3 bits determine alpha index to use
byte alphaIndex = (byte)((alphaCodes >> (alphaShift + 3 * j)) & 0x07);
var col = colors[((rowVal >> (j * 2)) & 0x03)];
data[dataIndex++] = col.r;
data[dataIndex++] = col.g;
data[dataIndex++] = col.b;
data[dataIndex++] = alpha[alphaIndex];
}
dataIndex += PIXEL_DEPTH * (stride - DIV_SIZE);
}
return(streamIndex);
}
