/// <summary>
/// Decodes the given block
/// </summary>
/// <param name="inBlock">Block to decode</param>
/// <param name="has1bitAlpha">Set if block contains DXT1 1-bit alpha (COMPRESSED_RGBA_S3TC_DXT1_EXT)</param>
/// <param name="isDXT1">Set if block should be decoded as DXT1, else it will be decoded as DXT3/5</param>
/// <returns></returns>
private static byte[] DecodeColorBlock(DXT1Block inBlock, bool has1bitAlpha, bool isDXT1)
{
byte[] outData = new byte[(4 * 4) * 4];
byte[,] colors = new byte[4, 4];
UnpackRgb565(inBlock.Color0, out colors[0, 2], out colors[0, 1], out colors[0, 0]);
UnpackRgb565(inBlock.Color1, out colors[1, 2], out colors[1, 1], out colors[1, 0]);
colors[0, 3] = 255;
colors[1, 3] = 255;
if (isDXT1 && inBlock.Color0 <= inBlock.Color1)
{
colors[2, 0] = (byte)((colors[0, 0] + colors[1, 0]) / 2);
colors[2, 1] = (byte)((colors[0, 1] + colors[1, 1]) / 2);
colors[2, 2] = (byte)((colors[0, 2] + colors[1, 2]) / 2);
colors[2, 3] = 255;
colors[3, 0] = 0;
colors[3, 1] = 0;
colors[3, 2] = 0;
colors[3, 3] = (byte)((has1bitAlpha && inBlock.Color0 <= inBlock.Color1) ? 0 : 0xFF);
}
else
{
colors[2, 0] = (byte)((2 * colors[0, 0] + colors[1, 0]) / 3);
colors[2, 1] = (byte)((2 * colors[0, 1] + colors[1, 1]) / 3);
colors[2, 2] = (byte)((2 * colors[0, 2] + colors[1, 2]) / 3);
colors[2, 3] = 255;
colors[3, 0] = (byte)((colors[0, 0] + 2 * colors[1, 0]) / 3);
colors[3, 1] = (byte)((colors[0, 1] + 2 * colors[1, 1]) / 3);
colors[3, 2] = (byte)((colors[0, 2] + 2 * colors[1, 2]) / 3);
colors[3, 3] = 255;
}
for (int by = 0; by < 4; by++)
{
for (int bx = 0; bx < 4; bx++)
{
byte code = inBlock.Bits[(by * 4) + bx];
for (int c = 0; c < 4; c++)
{
outData[(((by * 4) + bx) * 4) + c] = colors[code, c];
}
}
}
return(outData);
}
public DXT3Block(EndianBinaryReader reader, DXTxBlockLayout blockLayout)
{
switch (blockLayout)
{
case DXTxBlockLayout.Normal:
Alpha = reader.ReadUInt64();
Color = new DXT1Block(reader, blockLayout);
break;
case DXTxBlockLayout.PSP:
Color = new DXT1Block(reader, blockLayout);
Alpha = reader.ReadUInt64();
break;
default:
throw new Exception("Unknown block layout");
}
}
public DXT5Block(EndianBinaryReader reader, DXTxBlockLayout blockLayout)
{
byte bits_5, bits_4, bits_3, bits_2, bits_1, bits_0;
switch (blockLayout)
{
case DXTxBlockLayout.Normal:
Alpha0 = reader.ReadByte();
Alpha1 = reader.ReadByte();
bits_5 = reader.ReadByte();
bits_4 = reader.ReadByte();
bits_3 = reader.ReadByte();
bits_2 = reader.ReadByte();
bits_1 = reader.ReadByte();
bits_0 = reader.ReadByte();
Bits = DXTC.ExtractBits((((ulong)bits_0 << 40) | ((ulong)bits_1 << 32) | ((ulong)bits_2 << 24) | ((ulong)bits_3 << 16) | ((ulong)bits_4 << 8) | (ulong)bits_5), 3);
Color = new DXT1Block(reader, blockLayout);
break;
case DXTxBlockLayout.PSP:
Color = new DXT1Block(reader, blockLayout);
Alpha0 = reader.ReadByte();
Alpha1 = reader.ReadByte();
bits_5 = reader.ReadByte();
bits_4 = reader.ReadByte();
bits_3 = reader.ReadByte();
bits_2 = reader.ReadByte();
bits_1 = reader.ReadByte();
bits_0 = reader.ReadByte();
Bits = DXTC.ExtractBits((((ulong)bits_0 << 40) | ((ulong)bits_1 << 32) | ((ulong)bits_2 << 24) | ((ulong)bits_3 << 16) | ((ulong)bits_4 << 8) | (ulong)bits_5), 3);
break;
default:
throw new Exception("Unknown block layout");
}
}
private static byte[] DecodeDXT1Block(EndianBinaryReader reader, PixelDataFormat inputFormat, DXTxBlockLayout blockLayout)
{
DXT1Block inBlock = new DXT1Block(reader, blockLayout);
return(DecodeColorBlock(inBlock, (inputFormat & PixelDataFormat.MaskChannels) != PixelDataFormat.ChannelsRgb, true));
}
