public Color8888(Color565 color565, byte a)
{
A = a;
R = (byte)(color565.R << 3);
G = (byte)(color565.G << 2);
B = (byte)(color565.B << 3);
}
private void ParseDxt3() // https://msdn.microsoft.com/en-us/library/windows/desktop/bb694531
{
var fileOffset = 0x80;
_pixelData = new Color8888[Width * Height];
for (var y = 0; y < Height; y += 4)
{
for (var x = 0; x < Width; x += 4)
{
var baseOffset = fileOffset;
var color0 = new Color565(BitConverter.ToUInt16(_stream, fileOffset += 0x08));
var color1 = new Color565(BitConverter.ToUInt16(_stream, fileOffset += 0x02));
var color2 = (double)2 / 3 * color0 + (double)1 / 3 * color1;
var color3 = (double)1 / 3 * color0 + (double)2 / 3 * color1;
var colors = new[]
{
new Color8888(color0, 0xFF), // bit code 00
new Color8888(color1, 0xFF), // bit code 01
new Color8888(color2, 0xFF), // bit code 10
new Color8888(color3, 0xFF) // bit code 11
};
fileOffset += 0x02;
for (var i = 0; i < 4; i++)
{
var colorRow = _stream[fileOffset + i];
var alphaRow = BitConverter.ToUInt16(_stream, baseOffset + i * 2);
for (var j = 0; j < 4; j++)
{
var colorIndex = (colorRow >> (j * 2)) & 3;
var alpha = (alphaRow >> (j * 4)) & 15;
var pos = y * Width + i * Width + x + j;
_pixelData[pos] = colors[colorIndex];
_pixelData[pos].SetAlpha((byte)(alpha / 15f * 255));
}
}
fileOffset += 0x04;
}
}
}
private void ParseDxt5() // https://msdn.microsoft.com/en-us/library/windows/desktop/bb694531
{
var fileOffset = 0x80;
_pixelData = new Color8888[Width * Height];
for (var y = 0; y < Height; y += 4)
{
for (var x = 0; x < Width; x += 4)
{
var alphas = new byte[8];
alphas[0] = _stream[fileOffset];
alphas[1] = _stream[fileOffset += 0x01];
if (alphas[0] > alphas[1])
{
// 6 interpolated alpha values.
alphas[2] = (byte)((double)6 / 7 * alphas[0] + (double)1 / 7 * alphas[1]); // bit code 010
alphas[3] = (byte)((double)5 / 7 * alphas[0] + (double)2 / 7 * alphas[1]); // bit code 011
alphas[4] = (byte)((double)4 / 7 * alphas[0] + (double)3 / 7 * alphas[1]); // bit code 100
alphas[5] = (byte)((double)3 / 7 * alphas[0] + (double)4 / 7 * alphas[1]); // bit code 101
alphas[6] = (byte)((double)2 / 7 * alphas[0] + (double)5 / 7 * alphas[1]); // bit code 110
alphas[7] = (byte)((double)1 / 7 * alphas[0] + (double)6 / 7 * alphas[1]); // bit code 111
}
else
{
// 4 interpolated alpha values.
alphas[2] = (byte)((double)4 / 5 * alphas[0] + (double)1 / 5 * alphas[1]); // bit code 010
alphas[3] = (byte)((double)3 / 5 * alphas[0] + (double)2 / 5 * alphas[1]); // bit code 011
alphas[4] = (byte)((double)2 / 5 * alphas[0] + (double)3 / 5 * alphas[1]); // bit code 100
alphas[5] = (byte)((double)1 / 5 * alphas[0] + (double)4 / 5 * alphas[1]); // bit code 101
alphas[6] = 0; // bit code 110
alphas[7] = 255; // bit code 111
}
var alphaTexelUlongData = BitConverter.ToUInt64(_stream, fileOffset += 0x01);
var alphaTexelData =
alphaTexelUlongData & 0xFFFFFFFFFFFF; // remove 2 excess bytes (read 8 bytes only need 6)
var alphaTexels = new byte[16];
for (var j = 0; j < 2; j++)
{
var alphaTexelRowData = (alphaTexelData >> (j * 0x18)) & 0xFFFFFF;
for (var i = 0; i < 8; i++)
{
var index = (alphaTexelRowData >> (i * 0x03)) & 0x07;
alphaTexels[i + j * 8] = alphas[index];
}
}
var color0 = new Color565(BitConverter.ToUInt16(_stream, fileOffset += 0x06));
var color1 = new Color565(BitConverter.ToUInt16(_stream, fileOffset += 0x02));
var color2 = (double)2 / 3 * color0 + (double)1 / 3 * color1;
var color3 = (double)1 / 3 * color0 + (double)2 / 3 * color1;
var colors = new[]
{
new Color8888(color0, 0xFF), // bit code 00
new Color8888(color1, 0xFF), // bit code 01
new Color8888(color2, 0xFF), // bit code 10
new Color8888(color3, 0xFF) // bit code 11
};
var colorTexelData = BitConverter.ToUInt32(_stream, fileOffset += 0x02);
for (var j = 3; j >= 0; j--)
{
var colorTexelRowData = (colorTexelData >> (j * 0x08)) & 0xFF;
for (var i = 0; i < 4; i++)
{
var index = (colorTexelRowData >> (i * 0x02)) & 0x03;
var pos = (uint)(y * Width + j * Width + x + i);
_pixelData[pos] = colors[index];
_pixelData[pos].SetAlpha(alphaTexels[j * 4 + i]);
}
}
fileOffset += 0x04;
}
}
}