private static void CompressAlphaDxt3(byte[] rgba, int mask, ref byte[] block, int offset)
{
// quantise and pack the alpha values pairwise
for (var i = 0; i < 8; ++i)
{
// quantise down to 4 bits
var alpha1 = rgba[8 * i + 3] * (15.0f / 255.0f);
var alpha2 = rgba[8 * i + 7] * (15.0f / 255.0f);
var quant1 = ColourBlock.FloatToInt(alpha1, 15);
var quant2 = ColourBlock.FloatToInt(alpha2, 15);
// set alpha to zero where masked
var bit1 = 1 << (2 * i);
var bit2 = 1 << (2 * i + 1);
if ((mask & bit1) == 0)
{
quant1 = 0;
}
if ((mask & bit2) == 0)
{
quant2 = 0;
}
// pack into the byte
block[i + offset] = (byte)(quant1 | (quant2 << 4));
}
}
public SingleColourFit(ColourSet colours, SquishFlags flags)
: base(colours, flags)
{
// grab the single colour
var values = MColours.Points;
_mColour[0] = (byte)ColourBlock.FloatToInt(255.0f * values[0].X, 255);
_mColour[1] = (byte)ColourBlock.FloatToInt(255.0f * values[0].Y, 255);
_mColour[2] = (byte)ColourBlock.FloatToInt(255.0f * values[0].Z, 255);
// initialise the best error
_mBesterror = int.MaxValue;
}