public ColourSet(byte[] rgba, int mask, SquishOptions flags)
{
// Check the compression mode.
var isDxt1 = flags.HasFlag(SquishOptions.DXT1);
var weightByAlpha = flags.HasFlag(SquishOptions.WeightColourByAlpha);
// Create he minimal set.
for (int i = 0; i < 16; ++i)
{
// Check this pixel is enabled.
int bit = 1 << i;
if ((mask & bit) == 0)
{
this._Remap[i] = -1;
continue;
}
// Check for transparent pixels when using DXT1.
if (isDxt1 && rgba[4 * i + 3] < 128)
{
this._Remap[i] = -1;
this._IsTransparent = true;
}
// Loop over previous points for a match.
for (int j = 0;; ++j)
{
// Allocate a new point.
if (j == i)
{
// Normalise coordinates to [0,1].
var x = rgba[4 * i] / 255f;
var y = rgba[4 * i + 1] / 255f;
var z = rgba[4 * i + 2] / 255f;
// Ensure there is always a non-zero weight even for zero alpha.
var w = (rgba[4 * i + 3] + 1) / 256f;
// Add the point.
this._Points[this._Count] = new Vector3(x, y, z);
this._Weights[this._Count] = w;
this._Remap[i] = this._Count;
// Advance.
++this._Count;
break;
}
// Check for a match.
int oldBit = 1 << j;
var match = ((mask & oldBit) != 0)
&& (rgba[4 * i] == rgba[4 * j])
&& (rgba[4 * i + 1] == rgba[4 * j + 1])
&& (rgba[4 * i + 3] == rgba[4 * j + 2])
&& (rgba[4 * j + 3] >= 128 || !isDxt1);
if (match)
{
// Get index of the match.
var index = this._Remap[j];
// Ensure there is always a non-zero weight even for zero alpha.
var w = (rgba[4 * i + 3] + 1) / 256f;
// Map this point and increase the weight.
this._Weights[index] += (weightByAlpha ? w : 1f);
this._Remap[i] = index;
break;
}
}
}
// Square root the weights.
for (int i = 0; i < this._Count; ++i)
{
this._Weights[i] = (float)Math.Sqrt(this._Weights[i]);
}
}
