internal static Bc3Block EncodeBlock(RawBlock4X4Rgba32 rawBlock)
{
var pixels = rawBlock.AsSpan;
PcaVectors.Create(pixels, out System.Numerics.Vector3 mean, out System.Numerics.Vector3 pa);
PcaVectors.GetMinMaxColor565(pixels, mean, pa, out var min, out var max);
var c0 = max;
var c1 = min;
Bc3Block best = TryColors(rawBlock, c0, c1, out float bestError);
for (int i = 0; i < maxTries; i++)
{
var(newC0, newC1) = ColorVariationGenerator.Variate565(c0, c1, i);
var block = TryColors(rawBlock, newC0, newC1, out var error);
if (error < bestError)
{
best = block;
bestError = error;
c0 = newC0;
c1 = newC1;
}
if (bestError < errorThreshold)
{
break;
}
}
best = FindAlphaValues(best, rawBlock, 5);
return(best);
}
internal static Bc3Block EncodeBlock(RawBlock4X4Rgba32 rawBlock)
{
var pixels = rawBlock.AsSpan;
PcaVectors.Create(pixels, out System.Numerics.Vector3 mean, out System.Numerics.Vector3 pa);
PcaVectors.GetMinMaxColor565(pixels, mean, pa, out var min, out var max);
var c0 = max;
var c1 = min;
if (c0.data < c1.data)
{
var c = c0;
c0 = c1;
c1 = c;
}
Bc3Block best = TryColors(rawBlock, c0, c1, out float bestError);
int lastChanged = 0;
for (int i = 0; i < maxTries; i++)
{
var(newC0, newC1) = ColorVariationGenerator.Variate565(c0, c1, i);
if (newC0.data < newC1.data)
{
var c = newC0;
newC0 = newC1;
newC1 = c;
}
var block = TryColors(rawBlock, newC0, newC1, out var error);
lastChanged++;
if (error < bestError)
{
best = block;
bestError = error;
c0 = newC0;
c1 = newC1;
lastChanged = 0;
}
if (bestError < errorThreshold || lastChanged > ColorVariationGenerator.VarPatternCount)
{
break;
}
}
best = FindAlphaValues(best, rawBlock, 8);
return(best);
}