drewcassidy/nvidia-texture-tools
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Try using 4 means clustering.

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This commit is contained in:
castano 2008-11-22 11:34:29 +00:00
parent 3a5dc4783a
commit f29d7dd938
1 changed files with 83 additions and 8 deletions
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91
src/nvtt/QuickCompressDXT.cpp
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@ -133,7 +133,7 @@ inline static float colorDistance(Vector3::Arg c0, Vector3::Arg c1)
return dot(c0-c1, c0-c1);
}
inline static uint computeIndices4(Vector3 block[16], Vector3::Arg maxColor, Vector3::Arg minColor)
inline static uint computeIndices4(const Vector3 block[16], Vector3::Arg maxColor, Vector3::Arg minColor)
{
Vector3 palette[4];
palette[0] = maxColor;
@ -165,6 +165,28 @@ inline static uint computeIndices4(Vector3 block[16], Vector3::Arg maxColor, Vec
return indices;
}
inline static float evaluatePaletteError4(const Vector3 block[16], Vector3::Arg maxColor, Vector3::Arg minColor)
{
Vector3 palette[4];
palette[0] = maxColor;
palette[1] = minColor;
palette[2] = lerp(palette[0], palette[1], 1.0f / 3.0f);
palette[3] = lerp(palette[0], palette[1], 2.0f / 3.0f);
float total = 0.0f;
for (int i = 0; i < 16; i++)
{
float d0 = colorDistance(palette[0], block[i]);
float d1 = colorDistance(palette[1], block[i]);
float d2 = colorDistance(palette[2], block[i]);
float d3 = colorDistance(palette[3], block[i]);
total += min(min(d0, d1), min(d2, d3));
}
return total;
}
inline static uint computeIndices3(const ColorBlock & rgba, Vector3::Arg maxColor, Vector3::Arg minColor)
{
Vector3 palette[4];
@ -454,7 +476,7 @@ void QuickCompress::compressDXT1(const ColorBlock & rgba, BlockDXT1 * dxtBlock)
Vector3 block[16];
extractColorBlockRGB(rgba, block);
#if 0
#if 1
// find min and max colors
Vector3 maxColor, minColor;
findMinMaxColorsBox(block, 16, &maxColor, &minColor);
@ -462,15 +484,68 @@ void QuickCompress::compressDXT1(const ColorBlock & rgba, BlockDXT1 * dxtBlock)
selectDiagonal(block, 16, &maxColor, &minColor);
insetBBox(&maxColor, &minColor);
#endif
#else
float weights[16] = {1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1};
Vector3 cluster[4];
Compute4Means(16, block, weights, Vector3(1, 1, 1), cluster);
int count = Compute4Means(16, block, weights, Vector3(1, 1, 1), cluster);
Vector3 maxColor = cluster[0];
Vector3 minColor = cluster[3];
Vector3 minColor = cluster[0];
float bestError = evaluatePaletteError4(block, maxColor, minColor);
if (count >= 2)
{
float error = evaluatePaletteError4(block, cluster[0], cluster[1]);
if (error < bestError) {
bestError = error;
maxColor = cluster[0];
minColor = cluster[1];
}
if (count >= 3)
{
error = evaluatePaletteError4(block, cluster[0], cluster[2]);
if (error < bestError) {
bestError = error;
maxColor = cluster[0];
minColor = cluster[2];
}
error = evaluatePaletteError4(block, cluster[1], cluster[2]);
if (error < bestError) {
bestError = error;
maxColor = cluster[1];
minColor = cluster[2];
}
if (count >= 4)
{
error = evaluatePaletteError4(block, cluster[0], cluster[3]);
if (error < bestError) {
bestError = error;
maxColor = cluster[0];
minColor = cluster[3];
}
error = evaluatePaletteError4(block, cluster[1], cluster[3]);
if (error < bestError) {
bestError = error;
maxColor = cluster[1];
minColor = cluster[3];
}
error = evaluatePaletteError4(block, cluster[2], cluster[3]);
if (error < bestError) {
bestError = error;
maxColor = cluster[2];
minColor = cluster[3];
}
}
}
}
#endif
uint16 color0 = roundAndExpand(&maxColor);
uint16 color1 = roundAndExpand(&minColor);