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Merge improved DXT3 compressor from trunk. Fix issue 38.

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This commit is contained in:
castano
2008-04-26 08:05:21 +00:00
parent 7bb46a4df7
commit f7bbd4b4d7
2 changed files with 40 additions and 19 deletions
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56
src/nvtt/QuickCompressDXT.cpp
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@ -288,6 +288,27 @@ static void optimizeEndPoints4(Vector3 block[16], BlockDXT1 * dxtBlock)
dxtBlock->indices = computeIndices3(block, a, b);
}*/
// Choose quantized color that produces less error. Used by DXT3 compressor.
inline static uint quantize4(uint8 a)
{
int q0 = (a >> 4) - 1;
int q1 = (a >> 4);
int q2 = (a >> 4) + 1;
q0 = (q0 << 4) | q0;
q1 = (q1 << 4) | q1;
q2 = (q2 << 4) | q2;
int d0 = abs(q0 - a);
int d1 = abs(q1 - a);
int d2 = abs(q2 - a);
if (d0 < d1 && d0 < d2) return q0 >> 4;
if (d1 < d2) return q1 >> 4;
return q2 >> 4;
}
namespace
{
static int computeGreenError(const ColorBlock & rgba, const BlockDXT1 * block)
@ -665,27 +686,24 @@ void QuickCompress::compressDXT1G(const ColorBlock & rgba, BlockDXT1 * block)
block->indices = computeGreenIndices(rgba, palette);
}
void QuickCompress::compressDXT3A(const ColorBlock & rgba, AlphaBlockDXT3 * dxtBlock)
{
// @@ Round instead of truncate. When rounding take into account bit expansion.
dxtBlock->alpha0 = rgba.color(0).a >> 4;
dxtBlock->alpha1 = rgba.color(1).a >> 4;
dxtBlock->alpha2 = rgba.color(2).a >> 4;
dxtBlock->alpha3 = rgba.color(3).a >> 4;
dxtBlock->alpha4 = rgba.color(4).a >> 4;
dxtBlock->alpha5 = rgba.color(5).a >> 4;
dxtBlock->alpha6 = rgba.color(6).a >> 4;
dxtBlock->alpha7 = rgba.color(7).a >> 4;
dxtBlock->alpha8 = rgba.color(8).a >> 4;
dxtBlock->alpha9 = rgba.color(9).a >> 4;
dxtBlock->alphaA = rgba.color(10).a >> 4;
dxtBlock->alphaB = rgba.color(11).a >> 4;
dxtBlock->alphaC = rgba.color(12).a >> 4;
dxtBlock->alphaD = rgba.color(13).a >> 4;
dxtBlock->alphaE = rgba.color(14).a >> 4;
dxtBlock->alphaF = rgba.color(15).a >> 4;
dxtBlock->alpha0 = quantize4(rgba.color(0).a);
dxtBlock->alpha1 = quantize4(rgba.color(1).a);
dxtBlock->alpha2 = quantize4(rgba.color(2).a);
dxtBlock->alpha3 = quantize4(rgba.color(3).a);
dxtBlock->alpha4 = quantize4(rgba.color(4).a);
dxtBlock->alpha5 = quantize4(rgba.color(5).a);
dxtBlock->alpha6 = quantize4(rgba.color(6).a);
dxtBlock->alpha7 = quantize4(rgba.color(7).a);
dxtBlock->alpha8 = quantize4(rgba.color(8).a);
dxtBlock->alpha9 = quantize4(rgba.color(9).a);
dxtBlock->alphaA = quantize4(rgba.color(10).a);
dxtBlock->alphaB = quantize4(rgba.color(11).a);
dxtBlock->alphaC = quantize4(rgba.color(12).a);
dxtBlock->alphaD = quantize4(rgba.color(13).a);
dxtBlock->alphaE = quantize4(rgba.color(14).a);
dxtBlock->alphaF = quantize4(rgba.color(15).a);
}
void QuickCompress::compressDXT3(const ColorBlock & rgba, BlockDXT3 * dxtBlock)