void compressDXT5A(ColorBlock src, AlphaBlockDXT5 dst)
{
AlphaBlock4x4 tmp = new AlphaBlock4x4();
tmp.init(src, 3);
compressDXT5A(tmp, dst);
}
/*static uint computeAlphaError8( ColorBlock & rgba, AlphaBlockDXT5 * block, int bestError = INT_MAX)
* {
* int totalError = 0;
*
* for (uint i = 0; i < 16; i++)
* {
* byte alpha = rgba.color[i].a;
*
* totalError += alphaDistance(alpha, nearestAlpha8(alpha, block.alpha0, block.alpha1));
*
* if (totalError > bestError)
* {
* // early out
* return totalError;
* }
* }
*
* return totalError;
* }*/
static float computeAlphaError(AlphaBlock4x4 src, AlphaBlockDXT5 dst, float bestError = float.MaxValue)
{
byte[] alphas = new byte[8];
dst.evaluatePalette(alphas, false); // @@ Use target decoder.
float totalError = 0;
for (uint i = 0; i < 16; i++)
{
byte alpha = src.alpha[i];
uint minDist = int.MaxValue;
for (uint p = 0; p < 8; p++)
{
uint dist = alphaDistance(alpha, alphas[p]);
minDist = Math.Min(dist, minDist);
}
totalError += minDist * src.weights[i];
if (totalError > bestError)
{
// early out
return(totalError);
}
}
return(totalError);
}
public static void compressDXT5A(ColorBlock src, ref AlphaBlockDXT5 dst, int iterationCount = 8)
{
AlphaBlock4x4 tmp = new AlphaBlock4x4();
tmp.init(src, 3);
compressDXT5A(tmp, ref dst, iterationCount);
}
static uint computeAlphaIndices(AlphaBlock4x4 src, AlphaBlockDXT5 block)
{
byte[] alphas = new byte[8];
block.evaluatePalette(alphas, false); // @@ Use target decoder.
uint totalError = 0;
for (uint i = 0; i < 16; i++)
{
byte alpha = src.alpha[i];
uint besterror = 256 * 256;
uint best = 8;
for (uint p = 0; p < 8; p++)
{
int d = alphas[p] - alpha;
uint error = (uint)(d * d);
if (error < besterror)
{
besterror = error;
best = p;
}
}
//nvDebugCheck(best < 8);
totalError += besterror;
block.setIndex(i, best);
}
return(totalError);
}
static void compressDXT5A(AlphaBlock4x4 src, ref AlphaBlockDXT5 dst, int iterationCount = 8)
{
byte alpha0 = 0;
byte alpha1 = 255;
// Get min/max alpha.
for (uint i = 0; i < 16; i++)
{
byte alpha = src.alpha[i];
alpha0 = Math.Max(alpha0, alpha);
alpha1 = Math.Min(alpha1, alpha);
}
AlphaBlockDXT5 block = new AlphaBlockDXT5();
block.alpha0 = (byte)(alpha0 - (alpha0 - alpha1) / 34);
block.alpha1 = (byte)(alpha1 + (alpha0 - alpha1) / 34);
uint besterror = computeAlphaIndices(src, block);
AlphaBlockDXT5 bestblock = block;
for (int i = 0; i < iterationCount; i++)
{
optimizeAlpha8(src, block);
uint error = computeAlphaIndices(src, block);
if (error >= besterror)
{
// No improvement, stop.
break;
}
if (sameIndices(block, bestblock))
{
bestblock = block;
break;
}
besterror = error;
bestblock = block;
}
;
// Copy best block to result;
dst = bestblock;
}
static void computeAlphaIndices(AlphaBlock4x4 src, AlphaBlockDXT5 dst)
{
byte[] alphas = new byte[8];
dst.evaluatePalette(alphas, /*d3d9=*/ false); // @@ Use target decoder.
for (uint i = 0; i < 16; i++)
{
byte alpha = src.alpha[i];
uint minDist = int.MaxValue;
uint bestIndex = 8;
for (uint p = 0; p < 8; p++)
{
uint dist = alphaDistance(alpha, alphas[p]);
if (dist < minDist)
{
minDist = dist;
bestIndex = p;
}
}
dst.setIndex(i, bestIndex);
}
}
void compressDXT5A(ColorBlock src, AlphaBlockDXT5 dst)
{
AlphaBlock4x4 tmp = new AlphaBlock4x4();
tmp.init(src, 3);
compressDXT5A(tmp, dst);
}
void compressDXT5A(AlphaBlock4x4 src, AlphaBlockDXT5 dst)
{
byte mina = 255;
byte maxa = 0;
byte mina_no01 = 255;
byte maxa_no01 = 0;
// Get min/max alpha.
for (uint i = 0; i < 16; i++)
{
byte alpha = src.alpha[i];
mina = Math.Min(mina, alpha);
maxa = Math.Max(maxa, alpha);
if (alpha != 0 && alpha != 255)
{
mina_no01 = Math.Min(mina_no01, alpha);
maxa_no01 = Math.Max(maxa_no01, alpha);
}
}
if (maxa - mina < 8)
{
dst.alpha0 = maxa;
dst.alpha1 = mina;
}
else if (maxa_no01 - mina_no01 < 6)
{
dst.alpha0 = mina_no01;
dst.alpha1 = maxa_no01;
}
else
{
float besterror = computeAlphaError(src, dst);
byte besta0 = maxa;
byte besta1 = mina;
// Expand search space a bit.
int alphaExpand = 8;
mina = (byte)((mina <= alphaExpand) ? 0 : mina - alphaExpand);
maxa = (byte)((maxa >= 255 - alphaExpand) ? 255 : maxa + alphaExpand);
for (byte a0 = (byte)(mina + 9); a0 < maxa; a0++)
{
for (byte a1 = mina; a1 < a0 - 8; a1++)
{
dst.alpha0 = a0;
dst.alpha1 = a1;
float error = computeAlphaError(src, dst, besterror);
if (error < besterror)
{
besterror = error;
besta0 = a0;
besta1 = a1;
}
}
}
// Try using the 6 step encoding.
/*if (mina == 0 || maxa == 255)*/
{
// Expand search space a bit.
alphaExpand = 6;
mina_no01 = (byte)((mina_no01 <= alphaExpand) ? 0 : mina_no01 - alphaExpand);
maxa_no01 = (byte)((maxa_no01 >= 255 - alphaExpand) ? 255 : maxa_no01 + alphaExpand);
for (byte a0 = (byte)(mina_no01 + 9); a0 < maxa_no01; a0++)
{
for (byte a1 = mina_no01; a1 < a0 - 8; a1++)
{
dst.alpha0 = a1;
dst.alpha1 = a0;
float error = computeAlphaError(src, dst, besterror);
if (error < besterror)
{
besterror = error;
besta0 = a1;
besta1 = a0;
}
}
}
}
dst.alpha0 = besta0;
dst.alpha1 = besta1;
}
computeAlphaIndices(src, dst);
}
static void computeAlphaIndices(AlphaBlock4x4 src, AlphaBlockDXT5 dst)
{
byte[] alphas = new byte[8];
dst.evaluatePalette(alphas, /*d3d9=*/false); // @@ Use target decoder.
for (uint i = 0; i < 16; i++)
{
byte alpha = src.alpha[i];
uint minDist = int.MaxValue;
uint bestIndex = 8;
for (uint p = 0; p < 8; p++)
{
uint dist = alphaDistance(alpha, alphas[p]);
if (dist < minDist)
{
minDist = dist;
bestIndex = p;
}
}
dst.setIndex(i, bestIndex);
}
}
/*static uint computeAlphaError8( ColorBlock & rgba, AlphaBlockDXT5 * block, int bestError = INT_MAX)
{
int totalError = 0;
for (uint i = 0; i < 16; i++)
{
byte alpha = rgba.color[i].a;
totalError += alphaDistance(alpha, nearestAlpha8(alpha, block.alpha0, block.alpha1));
if (totalError > bestError)
{
// early out
return totalError;
}
}
return totalError;
}*/
static float computeAlphaError(AlphaBlock4x4 src, AlphaBlockDXT5 dst, float bestError = float.MaxValue)
{
byte[] alphas = new byte[8];
dst.evaluatePalette(alphas, false); // @@ Use target decoder.
float totalError = 0;
for (uint i = 0; i < 16; i++)
{
byte alpha = src.alpha[i];
uint minDist = int.MaxValue;
for (uint p = 0; p < 8; p++)
{
uint dist = alphaDistance(alpha, alphas[p]);
minDist = Math.Min(dist, minDist);
}
totalError += minDist * src.weights[i];
if (totalError > bestError)
{
// early out
return totalError;
}
}
return totalError;
}
void compressDXT5A(AlphaBlock4x4 src, AlphaBlockDXT5 dst)
{
byte mina = 255;
byte maxa = 0;
byte mina_no01 = 255;
byte maxa_no01 = 0;
// Get min/max alpha.
for (uint i = 0; i < 16; i++)
{
byte alpha = src.alpha[i];
mina = Math.Min(mina, alpha);
maxa = Math.Max(maxa, alpha);
if (alpha != 0 && alpha != 255)
{
mina_no01 = Math.Min(mina_no01, alpha);
maxa_no01 = Math.Max(maxa_no01, alpha);
}
}
if (maxa - mina < 8)
{
dst.alpha0 = maxa;
dst.alpha1 = mina;
}
else if (maxa_no01 - mina_no01 < 6)
{
dst.alpha0 = mina_no01;
dst.alpha1 = maxa_no01;
}
else
{
float besterror = computeAlphaError(src, dst);
byte besta0 = maxa;
byte besta1 = mina;
// Expand search space a bit.
int alphaExpand = 8;
mina = (byte)((mina <= alphaExpand) ? 0 : mina - alphaExpand);
maxa = (byte)((maxa >= 255 - alphaExpand) ? 255 : maxa + alphaExpand);
for (byte a0 = (byte)(mina + 9); a0 < maxa; a0++)
{
for (byte a1 = mina; a1 < a0 - 8; a1++)
{
dst.alpha0 = a0;
dst.alpha1 = a1;
float error = computeAlphaError(src, dst, besterror);
if (error < besterror)
{
besterror = error;
besta0 = a0;
besta1 = a1;
}
}
}
// Try using the 6 step encoding.
/*if (mina == 0 || maxa == 255)*/
{
// Expand search space a bit.
alphaExpand = 6;
mina_no01 = (byte)((mina_no01 <= alphaExpand) ? 0 : mina_no01 - alphaExpand);
maxa_no01 = (byte)((maxa_no01 >= 255 - alphaExpand) ? 255 : maxa_no01 + alphaExpand);
for (byte a0 = (byte)(mina_no01 + 9); a0 < maxa_no01; a0++)
{
for (byte a1 = mina_no01; a1 < a0 - 8; a1++)
{
dst.alpha0 = a1;
dst.alpha1 = a0;
float error = computeAlphaError(src, dst, besterror);
if (error < besterror)
{
besterror = error;
besta0 = a1;
besta1 = a0;
}
}
}
}
dst.alpha0 = besta0;
dst.alpha1 = besta1;
}
computeAlphaIndices(src, dst);
}
static void optimizeAlpha8(AlphaBlock4x4 src, AlphaBlockDXT5 block)
{
float alpha2_sum = 0;
float beta2_sum = 0;
float alphabeta_sum = 0;
float alphax_sum = 0;
float betax_sum = 0;
for (uint i = 0; i < 16; i++)
{
uint idx = block.index(i);
float alpha;
if (idx < 2)
{
alpha = 1.0f - idx;
}
else
{
alpha = (8.0f - idx) / 7.0f;
}
float beta = 1 - alpha;
alpha2_sum += alpha * alpha;
beta2_sum += beta * beta;
alphabeta_sum += alpha * beta;
alphax_sum += alpha * src.alpha[i];
betax_sum += beta * src.alpha[i];
}
float factor = 1.0f / (alpha2_sum * beta2_sum - alphabeta_sum * alphabeta_sum);
float a = (alphax_sum * beta2_sum - betax_sum * alphabeta_sum) * factor;
float b = (betax_sum * alpha2_sum - alphax_sum * alphabeta_sum) * factor;
byte alpha0 = (byte)(Math.Min(Math.Max(a, 0.0f), 255.0f));
byte alpha1 = (byte)(Math.Min(Math.Max(b, 0.0f), 255.0f));
if (alpha0 < alpha1)
{
swap(ref alpha0, ref alpha1);
// Flip indices:
for (uint i = 0; i < 16; i++)
{
uint idx = block.index(i);
if (idx < 2)
{
block.setIndex(i, 1 - idx);
}
else
{
block.setIndex(i, 9 - idx);
}
}
}
else if (alpha0 == alpha1)
{
for (uint i = 0; i < 16; i++)
{
block.setIndex(i, 0);
}
}
block.alpha0 = alpha0;
block.alpha1 = alpha1;
}