void compressDXT5A_RGBM(ColorSet src, ColorBlock RGB, 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 = min(mina, alpha);
maxa = max(maxa, alpha);
if (alpha != 0 && alpha != 255) {
mina_no01 = min(mina_no01, alpha);
maxa_no01 = max(maxa_no01, alpha);
}
}*/
mina = 0;
maxa = 255;
mina_no01 = 0;
maxa_no01 = 255;
/*if (maxa - mina < 8) {
dst.alpha0 = maxa;
dst.alpha1 = mina;
nvDebugCheck(computeAlphaError(src, dst) == 0);
}
else if (maxa_no01 - mina_no01 < 6) {
dst.alpha0 = mina_no01;
dst.alpha1 = maxa_no01;
nvDebugCheck(computeAlphaError(src, dst) == 0);
}
else*/
{
float besterror = computeAlphaError_RGBM(src, RGB, 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_RGBM(src, RGB, 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_RGBM(src, RGB, dst, besterror);
if (error < besterror)
{
besterror = error;
besta0 = a1;
besta1 = a0;
}
}
}
}
dst.alpha0 = besta0;
dst.alpha1 = besta1;
}
computeAlphaIndices_RGBM(src, RGB, dst);
}
static void computeAlphaIndices_RGBM(ColorSet src, ColorBlock RGB, AlphaBlockDXT5 dst)
{
byte[] alphas = new byte[8];
dst.evaluatePalette(alphas, /*d3d9=*/false); // @@ Use target decoder.
for (uint i = 0; i < 16; i++)
{
float R = src.color[i].x;
float G = src.color[i].y;
float B = src.color[i].z;
float r = (float)(RGB.color[i].r) / 255.0f;
float g = (float)(RGB.color[i].g) / 255.0f;
float b = (float)(RGB.color[i].b) / 255.0f;
float minDist = float.MaxValue;
uint bestIndex = 8;
for (uint p = 0; p < 8; p++)
{
// Compute M.
float M = (float)(alphas[p]) / 255.0f * (1 - threshold) + threshold;
// Decode color.
float fr = r * M;
float fg = g * M;
float fb = b * M;
// Measure error.
float error = Mathf.Pow(R - fr, 2) + Mathf.Pow(G - fg, 2) + Mathf.Pow(B - fb, 2);
if (error < minDist)
{
minDist = error;
bestIndex = p;
}
}
dst.setIndex(i, bestIndex);
}
}
void compressDXT5A_RGBM(ColorSet src, ColorBlock RGB, 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 = min(mina, alpha);
* maxa = max(maxa, alpha);
*
* if (alpha != 0 && alpha != 255) {
* mina_no01 = min(mina_no01, alpha);
* maxa_no01 = max(maxa_no01, alpha);
* }
* }*/
mina = 0;
maxa = 255;
mina_no01 = 0;
maxa_no01 = 255;
/*if (maxa - mina < 8) {
* dst.alpha0 = maxa;
* dst.alpha1 = mina;
*
* nvDebugCheck(computeAlphaError(src, dst) == 0);
* }
* else if (maxa_no01 - mina_no01 < 6) {
* dst.alpha0 = mina_no01;
* dst.alpha1 = maxa_no01;
*
* nvDebugCheck(computeAlphaError(src, dst) == 0);
* }
* else*/
{
float besterror = computeAlphaError_RGBM(src, RGB, 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_RGBM(src, RGB, 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_RGBM(src, RGB, dst, besterror);
if (error < besterror)
{
besterror = error;
besta0 = a1;
besta1 = a0;
}
}
}
}
dst.alpha0 = besta0;
dst.alpha1 = besta1;
}
computeAlphaIndices_RGBM(src, RGB, dst);
}
static float computeAlphaError_RGBM(ColorSet src, ColorBlock RGB, AlphaBlockDXT5 dst, float bestError = float.MaxValue)
{
byte[] alphas = new byte[8];
dst.evaluatePalette(alphas, /*d3d9=*/false); // @@ Use target decoder.
float totalError = 0;
for (uint i = 0; i < 16; i++)
{
float R = src.color[i].x;
float G = src.color[i].y;
float B = src.color[i].z;
float r = (float)(RGB.color[i].r) / 255.0f;
float g = (float)(RGB.color[i].g) / 255.0f;
float b = (float)(RGB.color[i].b) / 255.0f;
float minDist = float.MaxValue;
for (uint p = 0; p < 8; p++)
{
// Compute M.
float M = (float)(alphas[p]) / 255.0f * (1 - threshold) + threshold;
// Decode color.
float fr = r * M;
float fg = g * M;
float fb = b * M;
// Measure error.
float error = Mathf.Pow(R - fr, 2) + Mathf.Pow(G - fg, 2) + Mathf.Pow(B - fb, 2);
minDist = Mathf.Min(error, minDist);
}
totalError += minDist * src.weights[i];
if (totalError > bestError)
{
// early out
return totalError;
}
}
return totalError;
}
// maxColor and minColor are expected to be in the same range as the color set.
static uint computeIndices4(ColorSet set, Vector3 maxColor, Vector3 minColor)
{
Vector3[] palette = new Vector3[4];
palette[0] = maxColor;
palette[1] = minColor;
palette[2] = Vector3.Lerp(palette[0], palette[1], 1.0f / 3.0f);
palette[3] = Vector3.Lerp(palette[0], palette[1], 2.0f / 3.0f);
Vector3[] row0 = new Vector3[6];
Vector3[] row1 = new Vector3[6];
uint indices = 0;
//for(int i = 0; i < 16; i++)
for (uint y = 0; y < 4; y++)
{
for (uint x = 0; x < 4; x++)
{
uint i = y * 4 + x;
if (!set.isValidIndex(i))
{
// Skip masked pixels and out of bounds.
continue;
}
Vector3 color = new Vector3(set.color[i].x, set.color[i].y, set.color[i].z);
// Add error.
color += row0[1 + x];
float d0 = colorDistance(palette[0], color);
float d1 = colorDistance(palette[1], color);
float d2 = colorDistance(palette[2], color);
float d3 = colorDistance(palette[3], color);
uint b0 = d0 > d3?(uint)1:(uint)0;
uint b1 = d1 > d2?(uint)1:(uint)0;
uint b2 = d0 > d2?(uint)1:(uint)0;
uint b3 = d1 > d3?(uint)1:(uint)0;
uint b4 = d2 > d3?(uint)1:(uint)0;
uint x0 = b1 & b2;
uint x1 = b0 & b3;
uint x2 = b0 & b4;
uint index = x2 | ((x0 | x1) << 1);
indices |= index << (int)(2 * i);
// Compute new error.
Vector3 diff = color - palette[index];
// Propagate new error.
//row0[1+x+1] += 7.0f / 16.0f * diff;
//row1[1+x-1] += 3.0f / 16.0f * diff;
//row1[1+x+0] += 5.0f / 16.0f * diff;
//row1[1+x+1] += 1.0f / 16.0f * diff;
}
swap(ref row0, ref row1);
row1 = new Vector3[6];
}
return(indices);
}
