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togles: don't use alpha channel in dxt1 decompression for textures without it
This commit is contained in:
nillerusr
parent
ceda7d8ad0
commit
dcdcf6b733
@ -3409,8 +3409,8 @@ GLvoid *uncompressDXTc(GLsizei width, GLsizei height, GLenum format, GLsizei ima
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// uncompress a DXTc image
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// get pixel size of uncompressed image => fixed RGBA
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int pixelsize = 4;
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/* if (format==COMPRESSED_RGB_S3TC_DXT1_EXT)
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pixelsize = 3;*/
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if (format == GL_COMPRESSED_RGB_S3TC_DXT1_EXT || format == GL_COMPRESSED_SRGB_S3TC_DXT1_EXT)
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pixelsize = 3;
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// check with the size of the input data stream if the stream is in fact uncompressed
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if (imageSize == width*height*pixelsize || data==NULL) {
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// uncompressed stream
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@ -3470,15 +3470,15 @@ void CompressedTexImage2D(GLenum target, GLint level, GLenum internalformat,
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return;
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}
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GLenum format = GL_RGBA;
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GLenum intformat = GL_RGBA;
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GLenum type = GL_UNSIGNED_BYTE;
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bool hasAlpha = (internalformat != GL_COMPRESSED_RGB_S3TC_DXT1_EXT) && (internalformat != GL_COMPRESSED_SRGB_S3TC_DXT1_EXT);
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GLenum format = hasAlpha ? GL_RGBA : GL_RGB;
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GLenum intformat = hasAlpha ? GL_RGBA8 : GL_RGB8;
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GLenum type = GL_UNSIGNED_BYTE;
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GLvoid *pixels = NULL;
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if (isDXTc(internalformat)) {
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pixels = NULL;
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type = GL_UNSIGNED_BYTE;
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if (isDXTc(internalformat))
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{
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int srgb = isDXTcSRGB(internalformat);
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int simpleAlpha = 0;
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int complexAlpha = 0;
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@ -3492,7 +3492,7 @@ void CompressedTexImage2D(GLenum target, GLint level, GLenum internalformat,
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}
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if( srgb )
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intformat = GL_SRGB8_ALPHA8;
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intformat = hasAlpha ? GL_SRGB8_ALPHA8 : GL_SRGB8;
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}
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gGL->glTexImage2D(target, level, intformat, width, height, border, format, type, pixels);
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@ -92,18 +92,17 @@ static void DecompressBlockDXT1Internal (const uint8_t* block,
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code = *(const uint32_t*)(block + 4);
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if (color0 > color1) {
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for (j = 0; j < 4; ++j) {
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for (i = 0; i < 4; ++i) {
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uint32_t finalColor, positionCode;
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uint8_t alpha;
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for (j = 0; j < 4; ++j) {
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for (i = 0; i < 4; ++i) {
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uint32_t finalColor, positionCode;
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uint8_t alpha;
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alpha = alphaValues [j*4+i];
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finalColor = 0; positionCode = (code >> 2*(4*j+i)) & 0x03;
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alpha = alphaValues [j*4+i];
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finalColor = 0;
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positionCode = (code >> 2*(4*j+i)) & 0x03;
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switch (positionCode) {
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if (color0 > color1) {
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switch (positionCode)
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{
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case 0:
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finalColor = PackRGBA(r0, g0, b0, alpha);
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break;
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@ -117,24 +116,7 @@ static void DecompressBlockDXT1Internal (const uint8_t* block,
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finalColor = PackRGBA((r0+2*r1)/3, (g0+2*g1)/3, (b0+2*b1)/3, alpha);
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break;
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}
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if(!alpha)
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*simpleAlpha = 1;
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else if(alpha<0xff)
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*complexAlpha = 1;
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output [j*outputStride + i] = finalColor;
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}
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}
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} else {
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for (j = 0; j < 4; ++j) {
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for (i = 0; i < 4; ++i) {
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uint32_t finalColor, positionCode;
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uint8_t alpha;
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alpha = alphaValues [j*4+i];
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finalColor = 0;
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positionCode = (code >> 2*(4*j+i)) & 0x03;
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} else {
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switch (positionCode) {
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case 0:
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finalColor = PackRGBA(r0, g0, b0, alpha);
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@ -150,18 +132,95 @@ static void DecompressBlockDXT1Internal (const uint8_t* block,
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finalColor = PackRGBA(0, 0, 0, alpha);
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break;
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}
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if(!alpha)
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*simpleAlpha = 1;
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else if(alpha<0xff)
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*complexAlpha = 1;
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output [j*outputStride + i] = finalColor;
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}
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if(!alpha)
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*simpleAlpha = 1;
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else if(alpha<0xff)
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*complexAlpha = 1;
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output [j*outputStride + i] = finalColor;
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}
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}
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}
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static void DecompressBlockDXT1InternalRGB(const uint8_t* block, uint8_t* output, uint32_t outputStride)
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{
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uint32_t temp, code;
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uint16_t color0, color1;
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uint8_t r0, g0, b0, r1, g1, b1;
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int i, j;
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color0 = *(const uint16_t*)(block);
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color1 = *(const uint16_t*)(block + 2);
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temp = (color0 >> 11) * 255 + 16;
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r0 = (uint8_t)((temp/32 + temp)/32);
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temp = ((color0 & 0x07E0) >> 5) * 255 + 32;
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g0 = (uint8_t)((temp/64 + temp)/64);
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temp = (color0 & 0x001F) * 255 + 16;
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b0 = (uint8_t)((temp/32 + temp)/32);
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temp = (color1 >> 11) * 255 + 16;
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r1 = (uint8_t)((temp/32 + temp)/32);
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temp = ((color1 & 0x07E0) >> 5) * 255 + 32;
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g1 = (uint8_t)((temp/64 + temp)/64);
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temp = (color1 & 0x001F) * 255 + 16;
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b1 = (uint8_t)((temp/32 + temp)/32);
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code = *(const uint32_t*)(block + 4);
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for (j = 0; j < 4; ++j) {
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for (i = 0; i < 4; ++i) {
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uint8_t positionCode, finalR, finalG, finalB;
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positionCode = (code >> 2*(4*j+i)) & 0x03;
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if (color0 > color1) {
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switch (positionCode) {
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case 0:
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finalR = r0; finalG = g0; finalB = b0;
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break;
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case 1:
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finalR = r1; finalG = g1; finalB = b1;
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break;
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case 2:
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finalR = (2*r0+r1)/3; finalG = (2*g0+g1)/3; finalB = (2*b0+b1)/3;
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break;
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case 3:
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finalR = (r0+2*r1)/3; finalG = (g0+2*g1)/3; finalB = (b0+2*b1)/3;
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break;
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}
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} else {
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switch (positionCode) {
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case 0:
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finalR = r0; finalG = g0; finalB = b0;
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break;
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case 1:
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finalR = r1; finalG = g1; finalB = b1;
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break;
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case 2:
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finalR = (r0+r1)/2; finalG = (g0+g1)/2; finalB = (b0+b1)/2;
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break;
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case 3:
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finalR = finalG = finalB = 0;
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break;
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}
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}
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output[j*outputStride*3 + i*3] = finalR;
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output[j*outputStride*3 + i*3+1] = finalG;
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output[j*outputStride*3 + i*3+2] = finalB;
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}
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}
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}
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/*
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void DecompressBlockDXT1(): Decompresses one block of a DXT1 texture and stores the resulting pixels at the appropriate offset in 'image'.
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@ -176,6 +235,7 @@ void DecompressBlockDXT1(uint32_t x, uint32_t y, uint32_t width,
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int transparent0, int* simpleAlpha, int *complexAlpha,
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uint32_t* image)
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{
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static const uint8_t const_alpha [] = {
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255, 255, 255, 255,
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255, 255, 255, 255,
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@ -183,8 +243,12 @@ void DecompressBlockDXT1(uint32_t x, uint32_t y, uint32_t width,
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255, 255, 255, 255
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};
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DecompressBlockDXT1Internal (blockStorage,
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image + x + (y * width), width, transparent0, simpleAlpha, complexAlpha, const_alpha);
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if( transparent0 )
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DecompressBlockDXT1Internal (blockStorage,
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image + x + (y * width), width, transparent0, simpleAlpha, complexAlpha, const_alpha);
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else
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DecompressBlockDXT1InternalRGB(blockStorage, ((uint8_t*)image) + x*3 + (y*3 * width), width);
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}
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/*
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@ -331,11 +395,3 @@ void DecompressBlockDXT3(uint32_t x, uint32_t y, uint32_t width,
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DecompressBlockDXT1Internal (blockStorage,
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image + x + (y * width), width, transparent0, simpleAlpha, complexAlpha, alphaValues);
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}
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// Texture DXT1 / DXT5 compression
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// Using STB "on file" library
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// go there https://github.com/nothings/stb
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// for more details and other libs
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#define STB_DXT_IMPLEMENTATION
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#include "stb_dxt_104.h"
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@ -1,624 +0,0 @@
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// stb_dxt.h - v1.04 - DXT1/DXT5 compressor - public domain
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// original by fabian "ryg" giesen - ported to C by stb
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// use '#define STB_DXT_IMPLEMENTATION' before including to create the implementation
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//
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// USAGE:
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// call stb_compress_dxt_block() for every block (you must pad)
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// source should be a 4x4 block of RGBA data in row-major order;
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// A is ignored if you specify alpha=0; you can turn on dithering
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// and "high quality" using mode.
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//
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// version history:
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// v1.04 - (ryg) default to no rounding bias for lerped colors (as per S3TC/DX10 spec);
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// single color match fix (allow for inexact color interpolation);
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// optimal DXT5 index finder; "high quality" mode that runs multiple refinement steps.
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// v1.03 - (stb) endianness support
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// v1.02 - (stb) fix alpha encoding bug
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// v1.01 - (stb) fix bug converting to RGB that messed up quality, thanks ryg & cbloom
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// v1.00 - (stb) first release
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#ifndef STB_INCLUDE_STB_DXT_H
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#define STB_INCLUDE_STB_DXT_H
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// compression mode (bitflags)
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#define STB_DXT_NORMAL 0
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#define STB_DXT_DITHER 1 // use dithering. dubious win. never use for normal maps and the like!
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#define STB_DXT_HIGHQUAL 2 // high quality mode, does two refinement steps instead of 1. ~30-40% slower.
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void stb_compress_dxt_block(unsigned char *dest, const unsigned char *src, int alpha, int mode);
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#define STB_COMPRESS_DXT_BLOCK
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#ifdef STB_DXT_IMPLEMENTATION
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// configuration options for DXT encoder. set them in the project/makefile or just define
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// them at the top.
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// STB_DXT_USE_ROUNDING_BIAS
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// use a rounding bias during color interpolation. this is closer to what "ideal"
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// interpolation would do but doesn't match the S3TC/DX10 spec. old versions (pre-1.03)
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// implicitly had this turned on.
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//
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// in case you're targeting a specific type of hardware (e.g. console programmers):
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// NVidia and Intel GPUs (as of 2010) as well as DX9 ref use DXT decoders that are closer
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// to STB_DXT_USE_ROUNDING_BIAS. AMD/ATI, S3 and DX10 ref are closer to rounding with no bias.
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// you also see "(a*5 + b*3) / 8" on some old GPU designs.
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// #define STB_DXT_USE_ROUNDING_BIAS
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#include <stdlib.h>
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#include <math.h>
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#include <string.h> // memset
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static unsigned char stb__Expand5[32];
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static unsigned char stb__Expand6[64];
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static unsigned char stb__OMatch5[256][2];
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static unsigned char stb__OMatch6[256][2];
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static unsigned char stb__QuantRBTab[256+16];
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static unsigned char stb__QuantGTab[256+16];
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static int stb__Mul8Bit(int a, int b)
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{
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int t = a*b + 128;
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return (t + (t >> 8)) >> 8;
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}
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static void stb__From16Bit(unsigned char *out, unsigned short v)
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{
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int rv = (v & 0xf800) >> 11;
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int gv = (v & 0x07e0) >> 5;
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int bv = (v & 0x001f) >> 0;
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out[0] = stb__Expand5[rv];
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out[1] = stb__Expand6[gv];
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out[2] = stb__Expand5[bv];
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out[3] = 0;
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}
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static unsigned short stb__As16Bit(int r, int g, int b)
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{
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return (stb__Mul8Bit(r,31) << 11) + (stb__Mul8Bit(g,63) << 5) + stb__Mul8Bit(b,31);
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}
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// linear interpolation at 1/3 point between a and b, using desired rounding type
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static int stb__Lerp13(int a, int b)
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{
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#ifdef STB_DXT_USE_ROUNDING_BIAS
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// with rounding bias
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return a + stb__Mul8Bit(b-a, 0x55);
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#else
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// without rounding bias
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// replace "/ 3" by "* 0xaaab) >> 17" if your compiler sucks or you really need every ounce of speed.
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return (2*a + b) / 3;
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#endif
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}
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// lerp RGB color
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static void stb__Lerp13RGB(unsigned char *out, unsigned char *p1, unsigned char *p2)
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{
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out[0] = stb__Lerp13(p1[0], p2[0]);
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out[1] = stb__Lerp13(p1[1], p2[1]);
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out[2] = stb__Lerp13(p1[2], p2[2]);
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}
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/****************************************************************************/
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// compute table to reproduce constant colors as accurately as possible
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static void stb__PrepareOptTable(unsigned char *Table,const unsigned char *expand,int size)
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{
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int i,mn,mx;
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for (i=0;i<256;i++) {
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int bestErr = 256;
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for (mn=0;mn<size;mn++) {
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for (mx=0;mx<size;mx++) {
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int mine = expand[mn];
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int maxe = expand[mx];
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int err = abs(stb__Lerp13(maxe, mine) - i);
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// DX10 spec says that interpolation must be within 3% of "correct" result,
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// add this as error term. (normally we'd expect a random distribution of
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// +-1.5% error, but nowhere in the spec does it say that the error has to be
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// unbiased - better safe than sorry).
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err += abs(maxe - mine) * 3 / 100;
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if(err < bestErr)
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{
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Table[i*2+0] = mx;
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Table[i*2+1] = mn;
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bestErr = err;
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}
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}
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}
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}
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}
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static void stb__EvalColors(unsigned char *color,unsigned short c0,unsigned short c1)
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{
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stb__From16Bit(color+ 0, c0);
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stb__From16Bit(color+ 4, c1);
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stb__Lerp13RGB(color+ 8, color+0, color+4);
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stb__Lerp13RGB(color+12, color+4, color+0);
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}
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// Block dithering function. Simply dithers a block to 565 RGB.
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// (Floyd-Steinberg)
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static void stb__DitherBlock(unsigned char *dest, unsigned char *block)
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{
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int err[8],*ep1 = err,*ep2 = err+4, *et;
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int ch,y;
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// process channels seperately
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for (ch=0; ch<3; ++ch) {
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unsigned char *bp = block+ch, *dp = dest+ch;
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unsigned char *quant = (ch == 1) ? stb__QuantGTab+8 : stb__QuantRBTab+8;
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memset(err, 0, sizeof(err));
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for(y=0; y<4; ++y) {
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dp[ 0] = quant[bp[ 0] + ((3*ep2[1] + 5*ep2[0]) >> 4)];
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ep1[0] = bp[ 0] - dp[ 0];
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dp[ 4] = quant[bp[ 4] + ((7*ep1[0] + 3*ep2[2] + 5*ep2[1] + ep2[0]) >> 4)];
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ep1[1] = bp[ 4] - dp[ 4];
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dp[ 8] = quant[bp[ 8] + ((7*ep1[1] + 3*ep2[3] + 5*ep2[2] + ep2[1]) >> 4)];
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ep1[2] = bp[ 8] - dp[ 8];
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dp[12] = quant[bp[12] + ((7*ep1[2] + 5*ep2[3] + ep2[2]) >> 4)];
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ep1[3] = bp[12] - dp[12];
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bp += 16;
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dp += 16;
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et = ep1, ep1 = ep2, ep2 = et; // swap
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}
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}
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}
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// The color matching function
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static unsigned int stb__MatchColorsBlock(unsigned char *block, unsigned char *color,int dither)
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{
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unsigned int mask = 0;
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int dirr = color[0*4+0] - color[1*4+0];
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int dirg = color[0*4+1] - color[1*4+1];
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int dirb = color[0*4+2] - color[1*4+2];
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int dots[16];
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int stops[4];
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int i;
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int c0Point, halfPoint, c3Point;
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for(i=0;i<16;i++)
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dots[i] = block[i*4+0]*dirr + block[i*4+1]*dirg + block[i*4+2]*dirb;
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for(i=0;i<4;i++)
|
||||
stops[i] = color[i*4+0]*dirr + color[i*4+1]*dirg + color[i*4+2]*dirb;
|
||||
|
||||
// think of the colors as arranged on a line; project point onto that line, then choose
|
||||
// next color out of available ones. we compute the crossover points for "best color in top
|
||||
// half"/"best in bottom half" and then the same inside that subinterval.
|
||||
//
|
||||
// relying on this 1d approximation isn't always optimal in terms of euclidean distance,
|
||||
// but it's very close and a lot faster.
|
||||
// http://cbloomrants.blogspot.com/2008/12/12-08-08-dxtc-summary.html
|
||||
|
||||
c0Point = (stops[1] + stops[3]) >> 1;
|
||||
halfPoint = (stops[3] + stops[2]) >> 1;
|
||||
c3Point = (stops[2] + stops[0]) >> 1;
|
||||
|
||||
if(!dither) {
|
||||
// the version without dithering is straightforward
|
||||
for (i=15;i>=0;i--) {
|
||||
int dot = dots[i];
|
||||
mask <<= 2;
|
||||
|
||||
if(dot < halfPoint)
|
||||
mask |= (dot < c0Point) ? 1 : 3;
|
||||
else
|
||||
mask |= (dot < c3Point) ? 2 : 0;
|
||||
}
|
||||
} else {
|
||||
// with floyd-steinberg dithering
|
||||
int err[8],*ep1 = err,*ep2 = err+4;
|
||||
int *dp = dots, y;
|
||||
|
||||
c0Point <<= 4;
|
||||
halfPoint <<= 4;
|
||||
c3Point <<= 4;
|
||||
for(i=0;i<8;i++)
|
||||
err[i] = 0;
|
||||
|
||||
for(y=0;y<4;y++)
|
||||
{
|
||||
int dot,lmask,step;
|
||||
|
||||
dot = (dp[0] << 4) + (3*ep2[1] + 5*ep2[0]);
|
||||
if(dot < halfPoint)
|
||||
step = (dot < c0Point) ? 1 : 3;
|
||||
else
|
||||
step = (dot < c3Point) ? 2 : 0;
|
||||
ep1[0] = dp[0] - stops[step];
|
||||
lmask = step;
|
||||
|
||||
dot = (dp[1] << 4) + (7*ep1[0] + 3*ep2[2] + 5*ep2[1] + ep2[0]);
|
||||
if(dot < halfPoint)
|
||||
step = (dot < c0Point) ? 1 : 3;
|
||||
else
|
||||
step = (dot < c3Point) ? 2 : 0;
|
||||
ep1[1] = dp[1] - stops[step];
|
||||
lmask |= step<<2;
|
||||
|
||||
dot = (dp[2] << 4) + (7*ep1[1] + 3*ep2[3] + 5*ep2[2] + ep2[1]);
|
||||
if(dot < halfPoint)
|
||||
step = (dot < c0Point) ? 1 : 3;
|
||||
else
|
||||
step = (dot < c3Point) ? 2 : 0;
|
||||
ep1[2] = dp[2] - stops[step];
|
||||
lmask |= step<<4;
|
||||
|
||||
dot = (dp[3] << 4) + (7*ep1[2] + 5*ep2[3] + ep2[2]);
|
||||
if(dot < halfPoint)
|
||||
step = (dot < c0Point) ? 1 : 3;
|
||||
else
|
||||
step = (dot < c3Point) ? 2 : 0;
|
||||
ep1[3] = dp[3] - stops[step];
|
||||
lmask |= step<<6;
|
||||
|
||||
dp += 4;
|
||||
mask |= lmask << (y*8);
|
||||
{ int *et = ep1; ep1 = ep2; ep2 = et; } // swap
|
||||
}
|
||||
}
|
||||
|
||||
return mask;
|
||||
}
|
||||
|
||||
// The color optimization function. (Clever code, part 1)
|
||||
static void stb__OptimizeColorsBlock(unsigned char *block, unsigned short *pmax16, unsigned short *pmin16)
|
||||
{
|
||||
int mind = 0x7fffffff,maxd = -0x7fffffff;
|
||||
unsigned char *minp, *maxp;
|
||||
double magn;
|
||||
int v_r,v_g,v_b;
|
||||
static const int nIterPower = 4;
|
||||
float covf[6],vfr,vfg,vfb;
|
||||
|
||||
// determine color distribution
|
||||
int cov[6];
|
||||
int mu[3],min[3],max[3];
|
||||
int ch,i,iter;
|
||||
|
||||
for(ch=0;ch<3;ch++)
|
||||
{
|
||||
const unsigned char *bp = ((const unsigned char *) block) + ch;
|
||||
int muv,minv,maxv;
|
||||
|
||||
muv = minv = maxv = bp[0];
|
||||
for(i=4;i<64;i+=4)
|
||||
{
|
||||
muv += bp[i];
|
||||
if (bp[i] < minv) minv = bp[i];
|
||||
else if (bp[i] > maxv) maxv = bp[i];
|
||||
}
|
||||
|
||||
mu[ch] = (muv + 8) >> 4;
|
||||
min[ch] = minv;
|
||||
max[ch] = maxv;
|
||||
}
|
||||
|
||||
// determine covariance matrix
|
||||
for (i=0;i<6;i++)
|
||||
cov[i] = 0;
|
||||
|
||||
for (i=0;i<16;i++)
|
||||
{
|
||||
int r = block[i*4+0] - mu[0];
|
||||
int g = block[i*4+1] - mu[1];
|
||||
int b = block[i*4+2] - mu[2];
|
||||
|
||||
cov[0] += r*r;
|
||||
cov[1] += r*g;
|
||||
cov[2] += r*b;
|
||||
cov[3] += g*g;
|
||||
cov[4] += g*b;
|
||||
cov[5] += b*b;
|
||||
}
|
||||
|
||||
// convert covariance matrix to float, find principal axis via power iter
|
||||
for(i=0;i<6;i++)
|
||||
covf[i] = cov[i] / 255.0f;
|
||||
|
||||
vfr = (float) (max[0] - min[0]);
|
||||
vfg = (float) (max[1] - min[1]);
|
||||
vfb = (float) (max[2] - min[2]);
|
||||
|
||||
for(iter=0;iter<nIterPower;iter++)
|
||||
{
|
||||
float r = vfr*covf[0] + vfg*covf[1] + vfb*covf[2];
|
||||
float g = vfr*covf[1] + vfg*covf[3] + vfb*covf[4];
|
||||
float b = vfr*covf[2] + vfg*covf[4] + vfb*covf[5];
|
||||
|
||||
vfr = r;
|
||||
vfg = g;
|
||||
vfb = b;
|
||||
}
|
||||
|
||||
magn = fabs(vfr);
|
||||
if (fabs(vfg) > magn) magn = fabs(vfg);
|
||||
if (fabs(vfb) > magn) magn = fabs(vfb);
|
||||
|
||||
if(magn < 4.0f) { // too small, default to luminance
|
||||
v_r = 299; // JPEG YCbCr luma coefs, scaled by 1000.
|
||||
v_g = 587;
|
||||
v_b = 114;
|
||||
} else {
|
||||
magn = 512.0 / magn;
|
||||
v_r = (int) (vfr * magn);
|
||||
v_g = (int) (vfg * magn);
|
||||
v_b = (int) (vfb * magn);
|
||||
}
|
||||
|
||||
// Pick colors at extreme points
|
||||
for(i=0;i<16;i++)
|
||||
{
|
||||
int dot = block[i*4+0]*v_r + block[i*4+1]*v_g + block[i*4+2]*v_b;
|
||||
|
||||
if (dot < mind) {
|
||||
mind = dot;
|
||||
minp = block+i*4;
|
||||
}
|
||||
|
||||
if (dot > maxd) {
|
||||
maxd = dot;
|
||||
maxp = block+i*4;
|
||||
}
|
||||
}
|
||||
|
||||
*pmax16 = stb__As16Bit(maxp[0],maxp[1],maxp[2]);
|
||||
*pmin16 = stb__As16Bit(minp[0],minp[1],minp[2]);
|
||||
}
|
||||
|
||||
static int stb__sclamp(float y, int p0, int p1)
|
||||
{
|
||||
int x = (int) y;
|
||||
if (x < p0) return p0;
|
||||
if (x > p1) return p1;
|
||||
return x;
|
||||
}
|
||||
|
||||
// The refinement function. (Clever code, part 2)
|
||||
// Tries to optimize colors to suit block contents better.
|
||||
// (By solving a least squares system via normal equations+Cramer's rule)
|
||||
static int stb__RefineBlock(unsigned char *block, unsigned short *pmax16, unsigned short *pmin16, unsigned int mask)
|
||||
{
|
||||
static const int w1Tab[4] = { 3,0,2,1 };
|
||||
static const int prods[4] = { 0x090000,0x000900,0x040102,0x010402 };
|
||||
// ^some magic to save a lot of multiplies in the accumulating loop...
|
||||
// (precomputed products of weights for least squares system, accumulated inside one 32-bit register)
|
||||
|
||||
float frb,fg;
|
||||
unsigned short oldMin, oldMax, min16, max16;
|
||||
int i, akku = 0, xx,xy,yy;
|
||||
int At1_r,At1_g,At1_b;
|
||||
int At2_r,At2_g,At2_b;
|
||||
unsigned int cm = mask;
|
||||
|
||||
oldMin = *pmin16;
|
||||
oldMax = *pmax16;
|
||||
|
||||
if((mask ^ (mask<<2)) < 4) // all pixels have the same index?
|
||||
{
|
||||
// yes, linear system would be singular; solve using optimal
|
||||
// single-color match on average color
|
||||
int r = 8, g = 8, b = 8;
|
||||
for (i=0;i<16;++i) {
|
||||
r += block[i*4+0];
|
||||
g += block[i*4+1];
|
||||
b += block[i*4+2];
|
||||
}
|
||||
|
||||
r >>= 4; g >>= 4; b >>= 4;
|
||||
|
||||
max16 = (stb__OMatch5[r][0]<<11) | (stb__OMatch6[g][0]<<5) | stb__OMatch5[b][0];
|
||||
min16 = (stb__OMatch5[r][1]<<11) | (stb__OMatch6[g][1]<<5) | stb__OMatch5[b][1];
|
||||
} else {
|
||||
At1_r = At1_g = At1_b = 0;
|
||||
At2_r = At2_g = At2_b = 0;
|
||||
for (i=0;i<16;++i,cm>>=2) {
|
||||
int step = cm&3;
|
||||
int w1 = w1Tab[step];
|
||||
int r = block[i*4+0];
|
||||
int g = block[i*4+1];
|
||||
int b = block[i*4+2];
|
||||
|
||||
akku += prods[step];
|
||||
At1_r += w1*r;
|
||||
At1_g += w1*g;
|
||||
At1_b += w1*b;
|
||||
At2_r += r;
|
||||
At2_g += g;
|
||||
At2_b += b;
|
||||
}
|
||||
|
||||
At2_r = 3*At2_r - At1_r;
|
||||
At2_g = 3*At2_g - At1_g;
|
||||
At2_b = 3*At2_b - At1_b;
|
||||
|
||||
// extract solutions and decide solvability
|
||||
xx = akku >> 16;
|
||||
yy = (akku >> 8) & 0xff;
|
||||
xy = (akku >> 0) & 0xff;
|
||||
|
||||
frb = 3.0f * 31.0f / 255.0f / (xx*yy - xy*xy);
|
||||
fg = frb * 63.0f / 31.0f;
|
||||
|
||||
// solve.
|
||||
max16 = stb__sclamp((At1_r*yy - At2_r*xy)*frb+0.5f,0,31) << 11;
|
||||
max16 |= stb__sclamp((At1_g*yy - At2_g*xy)*fg +0.5f,0,63) << 5;
|
||||
max16 |= stb__sclamp((At1_b*yy - At2_b*xy)*frb+0.5f,0,31) << 0;
|
||||
|
||||
min16 = stb__sclamp((At2_r*xx - At1_r*xy)*frb+0.5f,0,31) << 11;
|
||||
min16 |= stb__sclamp((At2_g*xx - At1_g*xy)*fg +0.5f,0,63) << 5;
|
||||
min16 |= stb__sclamp((At2_b*xx - At1_b*xy)*frb+0.5f,0,31) << 0;
|
||||
}
|
||||
|
||||
*pmin16 = min16;
|
||||
*pmax16 = max16;
|
||||
return oldMin != min16 || oldMax != max16;
|
||||
}
|
||||
|
||||
// Color block compression
|
||||
static void stb__CompressColorBlock(unsigned char *dest, unsigned char *block, int mode)
|
||||
{
|
||||
unsigned int mask;
|
||||
int i;
|
||||
int dither;
|
||||
int refinecount;
|
||||
unsigned short max16, min16;
|
||||
unsigned char dblock[16*4],color[4*4];
|
||||
|
||||
dither = mode & STB_DXT_DITHER;
|
||||
refinecount = (mode & STB_DXT_HIGHQUAL) ? 2 : 1;
|
||||
|
||||
// check if block is constant
|
||||
for (i=1;i<16;i++)
|
||||
if (((unsigned int *) block)[i] != ((unsigned int *) block)[0])
|
||||
break;
|
||||
|
||||
if(i == 16) { // constant color
|
||||
int r = block[0], g = block[1], b = block[2];
|
||||
mask = 0xaaaaaaaa;
|
||||
max16 = (stb__OMatch5[r][0]<<11) | (stb__OMatch6[g][0]<<5) | stb__OMatch5[b][0];
|
||||
min16 = (stb__OMatch5[r][1]<<11) | (stb__OMatch6[g][1]<<5) | stb__OMatch5[b][1];
|
||||
} else {
|
||||
// first step: compute dithered version for PCA if desired
|
||||
if(dither)
|
||||
stb__DitherBlock(dblock,block);
|
||||
|
||||
// second step: pca+map along principal axis
|
||||
stb__OptimizeColorsBlock(dither ? dblock : block,&max16,&min16);
|
||||
if (max16 != min16) {
|
||||
stb__EvalColors(color,max16,min16);
|
||||
mask = stb__MatchColorsBlock(block,color,dither);
|
||||
} else
|
||||
mask = 0;
|
||||
|
||||
// third step: refine (multiple times if requested)
|
||||
for (i=0;i<refinecount;i++) {
|
||||
unsigned int lastmask = mask;
|
||||
|
||||
if (stb__RefineBlock(dither ? dblock : block,&max16,&min16,mask)) {
|
||||
if (max16 != min16) {
|
||||
stb__EvalColors(color,max16,min16);
|
||||
mask = stb__MatchColorsBlock(block,color,dither);
|
||||
} else {
|
||||
mask = 0;
|
||||
break;
|
||||
}
|
||||
}
|
||||
|
||||
if(mask == lastmask)
|
||||
break;
|
||||
}
|
||||
}
|
||||
|
||||
// write the color block
|
||||
if(max16 < min16)
|
||||
{
|
||||
unsigned short t = min16;
|
||||
min16 = max16;
|
||||
max16 = t;
|
||||
mask ^= 0x55555555;
|
||||
}
|
||||
|
||||
dest[0] = (unsigned char) (max16);
|
||||
dest[1] = (unsigned char) (max16 >> 8);
|
||||
dest[2] = (unsigned char) (min16);
|
||||
dest[3] = (unsigned char) (min16 >> 8);
|
||||
dest[4] = (unsigned char) (mask);
|
||||
dest[5] = (unsigned char) (mask >> 8);
|
||||
dest[6] = (unsigned char) (mask >> 16);
|
||||
dest[7] = (unsigned char) (mask >> 24);
|
||||
}
|
||||
|
||||
// Alpha block compression (this is easy for a change)
|
||||
static void stb__CompressAlphaBlock(unsigned char *dest,unsigned char *src,int mode)
|
||||
{
|
||||
int i,dist,bias,dist4,dist2,bits,mask;
|
||||
|
||||
// find min/max color
|
||||
int mn,mx;
|
||||
mn = mx = src[3];
|
||||
|
||||
for (i=1;i<16;i++)
|
||||
{
|
||||
if (src[i*4+3] < mn) mn = src[i*4+3];
|
||||
else if (src[i*4+3] > mx) mx = src[i*4+3];
|
||||
}
|
||||
|
||||
// encode them
|
||||
((unsigned char *)dest)[0] = mx;
|
||||
((unsigned char *)dest)[1] = mn;
|
||||
dest += 2;
|
||||
|
||||
// determine bias and emit color indices
|
||||
// given the choice of mx/mn, these indices are optimal:
|
||||
// http://fgiesen.wordpress.com/2009/12/15/dxt5-alpha-block-index-determination/
|
||||
dist = mx-mn;
|
||||
dist4 = dist*4;
|
||||
dist2 = dist*2;
|
||||
bias = (dist < 8) ? (dist - 1) : (dist/2 + 2);
|
||||
bias -= mn * 7;
|
||||
bits = 0,mask=0;
|
||||
|
||||
for (i=0;i<16;i++) {
|
||||
int a = src[i*4+3]*7 + bias;
|
||||
int ind,t;
|
||||
|
||||
// select index. this is a "linear scale" lerp factor between 0 (val=min) and 7 (val=max).
|
||||
t = (a >= dist4) ? -1 : 0; ind = t & 4; a -= dist4 & t;
|
||||
t = (a >= dist2) ? -1 : 0; ind += t & 2; a -= dist2 & t;
|
||||
ind += (a >= dist);
|
||||
|
||||
// turn linear scale into DXT index (0/1 are extremal pts)
|
||||
ind = -ind & 7;
|
||||
ind ^= (2 > ind);
|
||||
|
||||
// write index
|
||||
mask |= ind << bits;
|
||||
if((bits += 3) >= 8) {
|
||||
*dest++ = mask;
|
||||
mask >>= 8;
|
||||
bits -= 8;
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
static void stb__InitDXT()
|
||||
{
|
||||
int i;
|
||||
for(i=0;i<32;i++)
|
||||
stb__Expand5[i] = (i<<3)|(i>>2);
|
||||
|
||||
for(i=0;i<64;i++)
|
||||
stb__Expand6[i] = (i<<2)|(i>>4);
|
||||
|
||||
for(i=0;i<256+16;i++)
|
||||
{
|
||||
int v = i-8 < 0 ? 0 : i-8 > 255 ? 255 : i-8;
|
||||
stb__QuantRBTab[i] = stb__Expand5[stb__Mul8Bit(v,31)];
|
||||
stb__QuantGTab[i] = stb__Expand6[stb__Mul8Bit(v,63)];
|
||||
}
|
||||
|
||||
stb__PrepareOptTable(&stb__OMatch5[0][0],stb__Expand5,32);
|
||||
stb__PrepareOptTable(&stb__OMatch6[0][0],stb__Expand6,64);
|
||||
}
|
||||
|
||||
void stb_compress_dxt_block(unsigned char *dest, const unsigned char *src, int alpha, int mode)
|
||||
{
|
||||
static int init=1;
|
||||
if (init) {
|
||||
stb__InitDXT();
|
||||
init=0;
|
||||
}
|
||||
|
||||
if (alpha) {
|
||||
stb__CompressAlphaBlock(dest,(unsigned char*) src,mode);
|
||||
dest += 8;
|
||||
}
|
||||
|
||||
stb__CompressColorBlock(dest,(unsigned char*) src,mode);
|
||||
}
|
||||
#endif // STB_DXT_IMPLEMENTATION
|
||||
|
||||
#endif // STB_INCLUDE_STB_DXT_H
|
||||
Loading…
Reference in New Issue
Block a user