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diff --git a/thirdparty/stb/stb_dxt.h b/thirdparty/stb/stb_dxt.h
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+// stb_dxt.h - v1.08b - DXT1/DXT5 compressor - public domain
+// original by fabian "ryg" giesen - ported to C by stb
+// use '#define STB_DXT_IMPLEMENTATION' before including to create the implementation
+//
+// USAGE:
+//   call stb_compress_dxt_block() for every block (you must pad)
+//     source should be a 4x4 block of RGBA data in row-major order;
+//     A is ignored if you specify alpha=0; you can turn on dithering
+//     and "high quality" using mode.
+//
+// version history:
+//   v1.08  - (sbt) fix bug in dxt-with-alpha block
+//   v1.07  - (stb) bc4; allow not using libc; add STB_DXT_STATIC
+//   v1.06  - (stb) fix to known-broken 1.05
+//   v1.05  - (stb) support bc5/3dc (Arvids Kokins), use extern "C" in C++ (Pavel Krajcevski)
+//   v1.04  - (ryg) default to no rounding bias for lerped colors (as per S3TC/DX10 spec);
+//            single color match fix (allow for inexact color interpolation);
+//            optimal DXT5 index finder; "high quality" mode that runs multiple refinement steps.
+//   v1.03  - (stb) endianness support
+//   v1.02  - (stb) fix alpha encoding bug
+//   v1.01  - (stb) fix bug converting to RGB that messed up quality, thanks ryg & cbloom
+//   v1.00  - (stb) first release
+//
+// contributors: 
+//   Kevin Schmidt (#defines for "freestanding" compilation)
+//   github:ppiastucki (BC4 support)
+// 
+// LICENSE
+//
+//   See end of file for license information.
+
+#ifndef STB_INCLUDE_STB_DXT_H
+#define STB_INCLUDE_STB_DXT_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#ifdef STB_DXT_STATIC
+#define STBDDEF static
+#else
+#define STBDDEF extern
+#endif
+
+// compression mode (bitflags)
+#define STB_DXT_NORMAL    0
+#define STB_DXT_DITHER    1   // use dithering. dubious win. never use for normal maps and the like!
+#define STB_DXT_HIGHQUAL  2   // high quality mode, does two refinement steps instead of 1. ~30-40% slower.
+
+STBDDEF void stb_compress_dxt_block(unsigned char *dest, const unsigned char *src_rgba_four_bytes_per_pixel, int alpha, int mode);
+STBDDEF void stb_compress_bc4_block(unsigned char *dest, const unsigned char *src_r_one_byte_per_pixel);
+STBDDEF void stb_compress_bc5_block(unsigned char *dest, const unsigned char *src_rg_two_byte_per_pixel);
+
+#define STB_COMPRESS_DXT_BLOCK
+
+#ifdef __cplusplus
+}
+#endif
+#endif // STB_INCLUDE_STB_DXT_H
+
+#ifdef STB_DXT_IMPLEMENTATION
+
+// configuration options for DXT encoder. set them in the project/makefile or just define
+// them at the top.
+
+// STB_DXT_USE_ROUNDING_BIAS
+//     use a rounding bias during color interpolation. this is closer to what "ideal"
+//     interpolation would do but doesn't match the S3TC/DX10 spec. old versions (pre-1.03)
+//     implicitly had this turned on. 
+//
+//     in case you're targeting a specific type of hardware (e.g. console programmers):
+//     NVidia and Intel GPUs (as of 2010) as well as DX9 ref use DXT decoders that are closer
+//     to STB_DXT_USE_ROUNDING_BIAS. AMD/ATI, S3 and DX10 ref are closer to rounding with no bias.
+//     you also see "(a*5 + b*3) / 8" on some old GPU designs.
+// #define STB_DXT_USE_ROUNDING_BIAS
+
+#include <stdlib.h>
+
+#if !defined(STBD_ABS) || !defined(STBI_FABS)
+#include <math.h>
+#endif
+
+#ifndef STBD_ABS
+#define STBD_ABS(i)           abs(i)
+#endif
+
+#ifndef STBD_FABS
+#define STBD_FABS(x)          fabs(x)
+#endif
+
+#ifndef STBD_MEMSET
+#include <string.h>
+#define STBD_MEMSET           memset
+#endif
+
+static unsigned char stb__Expand5[32];
+static unsigned char stb__Expand6[64];
+static unsigned char stb__OMatch5[256][2];
+static unsigned char stb__OMatch6[256][2];
+static unsigned char stb__QuantRBTab[256+16];
+static unsigned char stb__QuantGTab[256+16];
+
+static int stb__Mul8Bit(int a, int b)
+{
+  int t = a*b + 128;
+  return (t + (t >> 8)) >> 8;
+}
+
+static void stb__From16Bit(unsigned char *out, unsigned short v)
+{
+   int rv = (v & 0xf800) >> 11;
+   int gv = (v & 0x07e0) >>  5;
+   int bv = (v & 0x001f) >>  0;
+
+   out[0] = stb__Expand5[rv];
+   out[1] = stb__Expand6[gv];
+   out[2] = stb__Expand5[bv];
+   out[3] = 0;
+}
+
+static unsigned short stb__As16Bit(int r, int g, int b)
+{
+   return (stb__Mul8Bit(r,31) << 11) + (stb__Mul8Bit(g,63) << 5) + stb__Mul8Bit(b,31);
+}
+
+// linear interpolation at 1/3 point between a and b, using desired rounding type
+static int stb__Lerp13(int a, int b)
+{
+#ifdef STB_DXT_USE_ROUNDING_BIAS
+   // with rounding bias
+   return a + stb__Mul8Bit(b-a, 0x55);
+#else
+   // without rounding bias
+   // replace "/ 3" by "* 0xaaab) >> 17" if your compiler sucks or you really need every ounce of speed.
+   return (2*a + b) / 3;
+#endif
+}
+
+// lerp RGB color
+static void stb__Lerp13RGB(unsigned char *out, unsigned char *p1, unsigned char *p2)
+{
+   out[0] = stb__Lerp13(p1[0], p2[0]);
+   out[1] = stb__Lerp13(p1[1], p2[1]);
+   out[2] = stb__Lerp13(p1[2], p2[2]);
+}
+
+/****************************************************************************/
+
+// compute table to reproduce constant colors as accurately as possible
+static void stb__PrepareOptTable(unsigned char *Table,const unsigned char *expand,int size)
+{
+   int i,mn,mx;
+   for (i=0;i<256;i++) {
+      int bestErr = 256;
+      for (mn=0;mn<size;mn++) {
+         for (mx=0;mx<size;mx++) {
+            int mine = expand[mn];
+            int maxe = expand[mx];
+            int err = STBD_ABS(stb__Lerp13(maxe, mine) - i);
+            
+            // DX10 spec says that interpolation must be within 3% of "correct" result,
+            // add this as error term. (normally we'd expect a random distribution of
+            // +-1.5% error, but nowhere in the spec does it say that the error has to be
+            // unbiased - better safe than sorry).
+            err += STBD_ABS(maxe - mine) * 3 / 100;
+            
+            if(err < bestErr)
+            { 
+               Table[i*2+0] = mx;
+               Table[i*2+1] = mn;
+               bestErr = err;
+            }
+         }
+      }
+   }
+}
+
+static void stb__EvalColors(unsigned char *color,unsigned short c0,unsigned short c1)
+{
+   stb__From16Bit(color+ 0, c0);
+   stb__From16Bit(color+ 4, c1);
+   stb__Lerp13RGB(color+ 8, color+0, color+4);
+   stb__Lerp13RGB(color+12, color+4, color+0);
+}
+
+// Block dithering function. Simply dithers a block to 565 RGB.
+// (Floyd-Steinberg)
+static void stb__DitherBlock(unsigned char *dest, unsigned char *block)
+{
+  int err[8],*ep1 = err,*ep2 = err+4, *et;
+  int ch,y;
+
+  // process channels seperately
+  for (ch=0; ch<3; ++ch) {
+      unsigned char *bp = block+ch, *dp = dest+ch;
+      unsigned char *quant = (ch == 1) ? stb__QuantGTab+8 : stb__QuantRBTab+8;
+      STBD_MEMSET(err, 0, sizeof(err));
+      for(y=0; y<4; ++y) {
+         dp[ 0] = quant[bp[ 0] + ((3*ep2[1] + 5*ep2[0]) >> 4)];
+         ep1[0] = bp[ 0] - dp[ 0];
+         dp[ 4] = quant[bp[ 4] + ((7*ep1[0] + 3*ep2[2] + 5*ep2[1] + ep2[0]) >> 4)];
+         ep1[1] = bp[ 4] - dp[ 4];
+         dp[ 8] = quant[bp[ 8] + ((7*ep1[1] + 3*ep2[3] + 5*ep2[2] + ep2[1]) >> 4)];
+         ep1[2] = bp[ 8] - dp[ 8];
+         dp[12] = quant[bp[12] + ((7*ep1[2] + 5*ep2[3] + ep2[2]) >> 4)];
+         ep1[3] = bp[12] - dp[12];
+         bp += 16;
+         dp += 16;
+         et = ep1, ep1 = ep2, ep2 = et; // swap
+      }
+   }
+}
+
+// The color matching function
+static unsigned int stb__MatchColorsBlock(unsigned char *block, unsigned char *color,int dither)
+{
+   unsigned int mask = 0;
+   int dirr = color[0*4+0] - color[1*4+0];
+   int dirg = color[0*4+1] - color[1*4+1];
+   int dirb = color[0*4+2] - color[1*4+2];
+   int dots[16];
+   int stops[4];
+   int i;
+   int c0Point, halfPoint, c3Point;
+
+   for(i=0;i<16;i++)
+      dots[i] = block[i*4+0]*dirr + block[i*4+1]*dirg + block[i*4+2]*dirb;
+
+   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 = STBD_FABS(vfr);
+  if (STBD_FABS(vfg) > magn) magn = STBD_FABS(vfg);
+  if (STBD_FABS(vfb) > magn) magn = STBD_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 stride)
+{
+   int i,dist,bias,dist4,dist2,bits,mask;
+
+   // find min/max color
+   int mn,mx;
+   mn = mx = src[0];
+
+   for (i=1;i<16;i++)
+   {
+      if (src[i*stride] < mn) mn = src[i*stride];
+      else if (src[i*stride] > mx) mx = src[i*stride];
+   }
+
+   // 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*stride]*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)
+{
+   unsigned char data[16][4];
+   static int init=1;
+   if (init) {
+      stb__InitDXT();
+      init=0;
+   }
+
+   if (alpha) {
+      int i;
+      stb__CompressAlphaBlock(dest,(unsigned char*) src+3, 4);
+      dest += 8;
+      // make a new copy of the data in which alpha is opaque,
+      // because code uses a fast test for color constancy
+      memcpy(data, src, 4*16);
+      for (i=0; i < 16; ++i)
+         data[i][3] = 255;
+      src = &data[0][0];
+   }
+
+   stb__CompressColorBlock(dest,(unsigned char*) src,mode);
+}
+
+void stb_compress_bc4_block(unsigned char *dest, const unsigned char *src)
+{
+   stb__CompressAlphaBlock(dest,(unsigned char*) src, 1);
+}
+
+void stb_compress_bc5_block(unsigned char *dest, const unsigned char *src)
+{
+   stb__CompressAlphaBlock(dest,(unsigned char*) src,2);
+   stb__CompressAlphaBlock(dest + 8,(unsigned char*) src+1,2);
+}
+#endif // STB_DXT_IMPLEMENTATION
+
+/*
+------------------------------------------------------------------------------
+This software is available under 2 licenses -- choose whichever you prefer.
+------------------------------------------------------------------------------
+ALTERNATIVE A - MIT License
+Copyright (c) 2017 Sean Barrett
+Permission is hereby granted, free of charge, to any person obtaining a copy of 
+this software and associated documentation files (the "Software"), to deal in 
+the Software without restriction, including without limitation the rights to 
+use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies 
+of the Software, and to permit persons to whom the Software is furnished to do 
+so, subject to the following conditions:
+The above copyright notice and this permission notice shall be included in all 
+copies or substantial portions of the Software.
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE 
+SOFTWARE.
+------------------------------------------------------------------------------
+ALTERNATIVE B - Public Domain (www.unlicense.org)
+This is free and unencumbered software released into the public domain.
+Anyone is free to copy, modify, publish, use, compile, sell, or distribute this 
+software, either in source code form or as a compiled binary, for any purpose, 
+commercial or non-commercial, and by any means.
+In jurisdictions that recognize copyright laws, the author or authors of this 
+software dedicate any and all copyright interest in the software to the public 
+domain. We make this dedication for the benefit of the public at large and to 
+the detriment of our heirs and successors. We intend this dedication to be an 
+overt act of relinquishment in perpetuity of all present and future rights to 
+this software under copyright law.
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 
+AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN 
+ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION 
+WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+------------------------------------------------------------------------------
+*/