Update stb_truetype.h

src/external/stb_truetype.h

@@ -54,7 +54,7 @@
 //       Hou Qiming                 Derek Vinyard
 //       Rob Loach                  Cort Stratton
 //       Kenney Phillis Jr.         Brian Costabile
-//       Ken Voskuil (kaesve)
+//       Ken Voskuil (kaesve)       Yakov Galka
 //
 // VERSION HISTORY
 //
@@ -4604,6 +4604,8 @@ STBTT_DEF unsigned char * stbtt_GetGlyphSDF(const stbtt_fontinfo *info, float sc
    scale_y = -scale_y;
 
    {
+      // distance from singular values (in the same units as the pixel grid)
+      const float eps = 1./1024, eps2 = eps*eps;
       int x,y,i,j;
       float *precompute;
       stbtt_vertex *verts;
@@ -4616,15 +4618,15 @@ STBTT_DEF unsigned char * stbtt_GetGlyphSDF(const stbtt_fontinfo *info, float sc
             float x0 = verts[i].x*scale_x, y0 = verts[i].y*scale_y;
             float x1 = verts[j].x*scale_x, y1 = verts[j].y*scale_y;
             float dist = (float) STBTT_sqrt((x1-x0)*(x1-x0) + (y1-y0)*(y1-y0));
-            precompute[i] = (dist == 0) ? 0.0f : 1.0f / dist;
+            precompute[i] = (dist < eps) ? 0.0f : 1.0f / dist;
          } else if (verts[i].type == STBTT_vcurve) {
             float x2 = verts[j].x *scale_x, y2 = verts[j].y *scale_y;
             float x1 = verts[i].cx*scale_x, y1 = verts[i].cy*scale_y;
             float x0 = verts[i].x *scale_x, y0 = verts[i].y *scale_y;
             float bx = x0 - 2*x1 + x2, by = y0 - 2*y1 + y2;
             float len2 = bx*bx + by*by;
-            if (len2 != 0.0f)
-               precompute[i] = 1.0f / p">(bx*bx + by*by);
+            if (len2 >= eps2)
+               precompute[i] = 1.0f / n">len2;
             else
                precompute[i] = 0.0f;
          } else
@@ -4689,8 +4691,8 @@ STBTT_DEF unsigned char * stbtt_GetGlyphSDF(const stbtt_fontinfo *info, float sc
                         float a = 3*(ax*bx + ay*by);
                         float b = 2*(ax*ax + ay*ay) + (mx*bx+my*by);
                         float c = mx*ax+my*ay;
-                        if (a == 0.0) { // if a is 0, it's linear
-                           if (b != 0.0) {
+                        if (STBTT_fabs(a) < eps2) { // if a is 0, it's linear
+                           if (STBTT_fabs(b) >= eps2) {
                               res[num++] = -c/b;
                            }
                         } else {