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stb_truetype -- fix floating point comparison against zero by using a correct epsilon

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yakov 2021-03-23 00:33:05 -04:00
parent b42009b3b9
commit 7e2ade58ea
1 changed files with 8 additions and 5 deletions
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13
stb_truetype.h
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@ -4547,6 +4547,9 @@ STBTT_DEF unsigned char * stbtt_GetGlyphSDF(const stbtt_fontinfo *info, float sc
// invert for y-downwards bitmaps // invert for y-downwards bitmaps
scale_y = -scale_y; scale_y = -scale_y;
// distance from singular values (in the same units as the pixel grid)
const float eps = 1./128, eps2 = eps*eps;
{ {
int x,y,i,j; int x,y,i,j;
float *precompute; float *precompute;
@ -4560,15 +4563,15 @@ 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 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 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)); 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) { } else if (verts[i].type == STBTT_vcurve) {
float x2 = verts[j].x *scale_x, y2 = verts[j].y *scale_y; 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 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 x0 = verts[i].x *scale_x, y0 = verts[i].y *scale_y;
float bx = x0 - 2*x1 + x2, by = y0 - 2*y1 + y2; float bx = x0 - 2*x1 + x2, by = y0 - 2*y1 + y2;
float len2 = bx*bx + by*by; float len2 = bx*bx + by*by;
if (len2 != 0.0f) if (len2 >= eps2)
precompute[i] = 1.0f / (bx*bx + by*by); precompute[i] = 1.0f / len2;
else else
precompute[i] = 0.0f; precompute[i] = 0.0f;
} else } else
@ -4633,8 +4636,8 @@ STBTT_DEF unsigned char * stbtt_GetGlyphSDF(const stbtt_fontinfo *info, float sc
float a = 3*(ax*bx + ay*by); float a = 3*(ax*bx + ay*by);
float b = 2*(ax*ax + ay*ay) + (mx*bx+my*by); float b = 2*(ax*ax + ay*ay) + (mx*bx+my*by);
float c = mx*ax+my*ay; float c = mx*ax+my*ay;
if (a == 0.0) { // if a is 0, it's linear if (fabs(a) < eps2) { // if a is 0, it's linear
if (b != 0.0) { if (fabs(b) >= eps2) {
res[num++] = -c/b; res[num++] = -c/b;
} }
} else { } else {