nanosvg: Fix drawing artefacts due to rounding errors: memononen/nano…

…svg#247
tcltk · Oct 23, 2023 · d8c34d6 · d8c34d6
1 parent 22b0521
commit d8c34d6
Showing 1 changed file with 9 additions and 3 deletions.
diff --git a/generic/nanosvgrast.h b/generic/nanosvgrast.h
@@ -886,11 +886,17 @@ static NSVGactiveEdge* nsvg__addActive(NSVGrasterizer* r, NSVGedge* e, float sta
 	dxdy = (e->x1 - e->x0) / (e->y1 - e->y0);
 /*	STBTT_assert(e->y0 <= start_point); */
 	/* round dx down to avoid going too far */
+	/*
+	 * HaO 2023-10-23
+	 * pull request
+	 * https://github.com/memononen/nanosvg/pull/247
+	 * replaces floorf by roundf in the following 3 lines
+	 */
 	if (dxdy < 0)
-		z->dx = (int)(-floorf(NSVG__FIX * -dxdy));
+		z->dx = (int)(-roundf(NSVG__FIX * -dxdy));
 	else
-		z->dx = (int)floorf(NSVG__FIX * dxdy);
-	z->x = (int)floorf(NSVG__FIX * (e->x0 + dxdy * (startPoint - e->y0)));
+		z->dx = (int)roundf(NSVG__FIX * dxdy);
+	z->x = (int)roundf(NSVG__FIX * (e->x0 + dxdy * (startPoint - e->y0)));
 /*	z->x -= off_x * FIX; */
 	z->ey = e->y1;
 	z->next = 0;