Disable tolerance in Orient2d collinearity test

This fixes failures for me when trying to triangulate concave-by-less-than-epsilon boundary polylines.
brandon-kohn · Mar 16, 2022 · 57b3039 · 57b3039
1 parent 8b5fa15
commit 57b3039
Showing 1 changed file with 4 additions and 1 deletion.
diff --git a/poly2tri/common/utils.h b/poly2tri/common/utils.h
@@ -68,7 +68,10 @@ Orientation Orient2d(const Point& pa, const Point& pb, const Point& pc)
   double detleft = (pa.x - pc.x) * (pb.y - pc.y);
   double detright = (pa.y - pc.y) * (pb.x - pc.x);
   double val = detleft - detright;
-  if (val > -EPSILON && val < EPSILON) {
+
+// Using a tolerance here fails on concave-by-subepsilon boundaries
+//   if (val > -EPSILON && val < EPSILON) {
+  if (val == 0) {
     return COLLINEAR;
   } else if (val > 0) {
     return CCW;