Fix polygon triangulation failure.

The ear clipping algorithm used to triangulate polygons has a slightly too conservative point-in-triangle test which can, in some configurations prevent it from finding a possible tessellation. Relaxing the test by considering that points exactly on edges don't belong the triangle fixes the issue. Changing the semantic of the test is safe because no other code makes use of it. A more detailed explanation can be found in issue #16395.

Fixes #16395.

(cherry picked from commit 91215e1919)
This commit is contained in:
Nicolas Silva 2018-02-05 16:01:24 +01:00 committed by Hein-Pieter van Braam
parent 82b9a13e0c
commit a0e59a7259
1 changed files with 1 additions and 1 deletions

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@ -74,7 +74,7 @@ bool Triangulate::is_inside_triangle(real_t Ax, real_t Ay,
cCROSSap = cx * apy - cy * apx;
bCROSScp = bx * cpy - by * cpx;
return ((aCROSSbp >= 0.0) && (bCROSScp >= 0.0) && (cCROSSap >= 0.0));
return ((aCROSSbp > 0.0) && (bCROSScp > 0.0) && (cCROSSap > 0.0));
};
bool Triangulate::snip(const Vector<Vector2> &p_contour, int u, int v, int w, int n, const Vector<int> &V) {