diff options
-rw-r--r-- | source/blender/blenlib/intern/mesh_intersect.cc | 20 |
1 files changed, 18 insertions, 2 deletions
diff --git a/source/blender/blenlib/intern/mesh_intersect.cc b/source/blender/blenlib/intern/mesh_intersect.cc index 526871c7b1f..8276890eec1 100644 --- a/source/blender/blenlib/intern/mesh_intersect.cc +++ b/source/blender/blenlib/intern/mesh_intersect.cc @@ -2225,8 +2225,7 @@ static bool face_is_degenerate(const Face *f) return false; } -/** Fast check for degenerate tris. Only tests for when verts are identical, - * not cases where there are zero-length edges. */ +/** Fast check for degenerate tris. It is OK if it returns true for nearly degenerate triangles. */ static bool any_degenerate_tris_fast(const Array<Face *> triangulation) { for (const Face *f : triangulation) { @@ -2236,6 +2235,23 @@ static bool any_degenerate_tris_fast(const Array<Face *> triangulation) if (v0 == v1 || v0 == v2 || v1 == v2) { return true; } + double3 da = v2->co - v0->co; + double3 db = v2->co - v1->co; + double da_length_squared = da.length_squared(); + double db_length_squared = db.length_squared(); + if (da_length_squared == 0.0 || db_length_squared == 0.0) { + return true; + } + /* |da x db| = |da| |db| sin t, where t is angle between them. + * The triangle is almost degenerate if sin t is almost 0. + * sin^2 t = |da x db|^2 / (|da|^2 |db|^2) + */ + double3 dab = double3::cross_high_precision(da, db); + double dab_length_squared = dab.length_squared(); + double sin_squared_t = dab_length_squared / (da_length_squared * db_length_squared); + if (sin_squared_t < 1e-8) { + return true; + } } return false; } |