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Fix adapt crash for mixed-element 2D meshes with frozen quad layers #524

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Merged
joshia5 merged 2 commits into from
Dec 16, 2025
Merged

Fix adapt crash for mixed-element 2D meshes with frozen quad layers #524

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996cf39
pumi adapt would crash for mixed element meshes with frozen quad laye…
como2099 Dec 15, 2025
08d787b
Make quad validity check coordinate system-independent and numericall…
como2099 Dec 16, 2025
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26 changes: 26 additions & 0 deletions ma/maQuality.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -569,6 +569,32 @@ bool isLayerElementOk(Mesh* m, Entity* e)
return isPyramidOk(m, e);
if (type == apf::Mesh::PRISM)
return isPrismOk(m, e);
if (type == apf::Mesh::QUAD) {
// Check if quad is non-degenerate without assuming a specific embedding.
// The quad is considered valid if its two sub-triangles have non-zero area
// and consistent orientation.

Entity* v[4];
m->getDownward(e, 0, v);
Vector p[4];
for (int i = 0; i < 4; ++i)
m->getPoint(v[i], 0, p[i]);

// Form two triangles sharing a diagonal
Vector n1 = apf::cross(p[1] - p[0], p[2] - p[0]);
Vector n2 = apf::cross(p[2] - p[0], p[3] - p[0]);

double a1 = n1.getLength();
double a2 = n2.getLength();

// Reject degenerate triangles
const double eps = 1e-14;
if (a1 < eps || a2 < eps)
return false;

// Check consistent orientation (normals point in the same general direction)
return (n1 * n2) > eps * a1 * a2;
}
abort();
return false;
}
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