Mesh::leftTangent

MeshInspector · Jan 5, 2025 · b88eb0a · b88eb0a
1 parent c5a84c9
commit b88eb0a
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Showing 2 changed files with 11 additions and 0 deletions.
diff --git a/source/MRMesh/MRMesh.cpp b/source/MRMesh/MRMesh.cpp
@@ -488,6 +488,14 @@ Vector3d Mesh::holeDirArea( EdgeId e0 ) const
     return 0.5 * sum;
 }
 
+Vector3f Mesh::leftTangent( EdgeId e ) const
+{
+    assert( topology.left( e ) );
+    const auto lNorm = leftNormal( e );
+    const auto eDir = edgeVector( e ).normalized();
+    return cross( lNorm, eDir );
+}
+
 Vector3f Mesh::dirDblArea( VertId v ) const
 {
     Vector3f sum;

diff --git a/source/MRMesh/MRMesh.h b/source/MRMesh/MRMesh.h
@@ -186,6 +186,9 @@ struct [[nodiscard]] Mesh
     /// if the hole is planar then returned vector is orthogonal to the plane pointing outside and its magnitude is equal to hole area
     [[nodiscard]] MRMESH_API Vector3d holeDirArea( EdgeId e ) const;
 
+    /// computes unit vector that is both orthogonal to given edge and to the normal of its left triangle, the vector is directed inside left triangle
+    [[nodiscard]] MRMESH_API Vector3f leftTangent( EdgeId e ) const;
+
     /// computes triangular face normal from its vertices
     [[nodiscard]] Vector3f leftNormal( EdgeId e ) const { return leftDirDblArea( e ).normalized(); }