Commit 49e7bb6a authored by Jakub Klinkovský's avatar Jakub Klinkovský
Browse files

Optimized getTriangleArea for 3D

parent 2734b3b6

src/TNL/Meshes/Geometry/getEntityMeasure.h

+4 −8
Original line number Diff line number Diff line
@@ -99,14 +99,10 @@ getTriangleArea( const VectorExpression & v1, 
{

    using Real = typename VectorExpression::RealType;

    // formula from http://math.stackexchange.com/a/128999

    Real S = 0.0;

    Real aux = v1.y() * v2.z() - v1.z() * v2.y();   // first component of the cross product

    S += aux * aux;

    aux = v1.z() * v2.x() - v1.x() * v2.z();        // second component of the cross product

    S += aux * aux;

    aux = v1.x() * v2.y() - v1.y() * v2.x();        // third component of the cross product

    S += aux * aux;

    return 0.5 * ::sqrt( S );

    const Real c1 = v1.y() * v2.z() - v1.z() * v2.y();   // first component of the cross product

    const Real c2 = v1.z() * v2.x() - v1.x() * v2.z();   // second component of the cross product

    const Real c3 = v1.x() * v2.y() - v1.y() * v2.x();   // third component of the cross product

    return 0.5 * TNL::sqrt( c1 * c1 + c2 * c2 + c3 * c3 );

}



template< typename MeshConfig, typename Device >