/// <summary>
/// computes sum of opening-angles in triangles around vid, minus 2pi.
/// This is zero on flat areas.
/// </summary>
public static double DiscreteGaussCurvature(DMesh3 mesh, int vid)
{
double angle_sum = 0;
foreach (int tid in mesh.VtxTrianglesItr(vid))
{
Index3i et = mesh.GetTriangle(tid);
int idx = IndexUtil.find_tri_index(vid, ref et);
angle_sum += mesh.GetTriInternalAngleR(tid, idx);
}
return(angle_sum - MathUtil.TwoPI);
}
