Method compute_from_mesh

src/Attributes/VertexLaplacianAttribute.cpp:9–33

using namespace PyMesh;

void VertexLaplacianAttribute::compute_from_mesh(Mesh& mesh) {
    const size_t dim = mesh.get_dim();
    const size_t num_vertices = mesh.get_num_vertices();
    const size_t num_faces = mesh.get_num_faces();
    const size_t vertex_per_face = mesh.get_vertex_per_face();

    if (vertex_per_face != 3) {
        throw NotImplementedError(
                "Only triangle Laplacian is supported for now.");
    }

    VectorF& laplacian = m_values;
    laplacian = VectorF::Zero(num_vertices * dim);
    for (size_t i=0; i<num_faces; i++) {
        VectorI face = mesh.get_face(i);
        VectorF v0 = mesh.get_vertex(face[0]);
        VectorF v1 = mesh.get_vertex(face[1]);
        VectorF v2 = mesh.get_vertex(face[2]);
        assert(face.size() == vertex_per_face);
        VectorF cotan_weights = compute_cotan_weights(v0, v1, v2);
        laplacian.segment(dim*face[0], dim) += cotan_weights[2] * (v0-v1) + cotan_weights[1] * (v0-v2);
        laplacian.segment(dim*face[1], dim) += cotan_weights[0] * (v1-v2) + cotan_weights[2] * (v1-v0);
        laplacian.segment(dim*face[2], dim) += cotan_weights[1] * (v2-v0) + cotan_weights[0] * (v2-v1);
    }
}

VectorF VertexLaplacianAttribute::compute_cotan_weights(
        const VectorF& v0, const VectorF& v1, const VectorF& v2) {