C++ TriMesh::from_vertex_handle方法代码示例

Field<T,VertexHandle> gaussian_curvatures(const TriMesh& mesh) {
  // Compute mixed areas
  Field<T,VertexHandle> area(mesh.n_vertices()); // Actually 8*area
  for (const auto f : mesh.face_handles()) {
    const auto v = mesh.vertex_handles(f);
    const TV x0 = mesh.point(v.x),
             x1 = mesh.point(v.y),
             x2 = mesh.point(v.z),
             x01 = x1-x0,
             x12 = x2-x1,
             x20 = x0-x2;
    const T cot0 = cot(x01,x20),
            cot1 = cot(x01,x12),
            cot2 = cot(x12,x20);
    // Compute A_mixed as in Meyer et al.
    if (cot0<=0 && cot1<=0 && cot2<=0) { // Voronoi case
      const T area0 = cot0*sqr_magnitude(x12),
              area1 = cot1*sqr_magnitude(x20),
              area2 = cot2*sqr_magnitude(x01);
      area[v.x] -= (area1+area2);
      area[v.y] -= (area2+area0);
      area[v.z] -= (area0+area1);
    } else { // One of the triangles is obtuse
      const T a = 2*mesh.area(f);
      area[v.x] += (1+(cot0>0))*a;
      area[v.y] += (1+(cot1>0))*a;
      area[v.z] += (1+(cot2>0))*a;
    }
  }
  // Compute curvatures
  Field<T,VertexHandle> K(mesh.n_vertices(),uninit);
  for (const auto v : mesh.vertex_handles()) {
    const TV x = mesh.point(v);
    T sum = 0;
    for (auto e=mesh.cvoh_iter(v);e;++e)
      if (!mesh.is_boundary(e)) {
        const auto v0 = mesh.to_vertex_handle(e),
                   v1 = mesh.from_vertex_handle(mesh.prev_halfedge_handle(e)); 
        sum += angle_between(mesh.point(v0)-x,mesh.point(v1)-x);
      }
    K[v] = 8*((1+!mesh.is_boundary(v))*pi-sum)/area(v);
  }
  return K;
}

void MeshDenoisingViaL0Minimization::calculateAreaBasedEdgeOperator(TriMesh &mesh,
                                                                    std::vector<TriMesh::Point> &area_based_edge_operator,
                                                                    std::vector< std::vector<TriMesh::VertexHandle> > &edge_vertex_handle,
                                                                    std::vector< std::vector<double> > &coef)
{
    std::vector<double> face_area;
    getFaceArea(mesh, face_area);

    area_based_edge_operator.resize((int)mesh.n_edges(), TriMesh::Point(0.0, 0.0, 0.0));
    std::vector<double> temp_coef(4, 0.0);
    coef.resize(mesh.n_edges(), temp_coef);
    std::vector<TriMesh::VertexHandle> vertex_handle(4);
    edge_vertex_handle.resize(mesh.n_edges(), vertex_handle);
    for(TriMesh::EdgeIter e_it = mesh.edges_begin(); e_it != mesh.edges_end(); e_it++)
    {
        if(!mesh.is_boundary(*e_it))
        {
            int index = e_it->idx();
            double edge_length = mesh.calc_edge_length(*e_it);

            // get four vertices correspond to edge *e_it
            TriMesh::HalfedgeHandle he = mesh.halfedge_handle(*e_it, 0);
            TriMesh::VertexHandle v1 = mesh.from_vertex_handle(he);
            TriMesh::VertexHandle v3 = mesh.to_vertex_handle(he);
            TriMesh::HalfedgeHandle he_next = mesh.next_halfedge_handle(he);
            TriMesh::VertexHandle v4 = mesh.to_vertex_handle(he_next);

            TriMesh::HalfedgeHandle he_oppo = mesh.opposite_halfedge_handle(he);
            TriMesh::HalfedgeHandle he_oppo_next = mesh.next_halfedge_handle(he_oppo);
            TriMesh::VertexHandle v2 = mesh.to_vertex_handle(he_oppo_next);

            // two faces
            TriMesh::FaceHandle f1 = mesh.face_handle(he);
            TriMesh::FaceHandle f2 = mesh.face_handle(he_oppo);

            // the area of two faces correspond to edge *e_it
            double area134 = face_area[f1.idx()];
            double area123 = face_area[f2.idx()];
            double totalArea = area123 + area134;

            TriMesh::Point p1 = mesh.point(v1);
            TriMesh::Point p2 = mesh.point(v2);
            TriMesh::Point p3 = mesh.point(v3);
            TriMesh::Point p4 = mesh.point(v4);

            TriMesh::Point p12 = p1 - p2;
            TriMesh::Point p13 = p1 - p3;
            TriMesh::Point p14 = p1 - p4;
            TriMesh::Point p23 = p2 - p3;
            TriMesh::Point p34 = p3 - p4;

            // calc coefficient
            temp_coef[0] = (area123 * (p34 | p13) - area134 * (p13 | p23)) / (edge_length * edge_length * totalArea);
            temp_coef[1] = area134 / totalArea;
            temp_coef[2] = (-area123 * (p13 | p14) - area134 * (p12 | p13)) / (edge_length * edge_length * totalArea);
            temp_coef[3] = area123 / totalArea;
            coef[index] = temp_coef;

            vertex_handle[0] = v1;
            vertex_handle[1] = v2;
            vertex_handle[2] = v3;
            vertex_handle[3] = v4;
            edge_vertex_handle[index] = vertex_handle;

            // calc area-based edge operator
            TriMesh::Point pt = p1 * temp_coef[0] + p2 * temp_coef[1] + p3 * temp_coef[2] + p4 * temp_coef[3];
            area_based_edge_operator[index] = pt;
        }
    }
}