【CGAL_网格处理】法向量计算

文档阅读

在CGAL网格处理包中法向量计算部分，共提供如下5个函数：

  • CGAL::Polygon_mesh_processing::compute_face_normal()

  • CGAL::Polygon_mesh_processing::compute_vertex_normal()

  • CGAL::Polygon_mesh_processing::compute_face_normals()

  • CGAL::Polygon_mesh_processing::compute_vertex_normals()

  • CGAL::Polygon_mesh_processing::compute_normals().

其中，前两个分别计算单个面和顶点的法向量，第三第四个分别计算网格所有的面和顶点的法向量，最后一个同时计算网格所有面和顶点的法向量。

被计算得到的法向量将以属性图的形式进行记录。

代码测试

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
#include <CGAL/Exact_predicates_inexact_constructions_kernel.h>
#include <CGAL/Surface_mesh.h>
#include <CGAL/Polygon_mesh_processing/compute_normal.h>
#include <CGAL/Polygon_mesh_processing/IO/polygon_mesh_io.h>
#include <fstream>
#include <iostream>
typedef CGAL::Exact_predicates_inexact_constructions_kernel       K;
typedef K::Point_3                                                Point;
typedef K::Vector_3                                               Vector;
typedef CGAL::Surface_mesh<Point>                                 Surface_mesh;
typedef boost::graph_traits<Surface_mesh>::vertex_descriptor      vertex_descriptor;
typedef boost::graph_traits<Surface_mesh>::face_descriptor        face_descriptor;
namespace PMP = CGAL::Polygon_mesh_processing;
int main(int argc, char* argv[])
{
  const std::string filename = (argc > 1) ? argv[1] : CGAL::data_file_path("meshes/eight.off");
  Surface_mesh mesh;
  if(!PMP::IO::read_polygon_mesh(filename, mesh))
  {
    std::cerr << "Invalid input." << std::endl;
    return 1;
  }
  auto vnormals = mesh.add_property_map<vertex_descriptor, Vector>("v:normals", CGAL::NULL_VECTOR).first;
  auto fnormals = mesh.add_property_map<face_descriptor, Vector>("f:normals", CGAL::NULL_VECTOR).first;
  PMP::compute_normals(mesh, vnormals, fnormals);
  std::cout << "Vertex normals :" << std::endl;
  for(vertex_descriptor vd: vertices(mesh))
    std::cout << vnormals[vd] << std::endl;
  std::cout << "Face normals :" << std::endl;
  for(face_descriptor fd: faces(mesh))
    std::cout << fnormals[fd] << std::endl;
  return 0;
}

VTK可视化法向量