surface_mesh_polygonization.h

/********************************************************************
 * Copyright (C) 2015 Liangliang Nan <liangliang.nan@gmail.com>
 * https://3d.bk.tudelft.nl/liangliang/
 *
 * This file is part of Easy3D. If it is useful in your research/work,
 * I would be grateful if you show your appreciation by citing it:
 * ------------------------------------------------------------------
 *      Liangliang Nan.
 *      Easy3D: a lightweight, easy-to-use, and efficient C++ library
 *      for processing and rendering 3D data.
 *      Journal of Open Source Software, 6(64), 3255, 2021.
 * ------------------------------------------------------------------
 *
 * Easy3D is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License Version 3
 * as published by the Free Software Foundation.
 *
 * Easy3D is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 ********************************************************************/
 
#ifndef EASY3D_ALGO_SURFACE_MESH_POLYGONIZATION_H
#define EASY3D_ALGO_SURFACE_MESH_POLYGONIZATION_H
 
#include <easy3d/core/surface_mesh.h>
 
 
namespace easy3d {

    class SurfaceMeshPolygonization {
    public:

        void apply(SurfaceMesh *mesh, float angle_threshold = 1.0f);

        void merge_colinear_edges(SurfaceMesh *mesh, float angle_threshold = 1.0f);
 
    private:
        void internal_apply(SurfaceMesh *mesh, float angle_threshold);
 
        typedef std::vector<SurfaceMesh::Halfedge> Loop;
        std::vector<Loop> extract_boundary_loop(const SurfaceMesh *mesh, int comp_id, std::set<SurfaceMesh::Halfedge>& boundary_edges);
 
        // classify the loops of a planar region into an "outer" loop and several "holes".
        void classify(const SurfaceMesh *mesh, const std::vector<Loop>& loops, Loop& outer, std::vector<Loop>& holes);
 
        // split a complex polygon (with duplicate vertices and possibly hole) into a set of convex polygons
        typedef std::vector<SurfaceMesh::Vertex> Contour;
        std::vector<Contour> split_complex_contour(
                const Contour &outer_poly,              // the outer polygon represented by a list of SurfaceMesh::Vertex
                const std::vector<Contour> &hole_polys, // the holes each represented by a list of SurfaceMesh::Vertex
                const vec3 &normal,                     // the normal of the polygon
                const SurfaceMesh *mesh
        ) const;
 
    private:
        SurfaceMesh::FaceProperty<int> planar_segments_;
    };
 
}
 
#endif  // EASY3D_ALGO_SURFACE_MESH_POLYGONIZATION_H