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#ifndef __MANIFOLD_H
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#ifndef __MANIFOLD_H
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#define __MANIFOLD_H
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#define __MANIFOLD_H
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#include <vector>
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#include <vector>
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#include <list>
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#include <list>
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#include <map>
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#include <map>
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#include "Vertex.h"
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#include "Vertex.h"
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#include "HalfEdge.h"
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#include "HalfEdge.h"
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#include "Face.h"
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#include "Face.h"
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namespace HMesh
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namespace HMesh
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{
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{
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class VertexCirculator;
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class VertexCirculator;
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class FaceCirculator;
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class FaceCirculator;
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/** \brief A Data structure representing an open or closed manifold.
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/** \brief A Data structure representing an open or closed manifold.
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Manifold keeps lists of the entities making up a halfedge mesh
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Manifold keeps lists of the entities making up a halfedge mesh
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and provides basic functions for creating new faces, halfedges
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and provides basic functions for creating new faces, halfedges
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and vertices. There are also primitive operations for editing
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and vertices. There are also primitive operations for editing
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such as edge collapse. */
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such as edge collapse. */
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struct Manifold
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struct Manifold
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{
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{
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std::list<Vertex> vertex_db;
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std::list<Vertex> vertex_db;
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std::list<Face> face_db;
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std::list<Face> face_db;
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std::list<HalfEdge> halfedge_db;
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std::list<HalfEdge> halfedge_db;
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/** Remove a face if it contains only two edges.
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/** Remove a face if it contains only two edges.
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This is an auxiliary function called from collapse_halfedge. */
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This is an auxiliary function called from collapse_halfedge. */
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void remove_face_if_degenerate(HalfEdgeIter fi);
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void remove_face_if_degenerate(HalfEdgeIter fi);
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/** Empty copy constructor.
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/** Empty copy constructor.
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Copying a manifold will not work, since faces, vertices, and
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Copying a manifold will not work, since faces, vertices, and
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halfedges contain iterators pointing to other faces, vertices,
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halfedges contain iterators pointing to other faces, vertices,
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and halfedges. These pointers would need to be changed if the
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and halfedges. These pointers would need to be changed if the
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mesh were copied. In other words, we would need to walk the
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mesh were copied. In other words, we would need to walk the
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entire mesh. This may be required but it should not be an
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entire mesh. This may be required but it should not be an
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operation that is easily invoked by calling the copy constructor.
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operation that is easily invoked by calling the copy constructor.
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Hence, this operator is made private. */
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Hence, this operator is made private. */
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Manifold(const Manifold& m2) {}
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Manifold(const Manifold& m2) {}
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/** Empty assignment operator.
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/** Empty assignment operator.
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The assignment operator is private for the same reason that the
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The assignment operator is private for the same reason that the
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copy constructor is private. */
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copy constructor is private. */
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const Manifold& operator=(const Manifold& m2) {}
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const Manifold& operator=(const Manifold& m2) {}
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public:
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public:
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/// Construct an empty manifold.
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/// Construct an empty manifold.
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Manifold() {}
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Manifold() {}
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/// Return the bounding box of the manifold.
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/// Return the bounding box of the manifold.
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void get_bbox(CGLA::Vec3f&, CGLA::Vec3f&);
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void get_bbox(CGLA::Vec3f&, CGLA::Vec3f&);
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/// Get a bounding sphere
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/// Get a bounding sphere
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void get_bsphere(CGLA::Vec3f& c, float& r);
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void get_bsphere(CGLA::Vec3f& c, float& r);
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/// Clear the manifold - removing all data.
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/// Clear the manifold - removing all data.
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void clear()
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void clear()
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{
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{
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vertex_db.clear();
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vertex_db.clear();
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face_db.clear();
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face_db.clear();
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halfedge_db.clear();
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halfedge_db.clear();
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}
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}
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/// Return the number of faces.
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/// Return the number of faces.
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int no_faces() const {return face_db.size();}
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int no_faces() const {return face_db.size();}
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/// Return the number of halfedges.
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/// Return the number of halfedges.
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int no_halfedges() const {return halfedge_db.size();}
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int no_halfedges() const {return halfedge_db.size();}
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/// Return the number of vertices
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/// Return the number of vertices
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int no_vertices() const {return vertex_db.size();}
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int no_vertices() const {return vertex_db.size();}
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/// Create a new vertex at a given position.
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/// Create a new vertex at a given position.
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VertexIter create_vertex(const CGLA::Vec3f& pos)
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VertexIter create_vertex(const CGLA::Vec3f& pos)
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{
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{
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vertex_db.push_back(Vertex(pos));
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vertex_db.push_back(Vertex(pos));
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return --vertex_db.end();
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return --vertex_db.end();
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}
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}
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/// Create a new face
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/// Create a new face
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FaceIter create_face()
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FaceIter create_face()
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{
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{
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face_db.push_back(Face());
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face_db.push_back(Face());
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return --face_db.end();
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return --face_db.end();
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}
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}
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/// Create a new halfedge.
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/// Create a new halfedge.
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HalfEdgeIter create_halfedge()
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HalfEdgeIter create_halfedge()
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{
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{
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halfedge_db.push_back(HalfEdge());
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halfedge_db.push_back(HalfEdge());
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return --halfedge_db.end();
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return --halfedge_db.end();
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}
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}
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/// Erase halfedge. Assumes it is safe to do so. Use with care.
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/// Erase halfedge. Assumes it is safe to do so. Use with care.
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void erase_halfedge(HalfEdgeIter he)
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void erase_halfedge(HalfEdgeIter he)
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{
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{
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halfedge_db.erase(he);
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halfedge_db.erase(he);
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}
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}
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/// Erase vertex. Assumes it is safe to do so. Use with care.
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/// Erase vertex. Assumes it is safe to do so. Use with care.
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void erase_vertex(VertexIter v)
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void erase_vertex(VertexIter v)
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{
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{
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vertex_db.erase(v);
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vertex_db.erase(v);
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}
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}
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/// Erase face. Assumes it is safe to do so. Use with care.
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/// Erase face. Assumes it is safe to do so. Use with care.
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void erase_face(FaceIter f)
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void erase_face(FaceIter f)
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{
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{
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face_db.erase(f);
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face_db.erase(f);
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}
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}
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/// Return iterator pointing to the first halfedge.
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/// Return iterator pointing to the first halfedge.
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HalfEdgeIter halfedges_begin() { return halfedge_db.begin();}
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HalfEdgeIter halfedges_begin() { return halfedge_db.begin();}
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/// Return iterator pointing to beyond the last halfedge.
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/// Return iterator pointing to beyond the last halfedge.
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HalfEdgeIter halfedges_end() { return halfedge_db.end(); }
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HalfEdgeIter halfedges_end() { return halfedge_db.end(); }
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/// Return iterator pointing to the first vertex.
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/// Return iterator pointing to the first vertex.
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VertexIter vertices_begin() { return vertex_db.begin();}
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VertexIter vertices_begin() { return vertex_db.begin();}
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/// Return iterator pointing to beyond the last vertex.
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/// Return iterator pointing to beyond the last vertex.
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VertexIter vertices_end() { return vertex_db.end(); }
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VertexIter vertices_end() { return vertex_db.end(); }
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/// Return iterator pointing to the first face.
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/// Return iterator pointing to the first face.
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FaceIter faces_begin() { return face_db.begin(); }
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FaceIter faces_begin() { return face_db.begin(); }
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/// Return iterator pointing to beyond the last face.
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/// Return iterator pointing to beyond the last face.
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FaceIter faces_end() { return face_db.end(); }
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FaceIter faces_end() { return face_db.end(); }
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/** \brief HalfEdge collapse precondition.
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/** \brief HalfEdge collapse precondition.
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If this function does not return true, it is illegal to collapse
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If this function does not return true, it is illegal to collapse
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the halfedge given as second arg. The reason is that the collapse
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the halfedge given as second arg. The reason is that the collapse
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would violate the manifold property of the mesh.
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would violate the manifold property of the mesh.
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The test is as follows.
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The test is as follows.
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1. For the two vertices adjacent to the edge, we generate
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1. For the two vertices adjacent to the edge, we generate
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a list of all their neighbouring vertices. We then generate a
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a list of all their neighbouring vertices. We then generate a
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list of the vertices that occur in both these lists. That is,
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list of the vertices that occur in both these lists. That is,
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we find all vertices connected by edges to both endpoints
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we find all vertices connected by edges to both endpoints
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of the edge and store these in a list.
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of the edge and store these in a list.
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2. For both faces incident on the edge, check whether they
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2. For both faces incident on the edge, check whether they
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are triangular. If this is the case, the face will be removed,
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are triangular. If this is the case, the face will be removed,
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and it is ok that the the third vertex is connected to both
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and it is ok that the the third vertex is connected to both
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endpoints. Thus the third vertex in such a face is removed
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endpoints. Thus the third vertex in such a face is removed
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from the list generated in 1.
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from the list generated in 1.
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3. If the list is now empty, all is well. Otherwise, there
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3. If the list is now empty, all is well. Otherwise, there
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would be a vertex in the new mesh with two edges connecting
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would be a vertex in the new mesh with two edges connecting
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it to the same vertex. Return false.
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it to the same vertex. Return false.
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4. TETRAHEDRON TEST:
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4. TETRAHEDRON TEST:
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If the valency of both vertices is
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If the valency of both vertices is
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three, and the incident faces are triangles, we also disallow
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three, and the incident faces are triangles, we also disallow
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the operation. Reason: It introduces a vertex of valency two
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the operation. Reason: It introduces a vertex of valency two
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and if the final two polygons incident on the vertices
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and if the final two polygons incident on the vertices
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that are adjacent to the edge being collapsed are triangles, then
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that are adjacent to the edge being collapsed are triangles, then
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the construction will collapse
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the construction will collapse
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5. VALENCY 4 TEST:
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5. VALENCY 4 TEST:
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If a face adjacent to the edge being collapsed is a triangle,
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If a face adjacent to the edge being collapsed is a triangle,
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it will disappear, and the valency of the final vertex beloning to
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it will disappear, and the valency of the final vertex beloning to
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this edge will be reduced by one. Hence this valency should be at
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this edge will be reduced by one. Hence this valency should be at
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least 4. A valency three vertex will be reduced to a valency two
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least 4. A valency three vertex will be reduced to a valency two
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vertex which is considered illegal.
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vertex which is considered illegal.
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6. PREVENT MERGING HOLES:
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6. PREVENT MERGING HOLES:
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We do not want to collapse an edge if its end points are boundary
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We do not want to collapse an edge if its end points are boundary
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vertices, but its two adjacent faces are not NULL faces, because
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vertices, but its two adjacent faces are not NULL faces, because
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in that case we create a vertex where two holes meet. A non manifold
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in that case we create a vertex where two holes meet. A non manifold
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situation. */
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situation. */
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bool collapse_precond(VertexIter, HalfEdgeIter);
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bool collapse_precond(VertexIter, HalfEdgeIter);
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/** Collapse the halfedge given as second argument.
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/** Collapse the halfedge given as second argument.
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The first argument is the vertex that is being removed. The
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second is a halfedge pointing away from that vertex.
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The first argument
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The final argument is a boolean indicating whether the vertex
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is the vertex that is being removed. The second is a halfedge pointing
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that survives the collapse should have a position which is the
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away from that vertex. This function is not guaranteed
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average of its own position and the vertex that is removed.
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By default false.
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This function is not guaranteed to keep the mesh sane unless,
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to keep the mesh sane unless, collapse_precond has returned true. */
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collapse_precond has returned true.
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189 |
*/
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void collapse_halfedge(VertexIter, HalfEdgeIter, bool=false);
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190 |
void collapse_halfedge(VertexIter, HalfEdgeIter, bool=false);
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/** Split a face.
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/** Split a face (first argument) by connecting two vertices (the
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193 |
The face given as first argument is split by connecting two
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next two arguments). */
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vertices (the next two arguments). */
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FaceIter split_face(FaceIter, VertexIter, VertexIter);
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195 |
FaceIter split_face(FaceIter, VertexIter, VertexIter);
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196 |
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/** Insert a new vertex on the halfedge given as argument. */
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197 |
/** Insert a new vertex on the halfedge given as argument.
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198 |
The new halfedge is insterted as the previous edge to the one
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199 |
given as argument.
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200 |
*/
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VertexIter Manifold::split_edge(HalfEdgeIter h);
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201 |
VertexIter Manifold::split_edge(HalfEdgeIter h);
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202 |
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/** Triangulate a polygonal face by repeatedly calling splitface. */
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203 |
/** Triangulate a polygonal face by repeatedly calling split_face.
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204 |
Triangulate iteratively splits triangles off a polygon. The first
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205 |
triangle split off is the one connecting f->last->vert and
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206 |
f->last->next->next->vert.
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207 |
*/
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void triangulate(FaceIter);
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208 |
void triangulate(FaceIter);
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209 |
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/** Triangulate a polygon by inserting a vertex at the barycenter and
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210 |
/** Triangulate a polygon by inserting a vertex at the barycenter and
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connecting all vertices to this vertex. */
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211 |
connecting all vertices to this vertex.
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212 |
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213 |
The word "safe" means that it is less likely to create flipped
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214 |
triangles than the normal triangulate. On the other hand, it
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215 |
introduces more vertices and probably makes the triangles more
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216 |
acute.
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217 |
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218 |
This function simply calls face_insert_point.
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219 |
*/
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VertexIter safe_triangulate(FaceIter f);
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220 |
VertexIter safe_triangulate(FaceIter f);
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221 |
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/** Insert a new vertex (second arg.) in a face (first arg.).
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222 |
/** Insert a new vertex (second arg.) in a face (first arg.).
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This operation splits an N-gon into N triangles. */
|
223 |
This operation splits an N-gon into N triangles.
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224 |
In the current implementation the original face is erased.
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225 |
This means that the iterator is not valid after the function
|
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226 |
returns.
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227 |
*/
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void face_insert_point(FaceIter f, VertexIter);
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228 |
void face_insert_point(FaceIter f, VertexIter);
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229 |
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/** Merges two faces into a single polygon. The first face is the first
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230 |
/** Merges two faces into a single polygon. The first face is the first
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argument. The second face is adjacent to the first along the
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231 |
argument. The second face is adjacent to the first along the
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halfedge given as second argument. */
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232 |
halfedge given as second argument. */
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bool merge_faces(FaceIter f, HalfEdgeIter h);
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233 |
bool merge_faces(FaceIter f, HalfEdgeIter h);
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234 |
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/** flips an edge. Returns false if flipping cannot be performed.
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235 |
/** Flip an edge. Returns false if flipping cannot be performed.
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This is either because one of the two adjacent faces is not
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236 |
This is either because one of the two adjacent faces is not
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a triangle, or because either end point has valency three or
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237 |
a triangle, or because either end point has valency three or
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because the vertices that will be connected already are. */
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238 |
because the vertices that will be connected already are. */
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bool flip(HalfEdgeIter);
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239 |
bool flip(HalfEdgeIter);
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240 |
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/** Performs a series of tests to check that this is a valid manifold.
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241 |
/** Performs a series of tests to check that this is a valid manifold.
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| 220 |
This function is not rigorously constructed but seems to catch
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242 |
This function is not rigorously constructed but seems to catch
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| 221 |
all problems so far. */
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243 |
all problems so far. */
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| 222 |
bool is_valid();
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244 |
bool is_valid();
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| 223 |
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245 |
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| 224 |
/** Give each vertex a unique id corresponding to its iterator
|
246 |
/** Give each vertex a unique id corresponding to its iterator
|
| 225 |
position */
|
247 |
position */
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| 226 |
void enumerate_vertices();
|
248 |
void enumerate_vertices();
|
| 227 |
|
249 |
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| 228 |
/** Give each halfedge a unique id corresponding to its iterator
|
250 |
/** Give each halfedge a unique id corresponding to its iterator
|
| 229 |
position */
|
251 |
position */
|
| 230 |
void enumerate_halfedges();
|
252 |
void enumerate_halfedges();
|
| 231 |
|
253 |
|
| 232 |
/** Give each face a unique id corresponding to its iterator
|
254 |
/** Give each face a unique id corresponding to its iterator
|
| 233 |
position */
|
255 |
position */
|
| 234 |
void enumerate_faces();
|
256 |
void enumerate_faces();
|
| 235 |
|
257 |
|
| 236 |
};
|
258 |
};
|
| 237 |
|
259 |
|
| 238 |
|
260 |
|
| 239 |
}
|
261 |
}
|
| 240 |
#endif
|
262 |
#endif
|
| 241 |
|
263 |
|