表面網格 - 刪除邊緣，循環進入無限循環CGAL

Question

我正在製作切片功能，刪除長度爲y的部分網格。當我嘗試刪除網格的已刪除的面部邊緣時，問題就開始了，它會進入無限循環。

問題出現在哪裏！

//removes edge - puts in infinite loop 
BOOST_FOREACH(halfEdge_descriptor hed, halfedges_around_face(mesh.halfedge(fd), mesh)){ 
edge_descriptor ed = mesh.edge(hed); 
mesh.remove_edge(ed); 
} 

當我通過，halfedges迭代，它遍歷它應該，但是當我嘗試以除去半邊，通過轉換爲

remove_edge（Edge_index ED）

它進入無限循環。

任何人都可以解釋它爲什麼這樣做，我該如何解決它？

Full Code！

void Mesh::slice(SurfaceMesh &mesh, double lengthToCut){ 
    typedef SurfaceMesh::Vertex_index vertex_descriptor; 
    typedef SurfaceMesh::Face_index face_descriptor; 
    typedef SurfaceMesh::Halfedge_index halfEdge_descriptor; 
    typedef SurfaceMesh::Edge_index edge_descriptor; 
    double y = findMaxY(mesh) - lengthToCut; // length of a mesh 
    //;oops over faces 
    BOOST_FOREACH(face_descriptor fd, mesh.faces()){ 
    int verticesLargerThan = 0; 
    //loops over vertices of face 
    BOOST_FOREACH(vertex_descriptor vd,vertices_around_face(mesh.halfedge(fd), mesh)){ 
     if(CGAL::compare (mesh.point(vd)[1], y) == CGAL::LARGER){ 
     verticesLargerThan++; 
     // if all vertices y coordinates are larger than double y, then removes face 
     if(verticesLargerThan == 3){ 
      mesh.remove_face(fd); 
      //mesh.remove_face(fd); 
      int removedFaceCounter = 0; 
      BOOST_FOREACH(face_descriptor rfd,faces_around_face(mesh.halfedge(fd), mesh)){ 
      if(mesh.is_removed(rfd)){ 
       removedFaceCounter++; 
      } 
      //remove all edges and vertices of face if face is not linked to any other face 
      if(removedFaceCounter == 3){ 
       //removes edge - puts in infinite loop 
       BOOST_FOREACH(halfEdge_descriptor hed, halfedges_around_face(mesh.halfedge(fd), mesh)){ 
       edge_descriptor ed = mesh.edge(hed); 
       mesh.remove_edge(ed); 
       } 
       //removes vertice 
       BOOST_FOREACH(vertex_descriptor rvd,vertices_around_face(mesh.halfedge(fd), mesh)){ 
       //removes vertice if its not linked to any face 
       bool allFacesRemoved = true; 
       BOOST_FOREACH(face_descriptor rfvd, faces_around_target(mesh.halfedge(fd), mesh)){ 

        if(!mesh.is_removed(rfvd)){ 
        allFacesRemoved = false; 
        break; 
        } 
       } 
       if(allFacesRemoved){ 
        mesh.remove_vertex(rvd); 
       } 
       } 
      } 
      } 
     } 
     } 
    } 
    } 

Answer 1

這是一個經典的錯誤：刪除正在迭代的元素。在這種特殊情況下，您將在邊緣迭代邊緣的同時去除邊緣。你不太可能會發現初始邊緣停止迭代，因此無限循環。