CGAL users discussion list

["Kwangtaek Kim" <>]

Hello,

 

I am trying to implement subdivision with arbitrary number of points (based on barycentric coordinate) inside each triangle. For example, with u,v,w of barycentric coordinate, I can define any number of Cartesian points to add inside a triangle for subdivision. I am modifying Quad-triangle.h written by Pierre Alliez.  However, I feel difficulty to create halfedges in case of points which are not on the edge. If we look at Quad-triangle.h, it is working for half subdivision on each edge which is a simple case. But if we have some points which are not on edge but inside a triangle, how can we create halfedge to connect all added points?  I have tried to implement it as the below but it did not work.

Is there anyone who knows how to solve this problem? Thank you for your help.

 

Samuel

 

******************************************************************************

// and as many as #facets with degree > 3

    m_pMesh->tag_facets(-1);

    Polyhedron::Facet_iterator pFacet;

    for(pFacet = m_pMesh->facets_begin();

        pFacet != m_pMesh->facets_end();

        pFacet++)

    {

                unsigned int degree = Polyhedron::degree(pFacet);

                CGAL_assertion(degree >= 3);

 

                                if(degree == 3)

                                continue;

 

                                Polyhedron::Halfedge_handle pHalfedge = pFacet->halfedge();

                 

                 // Get trhee points of a triangle

                                const Point& p1 = pHalfedge->vertex()->point();

                                const Point& p2 = pHalfedge->opposite()->vertex()->point();

                                const Point& p3 = pHalfedge->next()->vertex()->point(); // to get the third vertex of a traingle

                 

                 // store three points of a triangle into variables

                                 float x0 = p1.x() ; float y0 = p1.y(); float z0 = p1.z();

                                 float x1 = p2.x() ; float y1 = p2.y(); float z1 = p2.z();

                                 float x2 = p3.x() ; float y2 = p3.y(); float z2 = p3.z();

                                 for(int i=0;i<npnts;i++ )   // add npnts points inside a triangle for sudbidivion

                                 {

                                                   float x=0.0;float y=0.0;float z=0.0; // variable to store a cartesian point from barycentric coordinate

                                                   float u= r[i][0]; float v= r[i][1]; float w= r[i][2]; // Prestored barycentric coordinate

                 

                                                   // generate a cartesian point with the corresponding baricentric coordinate (u,v,w)

                                                   barycentric.ConvertCartesian(x0,y0,z0,x1,y1,z1,x2,y2,z2,u,v,w,&x,&y,&z);

                                                  

                                                   Point point = Point(x,y,z); // store a cartesian point

                                                   B.add_vertex(point); // add to the builder

                                                   pFacet->tag(index); // tag index ? I am not sure if this is right

                                   index++;

                                  }  

                 }