mirror of https://github.com/CGAL/cgal
updated doc
This commit is contained in:
Pierre Alliez
parent
ca59c2551e
commit
a503ce1904
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@ -14,12 +14,12 @@ all:
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make ps
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make pdf
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make clean
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\rm *.ps
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\rm *.ps *.tmp
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clear
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ls -l
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clean:
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\rm *.aux *.dvi *.log
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\rm *.aux *.dvi *.log *.out *.blg *.bbl
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superclean:
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\rm *.ps *.pdf *~
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Binary file not shown.
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@ -931,6 +931,398 @@ Polyhedron (see Section~\ref{sec:builder}).
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Subdivision engine
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{ \scriptsize
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\begin{verbatim}
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#include "enriched_polyhedron.h"
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#include "builder.h"
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template <class HDS,class Polyhedron,class kernel>
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class CModifierQuadTriangle : public CGAL::Modifier_base<HDS>
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{
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private:
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typedef typename kernel::FT FT;
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typedef typename HDS::Vertex Vertex;
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typedef typename Vertex::Point Point;
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typedef typename HDS::Face_handle Face_handle;
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typedef typename HDS::Halfedge_handle Halfedge_handle;
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typedef typename CGAL::Enriched_polyhedron_incremental_builder_3<HDS> builder;
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typedef typename Polyhedron::Halfedge_around_vertex_circulator Halfedge_around_vertex_circulator;
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typedef typename Polyhedron::Facet_handle Facet_handle;
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typedef typename Polyhedron::Vertex_handle Vertex_handle;
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Polyhedron *m_pMesh;
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public:
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// life cycle
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CModifierQuadTriangle(Polyhedron *pMesh)
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{
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CGAL_assertion(pMesh != NULL);
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m_pMesh = pMesh;
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}
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~CModifierQuadTriangle() {}
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// subdivision
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void operator()( HDS& hds)
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{
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builder B(hds,true);
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B.begin_surface(3,1,6);
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add_vertices(B);
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add_facets(B);
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B.end_surface();
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}
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private:
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//***************************************************
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// add vertices
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//***************************************************
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void add_vertices(builder &B)
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{
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// put original vertices
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int index = 0;
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typename Polyhedron::Vertex_iterator pVertex;
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for(pVertex = m_pMesh->vertices_begin();
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pVertex != m_pMesh->vertices_end();
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pVertex++)
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{
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pVertex->tag(index);
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B.add_vertex(pVertex->point());
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index++;
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}
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// as many as #edges
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m_pMesh->tag_halfedges(-1);
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typename Polyhedron::Halfedge_iterator pHalfedge;
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for(pHalfedge = m_pMesh->halfedges_begin();
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pHalfedge != m_pMesh->halfedges_end();
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pHalfedge++)
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{
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if(pHalfedge->tag() != -1)
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continue;
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// simple edge bissection
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const Point& p1 = pHalfedge->vertex()->point();
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const Point& p2 = pHalfedge->opposite()->vertex()->point();
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Point point = Point(0.5f*(p1.x()+p2.x()),
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0.5f*(p1.y()+p2.y()),
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0.5f*(p1.z()+p2.z()));
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B.add_vertex(point);
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// put vertex indices on both halfedges
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pHalfedge->tag(index);
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pHalfedge->opposite()->tag(index);
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index++;
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}
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// and as many as #facets with degree > 3
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m_pMesh->tag_facets(-1);
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typename Polyhedron::Facet_iterator pFacet;
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for(pFacet = m_pMesh->facets_begin();
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pFacet != m_pMesh->facets_end();
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pFacet++)
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{
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unsigned int degree = Polyhedron::degree(pFacet);
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CGAL_assertion(degree >= 3);
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// forget about triangles, they are
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// simply 1-to-4 subdivided by edge bisection
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if(degree == 3)
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continue;
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// barycentric subdivision
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Point barycenter;
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m_pMesh->compute_facet_center(pFacet,barycenter);
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B.add_vertex(barycenter);
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pFacet->tag(index);
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index++;
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}
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}
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//***************************************************
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// add facets
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//***************************************************
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void add_facets(builder &B)
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{
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typename Polyhedron::Facet_iterator pFacet;
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for(pFacet = m_pMesh->facets_begin();
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pFacet != m_pMesh->facets_end();
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pFacet++)
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{
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unsigned int degree = Polyhedron::degree(pFacet);
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CGAL_assertion(degree >= 3);
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if(degree == 3)
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{
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typename Polyhedron::Halfedge_handle pHalfedge = pFacet->halfedge();
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int i0 = pHalfedge->tag();
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int i1 = pHalfedge->vertex()->tag();
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int i2 = pHalfedge->next()->tag();
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int i3 = pHalfedge->next()->vertex()->tag();
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int i4 = pHalfedge->next()->next()->tag();
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int i5 = pHalfedge->next()->next()->vertex()->tag();
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CGAL_assertion(i0 >= 0);
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CGAL_assertion(i1 >= 0);
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CGAL_assertion(i2 >= 0);
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CGAL_assertion(i3 >= 0);
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CGAL_assertion(i4 >= 0);
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CGAL_assertion(i5 >= 0);
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// create 4 triangles
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B.begin_facet();
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B.add_vertex_to_facet(i1);
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B.add_vertex_to_facet(i2);
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B.add_vertex_to_facet(i0);
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const Halfedge_handle& h1 = B.end_facet();
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B.begin_facet();
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B.add_vertex_to_facet(i3);
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B.add_vertex_to_facet(i4);
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B.add_vertex_to_facet(i2);
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const Halfedge_handle& h2 = B.end_facet();
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B.begin_facet();
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B.add_vertex_to_facet(i5);
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B.add_vertex_to_facet(i0);
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B.add_vertex_to_facet(i4);
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const Halfedge_handle& h3 = B.end_facet();
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// center face
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B.begin_facet();
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B.add_vertex_to_facet(i0);
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B.add_vertex_to_facet(i2);
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B.add_vertex_to_facet(i4);
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Halfedge_handle h4 = B.end_facet();
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h1->control_edge(false);
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h1->next()->control_edge(false);
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h1->next()->next()->control_edge(false);
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h2->control_edge(false);
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h2->next()->control_edge(false);
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h2->next()->next()->control_edge(false);
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h3->control_edge(false);
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h3->next()->control_edge(false);
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h3->next()->next()->control_edge(false);
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h4->control_edge(false);
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h4->next()->control_edge(false);
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h4->next()->next()->control_edge(false);
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if(pHalfedge->control_edge())
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{
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h1->control_edge(true);
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h3->next()->control_edge(true);
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}
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if(pHalfedge->next()->control_edge())
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{
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h1->next()->control_edge(true);
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h2->control_edge(true);
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}
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if(pHalfedge->next()->next()->control_edge())
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{
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h2->next()->control_edge(true);
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h3->control_edge(true);
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}
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}
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else
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{
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// i1: index of barycenter vertex
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int i1 = pFacet->tag();
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CGAL_assertion(i1 >= 0);
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// for each halfedge
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typename Polyhedron::Halfedge_around_facet_circulator h;
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h = pFacet->facet_begin();
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do
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{
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// i2,3,4: indices of three consecutive
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// vertices on halfedges
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int i2 = h->tag();
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int i3 = h->vertex()->tag();
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int i4 = h->next()->tag();
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CGAL_assertion(i2 >= 0);
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CGAL_assertion(i3 >= 0);
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CGAL_assertion(i4 >= 0);
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// create a quad
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B.begin_facet();
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B.add_vertex_to_facet(i3);
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B.add_vertex_to_facet(i4);
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B.add_vertex_to_facet(i1);
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B.add_vertex_to_facet(i2);
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const Halfedge_handle& pNewHalfedge = B.end_facet();
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pNewHalfedge->control_edge(false);
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pNewHalfedge->next()->control_edge(false);
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pNewHalfedge->next()->next()->control_edge(false);
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pNewHalfedge->next()->next()->next()->control_edge(false);
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if(h->control_edge())
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pNewHalfedge->control_edge(true);
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if(h->next()->control_edge())
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pNewHalfedge->next()->control_edge(true);
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}
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while(++h != pFacet->facet_begin());
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}
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}
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}
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//***************************************************
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// correcting factor
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//***************************************************
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static float correcting_factor(unsigned int ne,
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unsigned int nq)
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{
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if(ne == 2 && nq == 1)
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return -0.20505f;
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if(ne == 3 && nq == 1)
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return 0.80597f;
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if(ne == 3 && nq == 2)
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return 0.61539f;
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if(ne == 4 && nq == 1)
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return 0.34792f;
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if(ne == 4 && nq == 2)
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return 0.21380f;
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if(ne == 4 && nq == 3)
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return 0.10550f;
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return 0.0f;
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}
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public:
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//***************************************************
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// smooth vertex positions
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//***************************************************
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static void smooth(Polyhedron *pMesh,
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bool smooth_boundary = true)
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{
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CGAL_assertion(pMesh != NULL);
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// alloc position vectors
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unsigned int nb_vertices = pMesh->size_of_vertices();
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FT *pPos = new FT[3*nb_vertices];
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CGAL_assertion(pPos != NULL);
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// compute new positions
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unsigned int index = 0;
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typename Polyhedron::Vertex_iterator pVertex;
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for(pVertex = pMesh->vertices_begin();
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pVertex != pMesh->vertices_end();
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pVertex++)
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{
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// border vertices will not move
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if(Polyhedron::is_border(pVertex))
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{
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// do not smooth it
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const Point& curr = pVertex->point();
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if(!smooth_boundary)
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{
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pPos[3*index] = curr.x();
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pPos[3*index+1] = curr.y();
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pPos[3*index+2] = curr.z();
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}
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// smooth using [1/4 1/2 1/4] cubic B-spline averaging mask
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else
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{
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const typename Polyhedron::Halfedge_handle& pHalfedge =
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pMesh->get_border_halfedge(pVertex);
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CGAL_assertion(pHalfedge != NULL);
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const Point& next = pHalfedge->vertex()->point();
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const Point& prev = pHalfedge->prev()->prev()->vertex()->point();
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pPos[3*index] = 0.25f*prev.x() + 0.5f*curr.x() + 0.25f*next.x();
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pPos[3*index+1] = 0.25f*prev.y() + 0.5f*curr.y() + 0.25f*next.y();
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pPos[3*index+2] = 0.25f*prev.z() + 0.5f*curr.z() + 0.25f*next.z();
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}
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} // end is border
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else
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{
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unsigned int nb_quads = 0;
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unsigned int nb_edges = 0;
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// rotate around vertex to count #edges and #quads
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Halfedge_around_vertex_circulator
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pHalfEdge = pVertex->vertex_begin();
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Halfedge_around_vertex_circulator end = pHalfEdge;
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CGAL_For_all(pHalfEdge,end)
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{
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const Facet_handle& pFacet = pHalfEdge->facet();
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CGAL_assertion(pFacet != NULL);
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unsigned int degree = Polyhedron::degree(pFacet);
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CGAL_assertion(degree == 4 || degree == 3);
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if(degree == 4)
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nb_quads++;
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nb_edges++;
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}
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// compute coefficients
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FT ne = (FT)nb_edges;
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FT nq = (FT)nb_quads;
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FT alpha = 1.0f / (1.0f + ne/2.0f + nq/4.0f);
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FT beta = alpha / 2.0f; // edges
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FT gamma = alpha / 4.0f; // corners of incident quads
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FT eta = correcting_factor(nb_edges,nb_quads);
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// new position
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pPos[3*index] = alpha * pVertex->point().x();
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pPos[3*index+1] = alpha * pVertex->point().y();
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pPos[3*index+2] = alpha * pVertex->point().z();
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// rotate around vertex to compute new position
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pHalfEdge = pVertex->vertex_begin();
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end = pHalfEdge;
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CGAL_For_all(pHalfEdge,end)
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{
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const Facet_handle& pFacet = pHalfEdge->facet();
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CGAL_assertion(pFacet != NULL);
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unsigned int degree = Polyhedron::degree(pFacet);
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CGAL_assertion(degree == 4 || degree == 3);
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// add edge-vertex contribution
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const Point& point = pHalfEdge->prev()->vertex()->point();
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pPos[3*index] += beta * point.x();
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pPos[3*index+1] += beta * point.y();
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pPos[3*index+2] += beta * point.z();
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// add corner vertex contribution
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if(degree == 4)
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{
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const Point& corner = pHalfEdge->next()->next()->vertex()->point();
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pPos[3*index] += gamma * corner.x();
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pPos[3*index+1] += gamma * corner.y();
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pPos[3*index+2] += gamma * corner.z();
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}
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}
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// apply correction
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pPos[3*index] = pPos[3*index] +
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eta*(pPos[3*index]-pVertex->point().x());
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pPos[3*index+1] = pPos[3*index+1] +
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eta*(pPos[3*index+1]-pVertex->point().y());
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pPos[3*index+2] = pPos[3*index+2] +
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eta*(pPos[3*index+2]-pVertex->point().z());
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} // end !is border
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index++;
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}
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// set new positions
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index = 0;
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for(pVertex = pMesh->vertices_begin();
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pVertex != pMesh->vertices_end();
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pVertex++)
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{
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Point& point = pVertex->point();
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point = Point(pPos[3*index],
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pPos[3*index+1],
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pPos[3*index+2]);
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index++;
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}
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// cleanup
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delete [] pPos;
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}
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};
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\end{verbatim}}
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{ \scriptsize
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\begin{verbatim}
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template <class Polyhedron,class kernel>
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@ -961,42 +1353,6 @@ public:
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};
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\end{verbatim}}
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Subdivision using a modified incremental builder
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{ \scriptsize
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\begin{verbatim}
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template <class HDS,class Polyhedron,class kernel>
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class CModifierQuadTriangle : public CGAL::Modifier_base<HDS>
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{
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private:
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Polyhedron *m_pMesh;
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typedef typename CGAL::Enriched_builder<HDS> builder;
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public:
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// life cycle
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CModifierQuadTriangle(Polyhedron *pMesh)
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{
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m_pMesh = pMesh;
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}
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~CModifierQuadTriangle() {}
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// subdivision
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void operator()( HDS& hds)
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{
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builder B(hds,true);
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B.begin_surface(3,1,6);
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add_vertices(B);
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add_facets(B);
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B.end_surface();
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}
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...
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};
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\end{verbatim}}
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% SurfLab
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\subsection{Subdivision using a rule template}
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