C++ Facet_iterator::center方法代码示例

void renewAttrs( Polyhedron & poly )
{
    // assign IDs to vertices
    for ( Vertex_iterator vi = poly.vertices_begin(); vi != poly.vertices_end(); ++vi ) {
	vi->nCuts()	= 0;
    }

    // assign IDs to faces: the dual vertex and the dual coordinates-the center coordinates
    for ( Facet_iterator fi = poly.facets_begin(); fi != poly.facets_end(); ++fi ) {
	fi->piece()	= NO_INDEX;
	Vector3 sum( 0.0, 0.0, 0.0 );
	Halfedge_facet_circulator hfc = fi->facet_begin();
	do {
	    sum = sum + ( hfc->vertex()->point() - CGAL::ORIGIN );
	} while ( ++hfc != fi->facet_begin() );
	sum = sum / ( double )CGAL::circulator_size( hfc );
	fi->center() = CGAL::ORIGIN + sum;
    }

    // assign the same IDs to the identical/ opposite halfedges
    for ( Halfedge_iterator hi = poly.halfedges_begin(); hi != poly.halfedges_end(); ++hi ) {
	hi->label()		= DEFAULT_LABEL;
	hi->match()		= DEFAULT_LABEL;
	hi->cycle()		= NO_INDEX;
	hi->connect()		= true;
	hi->visit()		= false;
	hi->path()		= NO_INDEX;
	hi->orient()		= true;
	// We individually handle hi->fixed
    }
}

//------------------------------------------------------------------------------
//	Initialize the dual center 
//------------------------------------------------------------------------------
void initAttrs( Polyhedron & poly )
{
    // assign IDs to vertices
    int vID = 0;
    for ( Vertex_iterator vi = poly.vertices_begin(); vi != poly.vertices_end(); ++vi ) {
	vi->id()	= vID++;
	vi->label()	= DEFAULT_LABEL;
	vi->nCuts()	= 0;
    }
    cerr << "Total number of vertices = " << vID << endl;

    // assign IDs to faces: the dual vertex and the dual coordinates-the center coordinates
    int fID = 0;
    for ( Facet_iterator fi = poly.facets_begin(); fi != poly.facets_end(); ++fi ) {
	fi->id()	= fID++;
	// fi->label()	= DEFAULT_LABEL;
	fi->piece()	= NO_INDEX;
	Vector3 sum( 0.0, 0.0, 0.0 );
	Halfedge_facet_circulator hfc = fi->facet_begin();
	do {
	    sum = sum + ( hfc->vertex()->point() - CGAL::ORIGIN );
	} while ( ++hfc != fi->facet_begin() );
	sum = sum / ( double )CGAL::circulator_size( hfc );
	fi->center() = CGAL::ORIGIN + sum;
	// cerr << " Barycenter No. " << fid-1 << " : " << bary[ fid-1 ] << endl;
    }
    cerr << "Total number of facets = " << fID << endl;

    // initialize the halfedge IDs
    for ( Halfedge_iterator hi = poly.halfedges_begin(); hi != poly.halfedges_end(); ++hi ) {
	hi->id() = NO_INDEX;
    }

    // assign the same IDs to the identical/ opposite halfedges
    int eID = 0;
    for ( Halfedge_iterator hi = poly.halfedges_begin(); hi != poly.halfedges_end(); ++hi ) {
	if ( hi->id() == NO_INDEX ) {
	    assert( hi->opposite()->id() == NO_INDEX );
	    hi->id() = eID;
	    hi->opposite()->id() = eID;
	    eID++;
	    hi->label()		= hi->opposite()->label()	= DEFAULT_LABEL;
	    hi->match()		= hi->opposite()->match()	= DEFAULT_LABEL;
	    hi->cycle()		= hi->opposite()->cycle()	= NO_INDEX;
	    hi->weight()	= hi->opposite()->weight()	= 0.0;
	    hi->connect()	= hi->opposite()->connect()	= true;
	    hi->visit()		= hi->opposite()->visit()	= false;
	    // We individually handle hi->fixed
	}
    }
    cerr << "Total number of edges = " << eID << endl;
}

//------------------------------------------------------------------------------
//	Compute and store the results of dual graphs into appropriate variables
//
//  computeDual( mesh, whole, bary, mid ); 
//------------------------------------------------------------------------------
void computeDual( Polyhedron & poly, Graph & dual,
		  vector< Point3 > & bary, vector< Point3 > & mid )
{
    // initialize the array of face barycenters: refer to the point at which the gravitational forces exerted by 2 objects are equal

    bary.clear();
    bary.resize( poly.size_of_facets() );

    // initialize the dual graph with dual vertices
    dual.clear();
    int fid = 0;
    for ( Facet_iterator fi = poly.facets_begin(); fi != poly.facets_end(); ++fi ) {
	// add a vertex: each face equals to each dual vertex
	add_vertex( dual );
	bary[ fid++ ] = fi->center(); 
	// cerr << " Barycenter No. " << fid-1 << " : " << bary[ fid-1 ] << endl;
    }

    int size_of_edges = poly.size_of_halfedges() / 2; //redundant

    // initialize the array of midpoints
    mid.clear();
    mid.resize( size_of_edges );

    // initialize the array of lengths
    // length.clear();
    // length.resize( size_of_edges );

    // construct the connecitivity of the dual graph
    for ( Halfedge_iterator hi = poly.halfedges_begin(); hi != poly.halfedges_end(); ++hi ) {
	int origID = hi->facet()->id(); // the face
	int destID = hi->opposite()->facet()->id(); // the neighbor face
	Point3 origCoord = hi->vertex()->point();
	Point3 destCoord = hi->opposite()->vertex()->point();
	Vector3 dispVec = origCoord - destCoord;
	Point3 midCoord = destCoord + 0.5 * dispVec;
	// double curLength = sqrt( dispVec.squared_length() ); // the length between two connected vertices
#ifdef DEBUG
	cerr << origID << " -- " << destID << endl;
#endif	// DEBUG	
	
	if ( origID < destID )
		add_edge( origID, destID, hi->id(), dual );  
		
	mid[ hi->id() ] = midCoord;
	hi->mid() = hi->opposite()->mid() = midCoord;
	hi->weight() = hi->opposite()->weight() = 1.0;
    }
}