vcglib/vcg/complex/algorithms/polygon_support.h

/****************************************************************************
* VCGLib                                                            o o     *
* Visual and Computer Graphics Library                            o     o   *
*                                                                _   O  _   *
* Copyright(C) 2004                                                \/)\/    *
* Visual Computing Lab                                            /\/|      *
* ISTI - Italian National Research Council                           |      *
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* This program is distributed in the hope that it will be useful,           *
* but WITHOUT ANY WARRANTY; without even the implied warranty of            *
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the             *
* GNU General Public License (http://www.gnu.org/licenses/gpl.txt)          *
* for more details.                                                         *
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****************************************************************************/

#ifndef __VCGLIB_POLYGON_SUPPORT
#define __VCGLIB_POLYGON_SUPPORT

#include <vector>
#include <vcg/complex/algorithms/subset.h>
#include <vcg/simplex/face/jumping_pos.h>
#include <vcg/space/planar_polygon_tessellation.h>

namespace vcg {
namespace tri {
	/// \ingroup trimesh

	/// \headerfile polygon_support.h vcg/complex/algorithms/polygon_support.h

	/// \brief This class is used convert between polygonal meshes and triangular meshes

	/**
	This class contains two members that allow to build a triangular mesh from a polygonal mesh
	and viceversa. In a trimesh, the generic polygons with n sides are codified represented by tagging the internal edge of the face
	with the SetF.
	*/

	template <class TriMeshType,class PolyMeshType >
	struct PolygonSupport{

	/**
	Given a tri mesh (with per-face normals and FF connectivity),
	merges flat faces into larger polygons.
	**/
	static void MergeFlatFaces(TriMeshType & tm, double tolerance = 0.1E-4){
		typedef typename TriMeshType::CoordType::ScalarType Scalar;
		typedef typename TriMeshType::FaceIterator FaceIterator;
		typedef typename TriMeshType::FaceType FaceType;
		Scalar minDist = 1 - Scalar(tolerance);
		for (FaceIterator fi=tm.face.begin(); fi!=tm.face.end(); fi++) {
			FaceType *fa = &*fi;
			for (int w=0; w<3; w++) {
				FaceType *fb = fa->FFp(w);
				if ( (fb>fa) && (fa->N()*fb->N() > minDist) ) {
					fa->SetF( w );
					fb->SetF( fa->FFi(w) ); // reciprocate
				}
			}
		}
	}

	/**
	Import a  trianglemesh from a polygon mesh
	**/
	static void ImportFromPolyMesh(TriMeshType & tm,  PolyMeshType & pm){
		std::vector<typename PolyMeshType::CoordType> points;
		std::vector<int> faces;

		// the vertices are the same, simply import them
		typename PolyMeshType::VertexIterator vi;
		typename TriMeshType::FaceIterator tfi,tfib ;
		typename TriMeshType ::VertexIterator tvi = Allocator<TriMeshType>::AddVertices(tm,pm.vert.size());
		int cnt = 0;
		for(tvi = tm.vert.begin(),vi = pm.vert.begin(); tvi != tm.vert.end(); ++tvi,++vi,++cnt)
			if(!(*vi).IsD()) (*tvi).ImportData(*vi); else vcg::tri::Allocator<TriMeshType>::DeleteVertex(tm,(*tvi));

		typename PolyMeshType::FaceIterator fi;
		for(fi = pm.face.begin(); fi != pm.face.end(); ++fi)
		if(!((*fi).IsD())){
		points.clear();
			for(int i  = 0; i < (*fi).VN(); ++i) {
				typename	PolyMeshType::VertexType * v = (*fi).V(i);
				points.push_back(v->P());
			}
			faces.clear();
			TessellatePlanarPolygon3(points,faces);
			tfib = tfi  = Allocator<TriMeshType>::AddFaces(tm,faces.size()/3);
			for(size_t i = 0; tfi !=  tm.face.end();++tfi){
				(*tfi).V(0) = &tm.vert[ (*fi).V( faces[i]  ) - &(*pm.vert.begin())];
				(*tfi).V(1) = &tm.vert[ (*fi).V( faces[i+1]) - &(*pm.vert.begin())];
				(*tfi).V(2) = &tm.vert[ (*fi).V( faces[i+2]) - &(*pm.vert.begin())];
				// set the F flags
				if( (faces[i  ]+1)%points.size() != size_t(faces[i+1])) (*tfi).SetF(0);
				if( (faces[i+1]+1)%points.size() != size_t(faces[i+2])) (*tfi).SetF(1);
				if( (faces[i+2]+1)%points.size() != size_t(faces[i  ])) (*tfi).SetF(2);
				i+=3;
			}

		}
	}


	/**
	Import a polygon mesh from a triangle mesh
	**/
	static void ImportFromTriMesh( PolyMeshType & pm,  TriMeshType & tm){

		// the vertices are the same, simply import them
		int cnt = 0;
		typename TriMeshType ::ConstVertexIterator tvi;
		typename PolyMeshType::VertexIterator vi  = vcg::tri::Allocator<PolyMeshType>::AddVertices(pm,tm.vert.size());
		for(tvi = tm.vert.begin(); tvi != tm.vert.end(); ++tvi,++vi,++cnt) 
			if(!(*tvi).IsD())(*vi).ImportData(*tvi); else vcg::tri::Allocator<PolyMeshType> ::DeleteVertex(pm,(*vi));

		// convert the faces
		typename TriMeshType::FaceIterator tfi;
		vcg::face::JumpingPos<typename TriMeshType::FaceType> p;

		for( tfi = tm.face.begin(); tfi != tm.face.end(); ++tfi) if(!(*tfi).IsD() && !(*tfi).IsV())
		{
			std::vector<typename TriMeshType::VertexPointer> vs;// vertices of the polygon
			std::vector<typename TriMeshType::FacePointer> fs;// triangle faces corresponding to the polygon


			// find a non tagged edge
			int se = 0;
			for(;se < 3;++se) if (!(*tfi).IsF(se)) break;

			// initialize a pos on the first non tagged edge
			typename TriMeshType::VertexPointer v0 = (*tfi).V(se);
			p.F() = &(*tfi);
			p.E() = se;
			p.V() = p.F()->V(p.F()->Next(se));
			p.FlipE();

			vs.push_back(p.F()->V(se));
	
			do{
				while(p.F()->IsF(p.E())) { fs.push_back(p.F()); p.FlipF(); p.FlipE(); p.F()->SetV();} 
				vs.push_back(p.F()->V(p.E()));
				p.FlipV();
				p.FlipE();
			} while( p.V() != v0 );

			//now vs  contains all the vertices of the polygon (still in the trimesh)
			typename PolyMeshType::FaceIterator pfi =  vcg::tri::Allocator<PolyMeshType>::AddFaces(pm,1);
			(*pfi).Alloc(vs.size());
			for(size_t i  = 0 ; i < vs.size(); ++i)
				(*pfi).V(i) = ( typename PolyMeshType::VertexType*)  & pm.vert[vs[i]-&(*tm.vert.begin())];
			// here handle the other compoenents of the face (how the conponents of the n triangle faces goes in the 
			// the property of the polygon (e.g. the normal, the color, the quality and so on)
			// TODO

		}
	}

	// Given a facepointer, it build a vector with all the vertex pointer
	// around the polygonal face determined by the current FAUX-EDGE markings
	// It assumes that the mesh is 2Manifold and has FF adjacency already computed
	// NOTE: All the faces touched are marked as visited. (so for example you can avoid to get twice the same polygon)
	static void ExtractPolygon(typename TriMeshType::FacePointer tfp, std::vector<typename TriMeshType::VertexPointer> &vs)
	{
		vs.clear();
		// find a non tagged edge
		int se = -1;
		for(int i=0; i<3; i++) if (!( tfp->IsF(i))) { se = i; break;}

		// all faux edges return an empty vertex vector!
		if(se==-1) return;

		// initialize a pos on the first non faux edge
		typename TriMeshType::VertexPointer v0 = tfp->V(se);

		vcg::face::Pos<typename TriMeshType::FaceType> p(tfp,se,v0);
		vcg::face::Pos<typename TriMeshType::FaceType> start(p);

		do
		{
			assert(!p.F()->IsF(p.E()));
			vs.push_back(p.F()->V(p.E()));
			p.FlipE();

			while( p.F()->IsF(p.E()) )
			{
				p.F()->SetV();
				p.FlipF();
				p.FlipE();
			}
			p.FlipV();
		} while(p!=start);
	}

}; // end of struct
}} // end namespace vcg::tri

#endif // __VCGLIB_TRI_CLIP