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/* ----------------------------------------------------------------------- *

 * This file is part of GEL, http://www.imm.dtu.dk/GEL

 * Copyright (C) the authors and DTU Informatics

 * For license and list of authors, see ../../doc/intro.pdf

 * ----------------------------------------------------------------------- */

#include "dual.h"

#include <vector>

#include <CGLA/Vec3f.h>

#include "Manifold.h"

#include "AttributeVector.h"

namespace HMesh

{

    using namespace std;

    using namespace CGLA;

    void dual(Manifold& m)

    {

    // make sure every face knows its number

    int i = 0;

    FaceAttributeVector<int> ftouched(m.total_faces());

    for(FaceIDIterator f = m.faces_begin(); f != m.faces_end(); ++f, ++i)

        ftouched[*f] = i;

    vector<Vec3f> vertices;

    vertices.resize(m.active_faces());

    vector<int> faces;

    vector<int> indices;

    // Create new vertices. Each face becomes a vertex whose position

    // is the centre of the face

    i = 0;

    for(FaceIDIterator f = m.faces_begin(); f != m.faces_end(); ++f, ++i)

        vertices[i] = centre(m, *f);

    // Create new faces. Each vertex is a new face with N=valency of vertex

    // edges.

    for(VertexIDIterator v = m.vertices_begin(); v!= m.vertices_end(); ++v){

        if(boundary(m, *v))

            continue;

        HalfEdgeWalker w = m.halfedgewalker(*v);

        vector<int> index_tmp;

        for(; !w.full_circle(); w = w.circulate_vertex_cw())

            index_tmp.push_back(ftouched[w.face()]);

        // Push vertex indices for this face onto indices vector.

        // The circulator moves around the face in a clockwise fashion

        // so we just reverse the ordering.

        indices.insert(indices.end(), index_tmp.rbegin(), index_tmp.rend());

        // Insert face valency in the face vector.

        faces.push_back(w.no_steps());

    }

    // Clear the manifold before new geometry is inserted.

    m.clear();

    // And build

    m.build(    vertices.size(), 

                reinterpret_cast<float*>(&vertices[0]), 

                faces.size(), 

                &faces[0],

                &indices[0]);

    }

}