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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]);
    }
}