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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 "flatten.h"

#include <string>

#include <fstream>

#include <vector>

#include <CGLA/Vec3d.h>

#include "Manifold.h"

#include "AttributeVector.h"

namespace HMesh

{

    using namespace std;

    using namespace CGLA;

    void flatten(Manifold& m, WeightScheme ws)

    {

        HalfEdgeAttributeVector<double> edge_weights(m.total_halfedges(), 0);

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

		{

			for(HalfEdgeWalker wv = m.halfedgewalker(*f); !wv.full_circle(); wv = wv.circulate_face_ccw())

			{

				HalfEdgeID h = wv.halfedge();

				Vec3d p1(m.pos(wv.vertex()));

				Vec3d p2(m.pos(wv.next().vertex()));

				Vec3d p0(m.pos(wv.opp().vertex()));

				if(ws == FLOATER_W){

					double ang = acos(min(1.0, max(-1.0, dot(normalize(p1-p0), normalize(p2-p0)))));

					double ang_opp = acos(min(1.0, max(-1.0, dot(normalize(p2-p1), normalize(p0-p1)))));

					double l = (p1-p0).length();

					edge_weights[h]  += tan(ang/2) / l;

					edge_weights[wv.opp().halfedge()]  += tan(ang_opp/2) / l;

				}

				else if(ws == HARMONIC_W || ws == LSCM_W){

					double a = acos(min(1.0, max(-1.0, dot(normalize(p0-p2), normalize(p1-p2)))));

					double w = max(0.0000001,0.5/tan(a));

					edge_weights[h]  += w;

					edge_weights[wv.opp().halfedge()]  += w;

				}

				else{

					edge_weights[h]  = valency(m, wv.opp().vertex());

					edge_weights[wv.opp().halfedge()]  = valency(m, wv.vertex());

				}

			}

		}

        ofstream ofs("parametrized.obj");

        ofs << "mtllib parametrized.mtl\nusemtl mat\n" << endl;

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

            ofs << "v " << m.pos(*v)[0] << " " << m.pos(*v)[1] << " " << m.pos(*v)[2] << endl;

        ofs << endl;

		VertexAttributeVector<double> touched(m.total_vertices(), 0);

        VertexIDIterator v = m.vertices_begin();

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

            if(boundary(m, *v))

                break;

        }

        int n = 0;

        HalfEdgeWalker bv = m.halfedgewalker(*v);

        do{

            ++n;

            bv = bv.next();

        }

        while(bv.vertex() != *v);

        int i = 0;

        do{

			if(i==int(n*0.25) || i==int(n*0.75))

				touched[bv.vertex()]=1;

            double a = 2.0*M_PI*double(i)/n;

            m.pos(bv.vertex()) = Vec3f(cos(a), sin(a), 0);

            ++i;

            bv = bv.next();

        }

        while(bv.vertex() != *v);

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

            if(!boundary(m, *v))

                m.pos(*v) = Vec3f(0.0);

        VertexAttributeVector<Vec3f> new_pos(m.active_vertices());

        for(int i = 0; i < 10000; ++i){

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

				if(boundary(m, *v))

				{

					if(ws == LSCM_W && touched[*v] != 1)

					{

						Vec3d p_new(0);

						double w_sum = 0;

						Vec3d grad_sum(0.0);

						HalfEdgeWalker wv = m.halfedgewalker(*v);

						for(;!wv.full_circle(); wv = wv.circulate_vertex_ccw())

                        {

							if(wv.face() != InvalidFaceID)

							{

								Vec3d p1(m.pos(wv.next().vertex()));

								Vec3d p0(m.pos(wv.vertex()));

								Vec3d area_grad = 0.5*(p1 - p0); 

								grad_sum[0] += -area_grad[1];

								grad_sum[1] += area_grad[0];

							}

                            double w = edge_weights[wv.halfedge()];

                            p_new += Vec3d(m.pos(wv.vertex()) * w);

                            w_sum += w;                            

                        }

						new_pos[*v] = (Vec3f(p_new) - Vec3f(grad_sum))/w_sum;	

					}

                    else

                        new_pos[*v] = m.pos(*v);

				}

				else

				{

					Vec3d p_new(0);

					double w_sum = 0;

					for(HalfEdgeWalker wv = m.halfedgewalker(*v); !wv.full_circle(); wv = wv.circulate_vertex_ccw()) 

					{

						double w = edge_weights[wv.halfedge()];

						p_new += Vec3d(m.pos(wv.vertex()) * w);

						w_sum += w;

					}

                    new_pos[*v] = Vec3f(p_new/w_sum);

                }

            }

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

                m.pos(*v) = new_pos[*v];

        }

        VertexAttributeVector<int> vtouched(m.total_vertices(), 0);

        i = 0;

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

            ofs << "vt " << (0.5*m.pos(*v)[0]+0.5) << " " << (0.5*m.pos(*v)[1]+0.5)  << endl;

            vtouched[*v] = i;

        }

        ofs << endl;

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

            ofs << "f ";

            for(HalfEdgeWalker w = m.halfedgewalker(*f); !w.full_circle(); w = w.circulate_face_cw()){

                int idx = vtouched[w.vertex()] + 1;

                ofs << idx << "/" << idx <<" ";

            }

            ofs << endl;

        }

    }

}