LOD_QuadricEditor.cpp

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/*
 * ***** BEGIN GPL LICENSE BLOCK *****
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * 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 for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 * The Original Code is Copyright (C) 2001-2002 by NaN Holding BV.
 * All rights reserved.
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 * The Original Code is: all of this file.
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 * ***** END GPL LICENSE BLOCK *****
 */

#include "LOD_QuadricEditor.h"
#include "LOD_ExternNormalEditor.h"

// Creation

using namespace std;


LOD_QuadricEditor::
LOD_QuadricEditor(
    LOD_ManMesh2 &mesh
) :
    m_quadrics(NULL),
    m_mesh(mesh)
{
};

    LOD_QuadricEditor *
LOD_QuadricEditor::
New(
    LOD_ManMesh2 &mesh
){
    //same number of quadrics as vertices in the mesh

    MEM_SmartPtr<LOD_QuadricEditor> output(new LOD_QuadricEditor(mesh));

    if (output == NULL) {
        return NULL;
    }
    return output.Release();
}


// Property editor interface

    void
LOD_QuadricEditor::
Remove(
    std::vector<LOD_VertexInd> &sorted_vertices
){
    vector<LOD_Quadric> & quadrics = *m_quadrics;

    vector<LOD_VertexInd>::const_iterator it_start = sorted_vertices.begin();
    vector<LOD_VertexInd>::const_iterator it_end = sorted_vertices.end();

    for (; it_start != it_end; ++it_start) {

        if (quadrics.size() > 0) {
            LOD_Quadric temp = quadrics[*it_start];
        
            quadrics[*it_start] = quadrics.back();
            quadrics.back() = temp;

            quadrics.pop_back();
        }
    }
};


// Editor specific methods

    bool
LOD_QuadricEditor::
BuildQuadrics(
    LOD_ExternNormalEditor& normal_editor,
    bool preserve_boundaries
){
    if (m_quadrics != NULL) delete(m_quadrics);     

    m_quadrics =new vector<LOD_Quadric> (m_mesh.VertexSet().size());
    if (m_quadrics == NULL) return false;

    // iterate through the face set of the mesh
    // compute a quadric based upon that face and 
    // add it to each of it's vertices quadrics.

    const vector<LOD_TriFace> &faces = m_mesh.FaceSet();
    const vector<LOD_Vertex> &verts = m_mesh.VertexSet();
    vector<LOD_Edge> &edges = m_mesh.EdgeSet(); 

    const vector<MT_Vector3> &normals = normal_editor.Normals();
    vector<MT_Vector3>::const_iterator normal_it = normals.begin();
    
    vector<LOD_TriFace>::const_iterator face_it = faces.begin();
    vector<LOD_TriFace>::const_iterator face_end = faces.end();

    vector<LOD_Quadric> & quadrics = *m_quadrics;


    for (; face_it != face_end; ++face_it, ++normal_it) {
                
        MT_Vector3 normal = *normal_it;
        MT_Scalar offset = -normal.dot(verts[face_it->m_verts[0]].pos); 

        LOD_Quadric q(normal,offset);

        quadrics[face_it->m_verts[0]] += q;
        quadrics[face_it->m_verts[1]] += q;
        quadrics[face_it->m_verts[2]] += q;
    }

    if (preserve_boundaries) {

        // iterate through the edge set and add a boundary quadric to 
        // each of the boundary edges vertices.
    
        vector<LOD_Edge>::const_iterator edge_it = edges.begin();
        vector<LOD_Edge>::const_iterator edge_end = edges.end();    

        for (; edge_it != edge_end; ++edge_it) {
            if (edge_it->BoundaryEdge()) {

                // compute a plane perpendicular to the edge and the normal
                // of the edges single polygon.
                const MT_Vector3 & v0 = verts[edge_it->m_verts[0]].pos;
                const MT_Vector3 & v1 = verts[edge_it->m_verts[1]].pos;
    
                MT_Vector3 edge_vector = v1 - v0;

                LOD_FaceInd edge_face = edge_it->OpFace(LOD_EdgeInd::Empty());
                edge_vector = edge_vector.cross(normals[edge_face]);

                if (!edge_vector.fuzzyZero()) {
                    edge_vector.normalize();
                
                    LOD_Quadric boundary_q(edge_vector, - edge_vector.dot(v0)); 
                    boundary_q *= 100;              

                    quadrics[edge_it->m_verts[0]] += boundary_q;
                    quadrics[edge_it->m_verts[1]] += boundary_q;
                }
            }
        }
    }


    // initiate the heap keys of the edges by computing the edge costs.

    vector<LOD_Edge>::iterator edge_it = edges.begin();
    vector<LOD_Edge>::const_iterator edge_end = edges.end();

    for (; edge_it != edge_end; ++edge_it)  {
        
        MT_Vector3 target = TargetVertex(*edge_it);

        LOD_Edge &e = *edge_it;
        LOD_Quadric q0 = quadrics[e.m_verts[0]];
        const LOD_Quadric &q1 = quadrics[e.m_verts[1]];
        
        e.HeapKey() = -float(q0.Evaluate(target) + q1.Evaluate(target));
    }

    return true;

};

    MT_Vector3 
LOD_QuadricEditor::
TargetVertex(
    LOD_Edge & e
){

    // compute an edge contration target for edge ei
    // this is computed by summing it's vertices quadrics and 
    // optimizing the result.
    vector<LOD_Vertex> &verts = m_mesh.VertexSet();

    vector<LOD_Quadric> &quadrics = *m_quadrics;

    LOD_VertexInd v0 = e.m_verts[0];
    LOD_VertexInd v1 = e.m_verts[1];

    LOD_Quadric q0 = quadrics[v0];
    q0 += quadrics[v1];

    MT_Vector3 result;

    if (q0.Optimize(result)) {
        return result;
    } else {
        // the quadric was degenerate -> just take the average of 
        // v0 and v1

        return ((verts[v0].pos + verts[v1].pos) * 0.5);
    }
};

    void
LOD_QuadricEditor::
ComputeEdgeCosts(
    vector<LOD_EdgeInd> &edges
){  
    
    // for each we compute the target vertex and then compute
    // the quadric error e = Q1(v') + Q2(v')
    vector<LOD_Edge> &edge_set = m_mesh.EdgeSet();

    vector<LOD_Quadric> &quadrics = *m_quadrics;

    vector<LOD_EdgeInd>::const_iterator edge_it = edges.begin();
    vector<LOD_EdgeInd>::const_iterator edge_end = edges.end();

    for (; edge_it != edge_end; ++edge_it)  {
        
        MT_Vector3 target = TargetVertex(edge_set[*edge_it]);

        LOD_Edge &e = edge_set[*edge_it];
        LOD_Quadric q0 = quadrics[e.m_verts[0]];
        const LOD_Quadric &q1 = quadrics[e.m_verts[1]];
        
        e.HeapKey() = -float(q0.Evaluate(target) + q1.Evaluate(target));
    }
};