LOD_QSDecimator.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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 * ***** END GPL LICENSE BLOCK *****
 */

#include "LOD_QSDecimator.h"

#include "LOD_ExternBufferEditor.h"

using namespace std;

    LOD_QSDecimator *
LOD_QSDecimator::
New(
    LOD_ManMesh2 &mesh,
    LOD_ExternNormalEditor &face_editor,
    LOD_ExternBufferEditor &extern_editor
){

    MEM_SmartPtr<LOD_QSDecimator> output 
        = new LOD_QSDecimator(mesh,face_editor,extern_editor);

    MEM_SmartPtr<LOD_EdgeCollapser > collapser(LOD_EdgeCollapser::New());
    MEM_SmartPtr<LOD_QuadricEditor> q_editor(LOD_QuadricEditor::New(mesh));

    if (
        output == NULL ||
        collapser == NULL ||
        q_editor == NULL 
    ) {
        return NULL;
    }
    output->m_collapser = collapser.Release();
    output->m_quadric_editor = q_editor.Release();
    return output.Release();
}   



    bool
LOD_QSDecimator::
Arm(
){
    MT_assert(!m_is_armed);
    bool heap_result = BuildHeap();
    if (!heap_result) {
        return false;
    }
    m_is_armed = true;
    return true;
}
    
    bool
LOD_QSDecimator::
Step(
){
    return CollapseEdge();
}


LOD_QSDecimator::
LOD_QSDecimator(
    LOD_ManMesh2 &mesh,
    LOD_ExternNormalEditor &face_editor,
    LOD_ExternBufferEditor &extern_editor
) :
    m_is_armed (false),
    m_mesh(mesh),
    m_face_editor(face_editor),
    m_extern_editor(extern_editor)
{   
    m_deg_edges.reserve(32);
    m_deg_faces.reserve(32);
    m_deg_vertices.reserve(32);
    m_update_faces.reserve(32);
    m_new_edges.reserve(32);
    m_update_vertices.reserve(32);
};

    bool
LOD_QSDecimator::
CollapseEdge(
){
    
    // find an edge to collapse
    
    // FIXME force an edge collapse
    // or return false

    std::vector<LOD_Edge> & edges = m_mesh.EdgeSet();
    std::vector<LOD_Vertex> & verts = m_mesh.VertexSet();
    std::vector<LOD_Quadric> & quadrics = m_quadric_editor->Quadrics();
    int size = edges.size();

    if (size == 0) return false;

    const int heap_top = m_heap->Top();

    if (heap_top == -1 || edges[heap_top].HeapKey() <= -MT_INFINITY) {
        return false;
    }
    
    // compute the target position
    MT_Vector3 new_vertex = m_quadric_editor->TargetVertex(edges[heap_top]);
    LOD_Quadric & q0 = quadrics[edges[heap_top].m_verts[0]];
    LOD_Quadric & q1 = quadrics[edges[heap_top].m_verts[1]];

    LOD_Vertex &v0 = verts[edges[heap_top].m_verts[0]];
    LOD_Vertex &v1 = verts[edges[heap_top].m_verts[1]];

    LOD_Quadric sum = q0;
    sum += q1;


    if (m_collapser->CollapseEdge(
            heap_top,
            m_mesh,
            m_deg_edges,
            m_deg_faces,
            m_deg_vertices,
            m_new_edges,
            m_update_faces,
            m_update_vertices
    )) {

        // assign new vertex position

        v0.pos = new_vertex;
        v1.pos = new_vertex;

        // sum the quadrics of v0 and v1
        q0 = sum;
        q1 = sum;

        // ok update the primitive properties

        m_face_editor.Update(m_update_faces);   
        m_face_editor.UpdateVertexNormals(m_update_vertices);

        // update the external vertex buffer 
        m_extern_editor.CopyModifiedVerts(m_mesh,m_update_vertices);

        // update the external face buffer
        m_extern_editor.CopyModifiedFaces(m_mesh,m_update_faces);

        // update the edge heap
        UpdateHeap(m_deg_edges,m_new_edges);

        m_quadric_editor->Remove(m_deg_vertices);
        m_face_editor.Remove(m_deg_faces);
        m_face_editor.RemoveVertexNormals(m_deg_vertices);      
                
        // delete the primitives

        DeletePrimitives(m_deg_edges,m_deg_faces,m_deg_vertices);

    } else {
        // the edge could not be collapsed at the moment - so
        // we adjust it's priority and add it back to the heap.
        m_heap->Remove(&edges[0],0);
        edges[heap_top].HeapKey() = - MT_INFINITY;
        m_heap->Insert(&edges[0],heap_top);
    }

    //clear all the temporary buffers

    m_deg_faces.clear();
    m_deg_edges.clear();
    m_deg_vertices.clear();
    
    m_update_faces.clear();
    m_update_vertices.clear();
    m_new_edges.clear();

    return true;

}   

    void
LOD_QSDecimator::
DeletePrimitives(
    const vector<LOD_EdgeInd> & degenerate_edges,
    const vector<LOD_FaceInd> & degenerate_faces,
    const vector<LOD_VertexInd> & degenerate_vertices
) {

    // assumes that the 3 vectors are sorted in descending order.

    // Delete Degnerate primitives


    // delete the old edges - we have to be very careful here
    // mesh.delete() swaps edges to be deleted with the last edge in 
    // the edge buffer. However the next edge to be deleted may have
    // been the last edge in the buffer!

    // One way to solve this is to sort degenerate_edges in descending order.
    // And then delete them in that order.
    
    // it is also vital that degenerate_edges contains no duplicates

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

    for (; edge_it != edge_end; ++edge_it) {
        m_mesh.DeleteEdge(*edge_it,m_heap);
    }



    vector<LOD_FaceInd>::const_iterator face_it = degenerate_faces.begin();
    vector<LOD_FaceInd>::const_iterator face_end = degenerate_faces.end();
    
    for (;face_it != face_end; ++face_it) {
        m_mesh.DeleteFace(m_extern_editor,*face_it);
    }

    vector<LOD_VertexInd>::const_iterator vertex_it = degenerate_vertices.begin();
    vector<LOD_VertexInd>::const_iterator vertex_end = degenerate_vertices.end();
    
    for (;vertex_it != vertex_end; ++vertex_it) {
        m_mesh.DeleteVertex(m_extern_editor,*vertex_it);
    }
}


    bool
LOD_QSDecimator::
BuildHeap(
){
    // build the quadrics 

    if (m_quadric_editor->BuildQuadrics(m_face_editor,true) == false) return false;


    m_heap = CTR_UHeap<LOD_Edge>::New();
    // load in edge pointers to the heap

    std::vector<LOD_Edge> & edge_set= m_mesh.EdgeSet();
    std::vector<LOD_Edge>::const_iterator edge_end = edge_set.end();
    std::vector<LOD_Edge>::iterator edge_start = edge_set.begin();

    std::vector<int> & heap_vector = m_heap->HeapVector();

    for (unsigned int i = 0; i < edge_set.size(); ++i) {
        edge_set[i].HeapPos() = i;
        heap_vector.push_back(i);
    }
    
    m_heap->MakeHeap(&edge_set[0]);

    return true;
}

    void
LOD_QSDecimator::
UpdateHeap(
    std::vector<LOD_EdgeInd> &deg_edges,
    std::vector<LOD_EdgeInd> &new_edges
){
    // first of all compute values for the new edges 
    // and bung them on the heap.

    std::vector<LOD_Edge>  & edge_set= m_mesh.EdgeSet();

    std::vector<LOD_EdgeInd>::const_iterator edge_it = new_edges.begin();
    std::vector<LOD_EdgeInd>::const_iterator end_it = new_edges.end();


    // insert all the new edges     

    // compute edge costs ffor the new edges

    m_quadric_editor->ComputeEdgeCosts(new_edges);

    // inser the new elements into the heap

    for (; edge_it != end_it; ++edge_it) {      
        m_heap->Insert(&edge_set[0],*edge_it);
    }


    // remove all the old values from the heap

    edge_it = deg_edges.begin();
    end_it = deg_edges.end();

    for (; edge_it != end_it; ++edge_it) {
        LOD_Edge &e = edge_set[*edge_it];
        m_heap->Remove(&edge_set[0],e.HeapPos());

        e.HeapPos() = -1;

    }
}