ShadowVolumeGen.cpp

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// Copyright (C) 2005 Dave Griffiths
//
// 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.

#include <algorithm>
#include "ShadowVolumeGen.h"

using namespace Fluxus;

ShadowVolumeGen::ShadowVolumeGen() :
m_ShadowVolume(PolyPrimitive::QUADS),
m_LightPosition(5,5,0),
m_Length(10),
m_Debug(false)
{
}

ShadowVolumeGen::~ShadowVolumeGen() 
{
}

void ShadowVolumeGen::Generate(Primitive *prim)
{   
    PolyPrimitive *poly = dynamic_cast<PolyPrimitive*>(prim);
    if (poly)
    {
        PolyGen(poly);
    }
    else
    {       
        NURBSPrimitive *nurbs = dynamic_cast<NURBSPrimitive*>(prim);
        if (nurbs)
        {
            NURBSGen(nurbs);
        }
    }
}

void ShadowVolumeGen::Clear()
{ 
    m_ShadowVolume.Resize(0);
}

PolyPrimitive *ShadowVolumeGen::GetVolume() 
{ 
    return &m_ShadowVolume; 
}

void ShadowVolumeGen::PolyGen(PolyPrimitive *src)
{   
    TypedPData<dVector> *points = dynamic_cast<TypedPData<dVector>* >(src->GetDataRaw("p"));
    
    const vector<dVector> &normals = src->GetGeometricNormals();
    const vector<vector<int> > &connected=src->GetConnectedVerts();
    
    dMatrix &transform = src->GetState()->Transform;
    
    int stride=0;
    if (src->GetType()==PolyPrimitive::TRISTRIP) stride=2;
    if (src->GetType()==PolyPrimitive::QUADS) stride=4;
    if (src->GetType()==PolyPrimitive::TRILIST) stride=3;
    if (stride>0)
    {
        SharedEdgeContainer edges = src->GetUniqueEdges();
        vector<pair<dVector,dVector> > silhouette;
            
        if (src->IsIndexed())
        {
            vector<unsigned int> index = src->GetIndex();
            // loop over all the edges
            for (SharedEdgeContainer::iterator i=edges.begin(); i!=edges.end(); ++i)
            {
                EdgeContainer sharededges = *i;

                dVector lightdir = transform.transform(points->m_Data[index[sharededges.begin()->first]])-m_LightPosition;
                lightdir.normalise();

                if (sharededges.size()==2)
                {
                    bool backface=false;
                    bool frontface=false;

                    EdgeContainer::iterator frontedge;

                    // loop over the edges shared by this one
                    for (EdgeContainer::iterator edge=sharededges.begin(); edge!=sharededges.end(); ++edge)
                    {           
                        // only check the first vert, as they should have 
                        // the same geometric normal if the poly is planar..
                        if (lightdir.dot(transform.transform_no_trans(normals[edge->first]))>0) 
                        {
                            frontedge=edge;
                            frontface=true;
                        }
                        else backface=true;
                    }

                    // if we contain both front and back facing normals (from the light's pov) 
                    if (backface && frontface) 
                    {           
                        silhouette.push_back(pair<dVector,dVector>(transform.transform(points->m_Data[index[frontedge->first]]),
                                                                   transform.transform(points->m_Data[index[frontedge->second]])));
                    }
                }
            }
        }
        else
        {
            // loop over all the edges
            for (SharedEdgeContainer::iterator i=edges.begin(); i!=edges.end(); ++i)
            {
                EdgeContainer sharededges = *i;

                dVector lightdir = transform.transform(points->m_Data[sharededges.begin()->first])-m_LightPosition;
                lightdir.normalise();


                if (sharededges.size()==2)
                {
                    bool backface=false;
                    bool frontface=false;

                    EdgeContainer::iterator frontedge;

                    // loop over the edges shared by this one
                    for (EdgeContainer::iterator edge=sharededges.begin(); edge!=sharededges.end(); ++edge)
                    {           
                        // only check the first vert, as they should have 
                        // the same geometric normal if the poly is planar..
                        if (lightdir.dot(transform.transform_no_trans(normals[edge->first]))>0) 
                        {
                            frontedge=edge;
                            frontface=true;
                        }
                        else backface=true;
                    }

                    // if we contain both front and back facing normals (from the light's pov) 
                    if (backface && frontface) 
                    {           
                        silhouette.push_back(pair<dVector,dVector>(transform.transform(points->m_Data[frontedge->first]),
                                                                   transform.transform(points->m_Data[frontedge->second])));
                    }
                }
            }
        }
        
        for (vector<pair<dVector,dVector> >::iterator i=silhouette.begin();
             i!=silhouette.end(); i++)
        {
            AddEdge(i->first,i->second);
        }
    }
}

void ShadowVolumeGen::AddEdge(dVector start, dVector end)
{
    if (m_Debug)
    {
        glDisable(GL_LIGHTING);
        glLineWidth(3);
        glBegin(GL_LINES);                  
            glColor3f(1,0,0);
            glVertex3fv(start.arr());
            glColor3f(0,0,1);
            glVertex3fv(end.arr());
        glEnd();
        glEnable(GL_LIGHTING);
    }

    m_ShadowVolume.AddVertex(dVertex(start,dVector(0,0,0),0,0));
    m_ShadowVolume.AddVertex(dVertex(end,dVector(0,0,0),0,0));

    dVector proj = end-m_LightPosition;
    m_ShadowVolume.AddVertex(dVertex(end+proj*m_Length,dVector(0,0,0),0,0));

    proj = start-m_LightPosition;
    m_ShadowVolume.AddVertex(dVertex(start+proj*m_Length,dVector(0,0,0),0,0));
}

void ShadowVolumeGen::NURBSGen(NURBSPrimitive *src)
{   
    TypedPData<dVector> *points = dynamic_cast<TypedPData<dVector>* >(src->GetDataRaw("p"));
    TypedPData<dVector> *normals = dynamic_cast<TypedPData<dVector>* >(src->GetDataRaw("n"));
    
    dMatrix &transform = src->GetState()->Transform;
    
    int stride=4;
    
    // loop over all the faces
    for (unsigned int vert=0; vert<points->Size(); vert+=stride)
    {
        // find out if we are on an edge or not
        vector<int> edgeverts;

        for (int facevert=0; facevert<stride; facevert++)
        {
            dVector lightdir = transform.transform(points->m_Data[vert+facevert])-m_LightPosition;
            lightdir.normalise();

            bool backface=false;
            bool frontface=false;

            
            // loop over the verts connected to this one
            /*for (vector<int>::const_iterator cv=connected[vert+facevert].begin(); 
                cv!=connected[vert+facevert].end(); cv++)
            {           
                if (lightdir.dot(transform.transform_no_trans(normals->m_Data[*cv]))>0) frontface=true;
                else backface=true;
            }*/
            
            // if we contain both front and back facing normals (from the light's pov) 
            if (backface && frontface) 
            {
                edgeverts.push_back(vert+facevert);
            }
        }

        if (edgeverts.size()>=2)
        {
            for (unsigned int i=0; i<edgeverts.size()-1; i++)
            {   
                dVector worldpoint1 = transform.transform(points->m_Data[edgeverts[i]]);
                dVector worldpoint2 = transform.transform(points->m_Data[edgeverts[i+1]]);

                glPushMatrix();
                glDisable(GL_LIGHTING);
                glBegin(GL_LINES);                  
                    glColor3f(1,0,0);
                    glVertex3fv(worldpoint1.arr());
                    glColor3f(0,0,1);
                    glVertex3fv(worldpoint2.arr());
                glEnd();
                glEnable(GL_LIGHTING);
                glPopMatrix();

                m_ShadowVolume.AddVertex(dVertex(worldpoint1,dVector(0,0,0),0,0));
                m_ShadowVolume.AddVertex(dVertex(worldpoint2,dVector(0,0,0),0,0));

                dVector proj = worldpoint2-m_LightPosition;
                m_ShadowVolume.AddVertex(dVertex(worldpoint1+proj*100,dVector(0,0,0),0,0));

                proj = worldpoint1-m_LightPosition;
                m_ShadowVolume.AddVertex(dVertex(worldpoint2+proj*100,dVector(0,0,0),0,0));
            }
        }
    }
}

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