source: GTP/trunk/Lib/Vis/Preprocessing/src/GlRenderer.cpp @ 2743

#include "Mesh.h"
#include "glInterface.h"
#include "OcclusionQuery.h"
#include "GlRenderer.h"
#include "ViewCellsManager.h"
#include "SceneGraph.h"
#include "ViewCell.h"
#include "Beam.h"
#include "KdTree.h"
#include "Environment.h"
#include "Triangle3.h"
#include "IntersectableWrapper.h"
#include "BvHierarchy.h"
#include "KdTree.h"
#include "SamplingStrategy.h"
#include "Preprocessor.h"
#include "SceneGraph.h"


#ifdef USE_CG

#include <Cg/cg.h>
#include <Cg/cgGL.h>

#endif

// if 1 = SAFE RENDERING OF PVS primitives without VBOs for Pvs error estimation
#define EVAL_ERROR 0

namespace GtpVisibilityPreprocessor {


static bool arbQuerySupport = false;
static bool nvQuerySupport = false;

static GLuint frontDepthMap;
static GLuint backDepthMap;

const int depthMapSize = 512;


static void InitExtensions() 
{
        GLenum err = glewInit();

        if (GLEW_OK != err) 
        {
                // problem: glewInit failed, something is seriously wrong
                cerr << "Error: " << glewGetErrorString(err) << endl;
                exit(1);
        }

        if (GLEW_ARB_occlusion_query) 
                arbQuerySupport = true;
        
        if (GLEW_NV_occlusion_query) 
                nvQuerySupport = true;

        if  (!arbQuerySupport && !nvQuerySupport)
        {
                cout << "I require the GL_ARB_occlusion_query or the GL_NV_occlusion_query OpenGL extension to work.\n";
                exit(1);
        }

        if (!GLEW_ARB_vertex_buffer_object) 
        {
                cout << "vbos not supported" << endl;
        }
        else
        {
                cout << "vbos supported" << endl;
        }
}


GlRenderer::GlRenderer(SceneGraph *sceneGraph,
                                           ViewCellsManager *viewCellsManager,
                                           KdTree *tree):
Renderer(sceneGraph, viewCellsManager),
mKdTree(tree),
mUseFalseColors(false),
mVboId(-1),
mData(NULL),
mIndices(NULL),
mComputeGVS(false),
mCurrentFrame(100)
{
        mSceneGraph->CollectObjects(mObjects);

        if (0)
        {
                viewCellsManager->GetViewPoint(mViewPoint);
                mViewDirection = Vector3(0,0,1);
        }
        else
        {

                // for sg snapshot
                mViewPoint = Vector3(32.8596, 9.86079, -1023.79);
                mViewDirection = Vector3(-0.92196, 0, 0.387286);

                // inside
                mViewPoint = Vector3(14.1254, 10.9818, -1032.75);
                mViewDirection = Vector3(-0.604798, 0, 0.796379);

                if (1) {

                        // outside
                        mViewPoint = Vector3(35.092, 17.7078, -857.966);
                        mViewDirection = Vector3(-0.411287, 0, -0.911506);

                        // strange viewcell for error measurements (id 534)
                        mViewPoint = Vector3(1405.9, 218.284, -736.785);
                        mViewDirection = Vector3(0.989155, 0, 0.146877);

                        // high error for city_full
                        mViewPoint = Vector3(842.521, 194.708, -136.708);
                        mViewDirection = Vector3(0.730514, 0, -0.682897);

                        // also high error for city_full
                        mViewPoint = Vector3(1038.7f, 192.4f, -471.0f);
                        mViewDirection = Vector3(-0.8f, 0.0f, -0.6f);

                        mViewPoint = Vector3(440.295, 196.959, -781.302);
                        mViewDirection = Vector3(-0.0566328, 0, -0.998395);

                        mViewPoint = Vector3(680.682, 189.552, -278.177);
                        mViewDirection = Vector3(0.942709, -0, -0.333584);

                        // strange error for gvs
                        /*mViewPoint = Vector3(1186.9, 193.552, -377.044);
                        mViewDirection = Vector3(-0.963031, -0, -0.269365);

                        mViewPoint = Vector3(1189.54, 220.087, -462.869);
                        mViewDirection = Vector3(-0.996972, -0, -0.0776569);

                        mViewPoint = Vector3(1199.53, 257.677, -457.145);
                        mViewDirection = Vector3(-0.71206, -0, -0.702108);

                        mViewPoint = Vector3(1188.22, 187.427, -381.739);
                        mViewDirection = Vector3(-0.963031, -0, -0.269365);

                        mViewPoint = Vector3(1188.22, 187.427, -381.739);
                        mViewDirection = Vector3(-0.963031, -0, -0.269365);
*/
                }
        }

        mFrame = 0;
        mWireFrame = false;
        Environment::GetSingleton()->GetBoolValue("Preprocessor.detectEmptyViewSpace",
                                                      mDetectEmptyViewSpace);

        Environment::GetSingleton()->GetBoolValue("Preprocessor.snapErrorFrames",
                                                      mSnapErrorFrames);

        mSnapPrefix = "snap/";
        mUseForcedColors = false;
        mRenderBoxes = false;
        //mUseGlLists = true;
        mUseGlLists = false;

        Environment::GetSingleton()->GetBoolValue("Preprocessor.useVbos", mUseVbos);

        if (mViewCellsManager->GetViewCellPointsList()->size())
                mPvsStatFrames = (int)mViewCellsManager->GetViewCellPointsList()->size();
        else
                Environment::GetSingleton()->GetIntValue("Preprocessor.pvsRenderErrorSamples",
                                                                                                 mPvsStatFrames);
        
        Debug<<"Info: will evaluate pixel error with "<<mPvsStatFrames<<" samples"<<endl;
        
        mPvsErrorBuffer.resize(mPvsStatFrames);
        ClearErrorBuffer();
}


GlRenderer::~GlRenderer()
{
        cerr<<"gl renderer destructor..\n";

        CLEAR_CONTAINER(mOcclusionQueries);

        DeleteVbos();

        if (mData) delete [] mData;
        if (mIndices) delete [] mIndices;

        glDeleteBuffersARB(1, &mVboId);
        cerr<<"done."<<endl;
}


void GlRenderer::RenderTriangle(TriangleIntersectable *object)
{
        Triangle3 *t = &(object->GetItem());
        glBegin(GL_TRIANGLES);
        Vector3 normal = t->GetNormal();
        glNormal3f(normal.x, normal.y, normal.z);
        glVertex3f(t->mVertices[0].x, t->mVertices[0].y, t->mVertices[0].z);
        glVertex3f(t->mVertices[1].x, t->mVertices[1].y, t->mVertices[1].z);
        glVertex3f(t->mVertices[2].x, t->mVertices[2].y, t->mVertices[2].z);
        glEnd();
}


void GlRenderer::RenderIntersectable(Intersectable *object)
{
  if (!object || (object->mRenderedFrame == mCurrentFrame))
        return;

        object->mRenderedFrame = mCurrentFrame;

        glPushAttrib(GL_CURRENT_BIT);

        if (mUseFalseColors) SetupFalseColor(object->mId);

        switch (object->Type()) 
        {
        case Intersectable::MESH_INSTANCE:
                RenderMeshInstance((MeshInstance *)object);
                break;
        case Intersectable::VIEW_CELL:
                RenderViewCell(static_cast<ViewCell *>(object));
                break;
        case Intersectable::TRANSFORMED_MESH_INSTANCE:
                RenderTransformedMeshInstance(static_cast<TransformedMeshInstance *>(object));
                break;
        case Intersectable::TRIANGLE_INTERSECTABLE:
                RenderTriangle(static_cast<TriangleIntersectable *>(object));
                break;
        case Intersectable::BVH_INTERSECTABLE: 
                {
                        BvhNode *node = static_cast<BvhNode *>(object);

                        if (mRenderBoxes)
                                RenderBox(node->GetBoundingBox());
                        else
                                RenderBvhNode(node);
                        break;
                }
        case Intersectable::KD_INTERSECTABLE: 
                {
                        KdNode *node = (static_cast<KdIntersectable *>(object))->GetItem();

                        if (mRenderBoxes)
                                RenderBox(mKdTree->GetBox(node));
                        else
                                RenderKdNode(node);
                        break;
                }

        default:
                cerr<<"Rendering this object not yet implemented\n";
                break;
        }

        glPopAttrib();
}


void GlRenderer::RenderRays(const VssRayContainer &rays, int colorType, int showDistribution, int maxAge)
{
        float importance;

        glBegin(GL_LINES);

        VssRayContainer::const_iterator it = rays.begin(), it_end = rays.end();

        for (; it != it_end; ++it) 
        {
                VssRay *ray = *it;

                // only show distributions that were checked
                if (((ray->mDistribution == SamplingStrategy::DIRECTION_BASED_DISTRIBUTION) && ((showDistribution & 1) == 0)) ||
                        ((ray->mDistribution == SamplingStrategy::SPATIAL_BOX_BASED_DISTRIBUTION) && ((showDistribution & 2) == 0)) ||
                        ((ray->mDistribution == SamplingStrategy::OBJECT_DIRECTION_BASED_DISTRIBUTION) && ((showDistribution & 4) == 0)) ||
                        ((ray->mDistribution == SamplingStrategy::MUTATION_BASED_DISTRIBUTION) && ((showDistribution & 8) == 0)) ||
                        ((mViewCellsManager->GetPreprocessor()->mPass - ray->mPass) >= maxAge))
                {
                        continue;
                }
                
                switch (colorType)
                {
                case 0:
                        glColor3f(1.0f, 0.0f, 0.0f);
                        break;

                case 1:
                        importance = 1.0f * ray->Length() /  Magnitude(mViewCellsManager->GetViewSpaceBox().Diagonal());
                        glColor3f(importance, importance, importance);
                        break;

                case 2:
                        importance = log10(1e3 * ray->mPvsContribution) / 3.0f;
                        glColor3f(importance, importance, importance);
                        break;

                case 3:
                        {
                                // nested switches ok?
                                switch (ray->mDistribution)
                                {
                                case SamplingStrategy::SPATIAL_BOX_BASED_DISTRIBUTION:
                                        glColor3f(1, 0, 0);
                                        break;
                                case SamplingStrategy::MUTATION_BASED_DISTRIBUTION:
                                        glColor3f(0, 1, 0);
                                        break;
                                case SamplingStrategy::DIRECTION_BASED_DISTRIBUTION:
                                        glColor3f(0, 1, 1);
                                        break;
                                        case SamplingStrategy::OBJECT_DIRECTION_BASED_DISTRIBUTION:
                                        glColor3f(1, 1, 0);
                                        break;
                                }
                        }
                }               

                glVertex3fv(&ray->mOrigin.x);
                glVertex3fv(&ray->mTermination.x);
        }

        glEnd();
}


void GlRenderer::RenderViewCell(ViewCell *vc)
{
        if (vc->GetMesh()) 
        {
                if (!mUseFalseColors) 
                {
                        if (vc->GetValid()) 
                                glColor3f(0,1,0);
                        else
                                glColor3f(0,0,1);
                }

                RenderMesh(vc->GetMesh());
        } 
        else 
        {
                // render viewcells in the subtree
                if (!vc->IsLeaf()) 
                {
                        ViewCellInterior *vci = (ViewCellInterior *) vc;

                        ViewCellContainer::iterator it = vci->mChildren.begin();
                        for (; it != vci->mChildren.end(); ++it) 
                        {
                                RenderViewCell(*it);
                        }
                } 
                else 
                {
                        // cerr<<"Empty viewcell mesh\n";
                }
        }
}


void GlRenderer::RenderMeshInstance(MeshInstance *mi)
{
        RenderMesh(mi->GetMesh());
}


void
GlRenderer::RenderTransformedMeshInstance(TransformedMeshInstance *mi)
{
        // apply world transform before rendering
        Matrix4x4 m;
        mi->GetWorldTransform(m);

        glPushMatrix();
        glMultMatrixf((float *)m.x);

        RenderMesh(mi->GetMesh());
        
        glPopMatrix();
}


void
GlRenderer::SetupFalseColor(const unsigned int id)
{
        // swap bits of the color
        glColor3ub(id&255, (id>>8)&255, (id>>16)&255);
}


unsigned int GlRenderer::GetId(const unsigned char r, 
                                                           const unsigned char g, 
                                                           const unsigned char b) const
{
        return r + (g << 8) + (b << 16);
}


void
GlRenderer::SetupMaterial(Material *m)
{
  if (m)
        glColor3fv(&(m->mDiffuseColor.r));
}


void GlRenderer::RenderMesh(Mesh *mesh)
{
        int i = 0;

        if (!mUseFalseColors && !mUseForcedColors)
                SetupMaterial(mesh->mMaterial);

        for (i = 0; i < mesh->mFaces.size(); i++) 
        {
                if (mWireFrame)
                        glBegin(GL_LINE_LOOP);
                else
                        glBegin(GL_POLYGON);

                Face *face = mesh->mFaces[i];
                Vector3 normal = mesh->GetNormal(i);

                glNormal3f(normal.x, normal.y, normal.z);
                for (int j = 0; j < face->mVertexIndices.size(); j++) {
                        glVertex3fv(&mesh->mVertices[face->mVertexIndices[j]].x);
                }
                glEnd();
        }
}

        
void GlRenderer::InitGL()
{
        mSphere = (GLUquadric *)gluNewQuadric();

        glMatrixMode(GL_PROJECTION);
        glLoadIdentity();

        glMatrixMode(GL_MODELVIEW);
        glLoadIdentity();

        glFrontFace(GL_CCW);
        glCullFace(GL_BACK);

        glShadeModel(GL_FLAT);
        glDepthFunc(GL_LESS );
        glEnable(GL_DEPTH_TEST);
        glEnable(GL_CULL_FACE);

        InitExtensions();

        glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);
        glEnable(GL_NORMALIZE);
        glClearColor(0.0f, 0.0f, 0.0f, 1.0f);

        // create some occlusion queries
        OcclusionQuery::GenQueries(mOcclusionQueries, 100);

        SceneGraphInterior *interior = mSceneGraph->GetRoot();

        SceneGraphNodeContainer::iterator ni = interior->mChildren.begin();

        for (; ni != interior->mChildren.end(); ni++) 
                CreateVertexArrays(static_cast<SceneGraphLeaf *>(*ni));
}


void
GlRenderer::SetupProjection(const int w, const int h, const float angle)
{
        glViewport(0, 0, w, h);
        glMatrixMode(GL_PROJECTION);
        glLoadIdentity();
        gluPerspective(angle, 1.0, 1.0f, 2.0 * Magnitude(mSceneGraph->GetBox().Diagonal()));
        glMatrixMode(GL_MODELVIEW);
}



void
GlRenderer::SetupCamera()
{
        Vector3 target = mViewPoint + mViewDirection;

        Vector3 up(0,1,0);

        if (fabs(DotProd(mViewDirection, up)) > 0.99f)
          up = Vector3(1, 0, 0);

        glLoadIdentity();
        gluLookAt(mViewPoint.x, mViewPoint.y, mViewPoint.z,
                target.x, target.y, target.z,
                up.x, up.y, up.z);
}


void GlRenderer::_RenderScene()
{
        ObjectContainer::const_iterator oi = mObjects.begin();

        for (; oi != mObjects.end(); oi++)
                RenderIntersectable(*oi);
}


void GlRenderer::_RenderSceneTrianglesWithDrawArrays()
{
        EnableDrawArrays();
        
        if (mUseVbos)
                glBindBufferARB(GL_ARRAY_BUFFER_ARB, mVboId);

        const int offset = (int)mObjects.size() * 3;
        char *arrayPtr = mUseVbos ? NULL : (char *)mData;
        
        glVertexPointer(3, GL_FLOAT, 0, (char *)arrayPtr);
        glNormalPointer(GL_FLOAT, 0, (char *)arrayPtr + offset * sizeof(Vector3));
        
        glDrawArrays(GL_TRIANGLES, 0, offset);
}


void GlRenderer::_RenderDynamicObject(SceneGraphLeaf *leaf)
{
        // apply world transform before rendering
        Matrix4x4 m;
        leaf->GetTransform(m);

        glPushMatrix();
        glMultMatrixf((float *)m.x);

        glBegin(GL_TRIANGLES);

        ObjectContainer::const_iterator oi = leaf->mGeometry.begin();
        for (; oi != leaf->mGeometry.end(); oi++) 
        {
                TriangleIntersectable *object = (TriangleIntersectable *)*oi;
                Triangle3 *t = &(object->GetItem());

                Vector3 normal = t->GetNormal();
                glNormal3f(normal.x, normal.y, normal.z);

                glVertex3f(t->mVertices[0].x, t->mVertices[0].y, t->mVertices[0].z);
                glVertex3f(t->mVertices[1].x, t->mVertices[1].y, t->mVertices[1].z);
                glVertex3f(t->mVertices[2].x, t->mVertices[2].y, t->mVertices[2].z);
        }

        glEnd();
        
        glPopMatrix();

        if (0)
        {
                // render the box of the object
                AxisAlignedBox3 box = leaf->GetBox();
                RenderBox(box);
        }
}



void GlRenderer::_RenderSceneTriangles()
{
        glBegin(GL_TRIANGLES);

        ObjectContainer::const_iterator oi = mObjects.begin();
        for (; oi != mObjects.end(); oi++) {

          if ((*oi)->Type() == Intersectable::TRIANGLE_INTERSECTABLE) {
                        TriangleIntersectable *object = (TriangleIntersectable *)*oi;
                        Triangle3 *t = &(object->GetItem());

                        Vector3 normal = t->GetNormal();
                        glNormal3f(normal.x, normal.y, normal.z);
                        glVertex3f(t->mVertices[0].x, t->mVertices[0].y, t->mVertices[0].z);
                        glVertex3f(t->mVertices[1].x, t->mVertices[1].y, t->mVertices[1].z);
                        glVertex3f(t->mVertices[2].x, t->mVertices[2].y, t->mVertices[2].z);
          }
        }

        glEnd();
}


bool GlRenderer::RenderScene()
{
        ++ mCurrentFrame;

        //Intersectable::NewMail();

        Preprocessor *p = mViewCellsManager->GetPreprocessor();

        // handle dynamic objects
        DynamicObjectsContainer::const_iterator dit, dit_end = p->mDynamicObjects.end();

        for (dit = p->mDynamicObjects.begin(); dit != dit_end; ++ dit)
                _RenderDynamicObject(*dit);

        _RenderSceneTrianglesWithDrawArrays();

        return true;
}



Preprocessor *GlRenderer::GetPreprocessor()
{
        return mViewCellsManager->GetPreprocessor();
}


/****************************************************************/
/*               GlRendererBuffer implementation                */
/****************************************************************/



GlRendererBuffer::GlRendererBuffer(SceneGraph *sceneGraph,
                                                                   ViewCellsManager *viewcells,
                                                                   KdTree *tree):
GlRenderer(sceneGraph, viewcells, tree)  
{ 
        mPixelBuffer = NULL; 
        // implement width and height in subclasses
}


void
GlRendererBuffer::EvalQueryWithItemBuffer()
{
        // read back the texture
        glReadPixels(0, 0,
                GetWidth(), GetHeight(),
                GL_RGBA,
                GL_UNSIGNED_BYTE,
                mPixelBuffer);


        unsigned int *p = mPixelBuffer;

        for (int y = 0; y < GetHeight(); y++)
        {
                for (int x = 0; x < GetWidth(); x++, p++) 
                {
                        unsigned int id = (*p) & 0xFFFFFF;

                        if (id != 0xFFFFFF)
                        {
                                ++ mObjects[id]->mCounter;
                        }
                }
        }
}


void
GlRendererBuffer::EvalQueryWithOcclusionQueries(
                                                                           //RenderCostSample &sample
                                                                           )
{
        glDepthFunc(GL_LEQUAL);
                
        glColorMask(GL_FALSE, GL_FALSE, GL_FALSE, GL_FALSE);
        glDepthMask(GL_FALSE);


        // simulate detectemptyviewspace using backface culling
        if (mDetectEmptyViewSpace) 
        {
                glEnable(GL_CULL_FACE);
                //cout << "culling" << endl;
        }
        else
        {
                //cout << "not culling" << endl;
                glDisable(GL_CULL_FACE);
        }

        
        //const int numQ = 1;
        const int numQ = (int)mOcclusionQueries.size();
        
        //glFinish();
        int q = 0;

        //-- now issue queries for all objects
        for (int j = 0; j < (int)mObjects.size(); j += q) 
        {       
                for (q = 0; ((j + q) < (int)mObjects.size()) && (q < numQ); ++ q) 
                {
                        mOcclusionQueries[q]->BeginQuery();
                        
                        RenderIntersectable(mObjects[j + q]);
                
                        mOcclusionQueries[q]->EndQuery();
                }
                //cout << "q: " << q << endl;
                // collect results of the queries
                for (int t = 0; t < q; ++ t) 
                {
                        unsigned int pixelCount;
                
                        //-- reenable other state

                        pixelCount = mOcclusionQueries[t]->GetQueryResult();

                        //if (pixelCount > 0)
                        //      cout <<"o="<<j+q<<" q="<<mOcclusionQueries[q]->GetQueryId()<<" pc="<<pixelCount<<" ";
                        mObjects[j + t]->mCounter += pixelCount;
                
                }
        }

        //glFinish();
        glColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);
        glDepthMask(GL_TRUE);
        
        glEnable(GL_CULL_FACE);
}


void
GlRenderer::RandomViewPoint()
{ 
  // do not use this function since it could return different viewpoints for
  // different executions of the algorithm

  //  mViewCellsManager->GetViewPoint(mViewPoint);

  while (1) {
        Vector3 pVector = Vector3(halton.GetNumber(1),
                                                          halton.GetNumber(2),
                                                          halton.GetNumber(3));
        
        mViewPoint =  mViewCellsManager->GetViewSpaceBox().GetPoint(pVector);
        ViewCell *v = mViewCellsManager->GetViewCell(mViewPoint);
        if (v && v->GetValid())
          break;
        // generate a new vector
        halton.GenerateNext();
  }
  
  Vector3 dVector = Vector3(2*M_PI*halton.GetNumber(4),
                                                        M_PI*halton.GetNumber(5),
                                                        0.0f);
  
  mViewDirection = Normalize(Vector3(sin(dVector.x),
                                                                         //     cos(dVector.y),
                                                                         0.0f,
                                                                         cos(dVector.x)));
  halton.GenerateNext();
}


void
GlRenderer::RenderBox(const AxisAlignedBox3 &box)
{

  glBegin(GL_LINE_LOOP);
  glVertex3d(box.Min().x, box.Max().y, box.Min().z );
  glVertex3d(box.Max().x, box.Max().y, box.Min().z );
  glVertex3d(box.Max().x, box.Min().y, box.Min().z );
  glVertex3d(box.Min().x, box.Min().y, box.Min().z );
  glEnd();

  glBegin(GL_LINE_LOOP);
  glVertex3d(box.Min().x, box.Min().y, box.Max().z );
  glVertex3d(box.Max().x, box.Min().y, box.Max().z );
  glVertex3d(box.Max().x, box.Max().y, box.Max().z );
  glVertex3d(box.Min().x, box.Max().y, box.Max().z );
  glEnd();

  glBegin(GL_LINE_LOOP);
  glVertex3d(box.Max().x, box.Min().y, box.Min().z );
  glVertex3d(box.Max().x, box.Min().y, box.Max().z );
  glVertex3d(box.Max().x, box.Max().y, box.Max().z );
  glVertex3d(box.Max().x, box.Max().y, box.Min().z );
  glEnd();

  glBegin(GL_LINE_LOOP);
  glVertex3d(box.Min().x, box.Min().y, box.Min().z );
  glVertex3d(box.Min().x, box.Min().y, box.Max().z );
  glVertex3d(box.Min().x, box.Max().y, box.Max().z );
  glVertex3d(box.Min().x, box.Max().y, box.Min().z );
  glEnd();

  glBegin(GL_LINE_LOOP);
  glVertex3d(box.Min().x, box.Min().y, box.Min().z );
  glVertex3d(box.Max().x, box.Min().y, box.Min().z );
  glVertex3d(box.Max().x, box.Min().y, box.Max().z );
  glVertex3d(box.Min().x, box.Min().y, box.Max().z );
  glEnd();

  glBegin(GL_LINE_LOOP);
  glVertex3d(box.Min().x, box.Max().y, box.Min().z );
  glVertex3d(box.Max().x, box.Max().y, box.Min().z );
  glVertex3d(box.Max().x, box.Max().y, box.Max().z );
  glVertex3d(box.Min().x, box.Max().y, box.Max().z );

  glEnd();

}

void
GlRenderer::RenderBvhNode(BvhNode *node)
{
  if (node->IsLeaf()) {
        BvhLeaf *leaf = (BvhLeaf *) node;

#if 0
        if (leaf->mGlList == 0) {
          leaf->mGlList = glGenLists(1);
          if (leaf->mGlList != 0)
                glNewList(leaf->mGlList, GL_COMPILE);
          
          for (int i=0; i < leaf->mObjects.size(); i++)
                RenderIntersectable(leaf->mObjects[i]);
          
          if (leaf->mGlList != 0)
                glEndList();
        }
        
        if (leaf->mGlList != 0)
          glCallList(leaf->mGlList);
#else
        for (int i=0; i < leaf->mObjects.size(); i++)
          RenderIntersectable(leaf->mObjects[i]);
#endif
  } else {
        BvhInterior *in = (BvhInterior *)node;
        RenderBvhNode(in->GetBack());
        RenderBvhNode(in->GetFront());
  }
}

void
GlRenderer::RenderKdNode(KdNode *node)
{
        if (node->IsLeaf()) 
        {
                RenderKdLeaf(static_cast<KdLeaf *>(node));

        } 
        else 
        {
                KdInterior *inter = static_cast<KdInterior *>(node);
                RenderKdNode(inter->mBack);
                RenderKdNode(inter->mFront);
        }
}


void GlRendererBuffer::EvalRenderCostSample(RenderCostSample &sample,
                                                                                        const bool useOcclusionQueries,
                                                                                        const int threshold)
{
        // choose a random view point
        mViewCellsManager->GetViewPoint(mViewPoint);
        sample.mPosition = mViewPoint;
        //cout << "viewpoint: " << mViewPoint << endl;

        // take a render cost sample by rendering a cube
        Vector3 directions[6];

        directions[0] = Vector3(1,0,0);
        directions[1] = Vector3(0,1,0);
        directions[2] = Vector3(0,0,1);
        directions[3] = Vector3(-1,0,0);
        directions[4] = Vector3(0,-1,0);
        directions[5] = Vector3(0,0,-1);

        sample.mVisibleObjects = 0;

        // reset object counters
        ObjectContainer::const_iterator it, it_end = mObjects.end();

        for (it = mObjects.begin(); it != it_end; ++ it) 
                (*it)->mCounter = 0;

        ++ mFrame;

        //glCullFace(GL_FRONT);
        glCullFace(GL_BACK);
        glDisable(GL_CULL_FACE);


        // query all 6 directions for a full point sample
        for (int i = 0; i < 6; ++ i) 
        {
                mViewDirection = directions[i];
                SetupCamera();

                glClearColor(1.0f, 1.0f, 1.0f, 1.0f);
                glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
                //glColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);      glDepthMask(GL_TRUE);
                glDepthFunc(GL_LESS);

                mUseFalseColors = true;

                // the actual scene rendering fills the depth (for occlusion queries)
                // and the frame buffer (for item buffer)
                RenderScene();


                if (0) 
                {
                        char filename[256];
                        sprintf_s(filename, "snap/frame-%04d-%d.png", mFrame, i);
                        //                QImage im = toImage();
                        //                im.save(filename, "PNG");
                }

                // evaluate the sample
                if (useOcclusionQueries) 
                        EvalQueryWithOcclusionQueries();
                else 
                        EvalQueryWithItemBuffer();
        }  

        // now evaluate the statistics over that sample
        // currently only the number of visible objects is taken into account
        sample.Reset();

        for (it = mObjects.begin(); it != it_end; ++ it) 
        {
                Intersectable *obj = *it;
                if (obj->mCounter >= threshold) 
                {
                        ++ sample.mVisibleObjects;
                        sample.mVisiblePixels += obj->mCounter;
                }
        }

        //cout << "RS=" << sample.mVisibleObjects << " ";
}


GlRendererBuffer::~GlRendererBuffer()
{
#if 0
#ifdef USE_CG
        if (sCgFragmentProgram)
                cgDestroyProgram(sCgFragmentProgram);
        if (sCgContext)
                cgDestroyContext(sCgContext);
#endif
#endif

}


void
GlRendererBuffer::SampleRenderCost(const int numSamples,
                                                                   vector<RenderCostSample> &samples,
                                                                   const bool useOcclusionQueries,
                                                                   const int threshold
                                                                   )
{
        MakeLive();

        if (mPixelBuffer == NULL)
                mPixelBuffer = new unsigned int[GetWidth()*GetHeight()];

        // using 90 degree projection to capture 360 view with 6 samples
        SetupProjection(GetHeight(), GetHeight(), 90.0f);

        //samples.resize(numSamples);
        halton.Reset();

        // the number of queries queried in batch mode
        const int numQ = 500;

        //const int numQ = (int)mObjects.size();
        if (useOcclusionQueries)
        {
                cout << "\ngenerating " << numQ << " queries ... ";
                OcclusionQuery::GenQueries(mOcclusionQueries, numQ);
                cout << "finished" << endl;
        }

        // sampling queries 
        for (int i = 0; i < numSamples; ++ i)
        {
                cout << ".";
                EvalRenderCostSample(samples[i], useOcclusionQueries, threshold);
        }

        DoneLive();
}





void
GlRenderer::ClearErrorBuffer()
{
  for (int i=0; i < mPvsStatFrames; i++) {
        mPvsErrorBuffer[i].mError = 1.0f;
  }
  mPvsStat.maxError = 0.0f;
}


void
GlRendererBuffer::EvalPvsStat()
{
        //MakeLive();
        
        GlRenderer::EvalPvsStat();
        
        //DoneLive();
        // mRenderingFinished.wakeAll();
}


void GlRendererBuffer::EvalPvsStat(const SimpleRayContainer &viewPoints)
{
        //MakeLive();

        GlRenderer::EvalPvsStat(viewPoints);
  
        //DoneLive();
}


void GlRendererBuffer::SampleBeamContributions(Intersectable *sourceObject,
                                                                                           Beam &beam,
                                                                                           const int desiredSamples,
                                                                                           BeamSampleStatistics &stat)
{
        // TODO: should be moved out of here (not to be done every time)
        // only back faces are interesting for the depth pass
        glShadeModel(GL_FLAT);
        glDisable(GL_LIGHTING);

        // needed to kill the fragments for the front buffer
        glEnable(GL_ALPHA_TEST);
        glAlphaFunc(GL_GREATER, 0);

        // assumes that the beam is constructed and contains kd-tree nodes
        // and viewcells which it intersects
  
  
        // Get the number of viewpoints to be sampled
        // Now it is a sqrt but in general a wiser decision could be made.
        // The less viewpoints the better for rendering performance, since less passes
        // over the beam is needed.
        // The viewpoints could actually be generated outside of the bounding box which
        // would distribute the 'efective viewpoints' of the object surface and thus
        // with a few viewpoints better sample the viewpoint space....

        //TODO: comment in
        //int viewPointSamples = sqrt((float)desiredSamples);
        int viewPointSamples = max(desiredSamples / (GetWidth() * GetHeight()), 1);
        
        // the number of direction samples per pass is given by the number of viewpoints
        int directionalSamples = desiredSamples / viewPointSamples;
        
        Debug << "directional samples: " << directionalSamples << endl;
        for (int i = 0; i < viewPointSamples; ++ i) 
        {
                Vector3 viewPoint = beam.mBox.GetRandomPoint();
                
                // perhaps the viewpoint should be shifted back a little bit so that it always lies
                // inside the source object
                // 'ideally' the viewpoints would be distributed on the soureObject surface, but this
        // would require more complicated sampling (perhaps hierarchical rejection sampling of
                // the object surface is an option here - only the mesh faces which are inside the box
                // are considered as candidates) 
                
                SampleViewpointContributions(sourceObject,
                                                                         viewPoint,
                                                                         beam,
                                                                         directionalSamples,
                                                                         stat);
        }


        // note:
        // this routine would be called only if the number of desired samples is sufficiently
        // large - for other rss tree cells the cpu based sampling is perhaps more efficient
        // distributing the work between cpu and gpu would also allow us to place more sophisticated
        // sample distributions (silhouette ones) using the cpu and the jittered once on the GPU
        // in order that thios scheme is working well the gpu render buffer should run in a separate
        // thread than the cpu sampler, which would not be such a big problem....

        // disable alpha test again
        glDisable(GL_ALPHA_TEST);
}



void GlRendererBuffer::SampleViewpointContributions(Intersectable *sourceObject,
                                                                                                        const Vector3 viewPoint,
                                                                                                        Beam &beam,
                                                                                                        const int samples,
                                                    BeamSampleStatistics &stat)
{
    // 1. setup the view port to match the desired samples
        glViewport(0, 0, samples, samples);

        // 2. setup the projection matrix and view matrix to match the viewpoint + beam.mDirBox
        SetupProjectionForViewPoint(viewPoint, beam, sourceObject);


        // 3. reset z-buffer to 0 and render the source object for the beam
        //    with glCullFace(Enabled) and glFrontFace(GL_CW)
        //    save result to the front depth map
        //    the front depth map holds ray origins


        // front depth buffer must be initialised to 0
        float clearDepth;
        
        glGetFloatv(GL_DEPTH_CLEAR_VALUE, &clearDepth);
        glClearDepth(0.0f);
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);


        // glFrontFace(GL_CCW);
        glEnable(GL_CULL_FACE);
        glCullFace(GL_FRONT);
        glColorMask(0, 0, 0, 0);
        

        // stencil is increased where the source object is located
        glEnable(GL_STENCIL_TEST);      
        glStencilFunc(GL_ALWAYS, 0x1, 0x1);
        glStencilOp(GL_REPLACE, GL_REPLACE, GL_REPLACE);


#if 0
        static int glSourceObjList = -1;         
        if (glSourceObjList != -1) 
        {
                glSourceObjList = glGenLists(1);
                glNewList(glSourceObjList, GL_COMPILE);

                RenderIntersectable(sourceObject);
        
                glEndList();
        }
        glCallList(glSourceObjList);

#else
        RenderIntersectable(sourceObject);

#endif  

         // copy contents of the front depth buffer into depth texture
        glBindTexture(GL_TEXTURE_2D, frontDepthMap);    
        glCopyTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, 0, 0, depthMapSize, depthMapSize);

        // reset clear function
        glClearDepth(clearDepth);
        
        
        // 4. set up the termination depth buffer (= standard depth buffer)
        //    only rays which have non-zero entry in the origin buffer are valid since
        //    they realy start on the object surface (this is tagged by setting a
        //    stencil buffer bit at step 3).
        
        glStencilFunc(GL_EQUAL, 0x1, 0x1);
        glStencilOp(GL_KEEP, GL_KEEP, GL_KEEP);

        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
        glDepthMask(1);

        glEnable(GL_DEPTH_TEST);
                
        glEnable(GL_CULL_FACE);
        glCullFace(GL_BACK);

        // setup front depth buffer
        glEnable(GL_TEXTURE_2D);
        
#if 0
#ifdef USE_CG
        // bind pixel shader implementing the front depth buffer functionality
        cgGLBindProgram(sCgFragmentProgram);
        cgGLEnableProfile(sCgFragmentProfile);
#endif
#endif
        // 5. render all objects inside the beam 
        //    we can use id based false color to read them back for gaining the pvs

        glColorMask(1, 1, 1, 1);

        
        // if objects not stored in beam => extract objects
        if (beam.mFlags & !Beam::STORE_OBJECTS)
        {
                vector<KdNode *>::const_iterator it, it_end = beam.mKdNodes.end();

                Intersectable::NewMail();
                for (it = beam.mKdNodes.begin(); it != it_end; ++ it)
                {
                        mKdTree->CollectObjects(*it, beam.mObjects);
                }
        }


        //    (objects can be compiled to a gl list now so that subsequent rendering for
        //    this beam is fast - the same hold for step 3)
        //    Afterwards we have two depth buffers defining the ray origin and termination
        

#if 0
        static int glObjList = -1; 
        if (glObjList != -1) 
        {
                glObjList = glGenLists(1);
                glNewList(glObjList, GL_COMPILE);
        
                ObjectContainer::const_iterator it, it_end = beam.mObjects.end();
                for (it = beam.mObjects.begin(); it != it_end; ++ it)
                {
                        // render all objects except the source object
                        if (*it != sourceObject)
                                RenderIntersectable(*it);
                }
                
                glEndList();
        }

        glCallList(glObjList);
#else
        ObjectContainer::const_iterator it, it_end = beam.mObjects.end();
        for (it = beam.mObjects.begin(); it != it_end; ++ it)
        {       
                // render all objects except the source object
                if (*it != sourceObject)
                        RenderIntersectable(*it);
        }
#endif
        
        // 6. Use occlusion queries for all viewcell meshes associated with the beam ->
        //     a fragment passes if the corresponding stencil fragment is set and its depth is
        //     between origin and termination buffer

        // create new queries if necessary
        OcclusionQuery::GenQueries(mOcclusionQueries, (int)beam.mViewCells.size());

        // check whether any backfacing polygon would pass the depth test?
        // matt: should check both back /front facing because of dual depth buffer
        // and danger of cutting the near plane with front facing polys.
        
        glColorMask(GL_FALSE, GL_FALSE, GL_FALSE, GL_FALSE);
        glDepthMask(GL_FALSE);
        glDisable(GL_CULL_FACE);

  
        ViewCellContainer::const_iterator vit, vit_end = beam.mViewCells.end();

        int queryIdx = 0;

        for (vit = beam.mViewCells.begin(); vit != vit_end; ++ vit)
        {
                mOcclusionQueries[queryIdx ++]->BeginQuery();
                RenderIntersectable(*vit);
                mOcclusionQueries[queryIdx]->EndQuery();

                ++ queryIdx;
        }

        // at this point, if possible, go and do some other computation

        // 7. The number of visible pixels is the number of sample rays which see the source
        //    object from the corresponding viewcell -> remember these values for later update
        //   of the viewcell pvs - or update immediately?

        queryIdx = 0;

        for (vit = beam.mViewCells.begin(); vit != vit_end; ++ vit)
        {
                // fetch queries
                unsigned int pixelCount = mOcclusionQueries[queryIdx ++]->GetQueryResult();

                if (pixelCount)
                        Debug << "view cell " << (*vit)->GetId() << " visible pixels: " << pixelCount << endl;
        }
        

        // 8. Copmpute rendering statistics
        // In general it is not neccessary to remember to extract all the rays cast. I hope it
        // would be sufficient to gain only the intergral statistics about the new contributions
        // and so the rss tree would actually store no new rays (only the initial ones)
        // the subdivision of the tree would only be driven by the statistics (the glrender could
        // evaluate the contribution entropy for example)
        // However might be an option to extract/store only those the rays which made a contribution
        // (new viewcell has been discovered) or relative contribution greater than a threshold ... 

        ObjectContainer pvsObj;
        stat.pvsSize = ComputePvs(beam.mObjects, pvsObj);
        
        // to gain ray source and termination
        // copy contents of ray termination buffer into depth texture
        // and compare with ray source buffer
#if 0
        VssRayContainer rays;

        glBindTexture(GL_TEXTURE_2D, backDepthMap);     
        glCopyTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, 0, 0, depthMapSize, depthMapSize);

        ComputeRays(Intersectable *sourceObj, rays);

#endif

        ////////
        //-- cleanup

        // reset gl state
        glColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);
        glDepthMask(GL_TRUE);
        glEnable(GL_CULL_FACE);
        glDisable(GL_STENCIL_TEST);

#if 0
#ifdef USE_CG
        cgGLDisableProfile(sCgFragmentProfile);
#endif
#endif

        glDisable(GL_TEXTURE_2D);

        // remove objects from beam
        if (beam.mFlags & !Beam::STORE_OBJECTS)
                beam.mObjects.clear();
}


void GlRendererBuffer::SetupProjectionForViewPoint(const Vector3 &viewPoint, 
                                                                                                   const Beam &beam, 
                                                                                                   Intersectable *sourceObject)
{
        float left, right, bottom, top, znear, zfar;

        beam.ComputePerspectiveFrustum(left, right, bottom, top, znear, zfar,
                                                                   mSceneGraph->GetBox());

        //Debug << left << " " << right << " " << bottom << " " << top << " " << znear << " " << zfar << endl;
        glMatrixMode(GL_PROJECTION);
        glLoadIdentity();
        glFrustum(left, right, bottom, top, znear, zfar);
        //glFrustum(-1, 1, -1, 1, 1, 20000);

    const Vector3 center = viewPoint + beam.GetMainDirection() * (zfar - znear) * 0.3f;
        const Vector3 up = 
                Normalize(CrossProd(beam.mPlanes[0].mNormal, beam.mPlanes[4].mNormal));

#ifdef GTP_DEBUG
        Debug << "view point: " << viewPoint << endl;
        Debug << "eye: " << center << endl;
        Debug << "up: " << up << endl;
#endif

        glMatrixMode(GL_MODELVIEW);
        glLoadIdentity();
        gluLookAt(viewPoint.x, viewPoint.y, viewPoint.z, 
                          center.x, center.y, center.z,                   
                          up.x, up.y, up.z);
}               

  
void GlRendererBuffer::InitGL()
{
        //MakeCurrent(); 
        GlRenderer::InitGL();

#if 0
        // initialise dual depth buffer textures
        glGenTextures(1, &frontDepthMap);
        glBindTexture(GL_TEXTURE_2D, frontDepthMap);

        glTexImage2D(GL_TEXTURE_2D, 0, GL_DEPTH_COMPONENT, depthMapSize, 
                depthMapSize, 0, GL_DEPTH_COMPONENT, GL_UNSIGNED_BYTE, NULL);

        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP);

        glGenTextures(1, &backDepthMap);
        glBindTexture(GL_TEXTURE_2D, backDepthMap);

        glTexImage2D(GL_TEXTURE_2D, 0, GL_DEPTH_COMPONENT, depthMapSize, 
                                 depthMapSize, 0, GL_DEPTH_COMPONENT, GL_UNSIGNED_BYTE, NULL);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP);


#ifdef USE_CG

        // cg initialization
        cgSetErrorCallback(handleCgError);
        sCgContext = cgCreateContext();

        if (cgGLIsProfileSupported(CG_PROFILE_ARBFP1))
                sCgFragmentProfile = CG_PROFILE_ARBFP1;
        else 
        {
                // try FP30
                if (cgGLIsProfileSupported(CG_PROFILE_FP30))
                        sCgFragmentProfile = CG_PROFILE_FP30;
                else 
                {
                        Debug << "Neither arbfp1 or fp30 fragment profiles supported on this system" << endl;
                        exit(1);
                }
        }

        sCgFragmentProgram = cgCreateProgramFromFile(sCgContext,
                                                         CG_SOURCE, "../src/dual_depth.cg",
                                                                                                 sCgFragmentProfile,
                                                                                                 NULL, 
                                                                                                 NULL);

        if (!cgIsProgramCompiled(sCgFragmentProgram))
                cgCompileProgram(sCgFragmentProgram);

        cgGLLoadProgram(sCgFragmentProgram);
        cgGLBindProgram(sCgFragmentProgram);

        Debug << "---- PROGRAM BEGIN ----\n" <<
                cgGetProgramString(sCgFragmentProgram, CG_COMPILED_PROGRAM) << "---- PROGRAM END ----\n";

#endif
#endif
        //DoneCurrent();
}


void GlRendererBuffer::ComputeRays(Intersectable *sourceObj, VssRayContainer &rays)
{
        for (int i = 0; i < depthMapSize * depthMapSize; ++ i)
        {
                // TODO (use glGetTexImage())
        }
}


bool GlRendererBuffer::ValidViewPoint()
{       
        MakeLive();

        SetupProjection(GetWidth(), GetHeight());

        bool result = GlRenderer::ValidViewPoint();
        
        DoneLive();
        
        return result;
}


void
GlRenderer::EvalPvsStat()
{
        mPvsStat.Reset();
        halton.Reset();

        SetupProjection(GetWidth(), GetHeight());

        cout << "Random Pvs STATS, mPvsStatFrames=" << mPvsStatFrames << endl;

        for (int i=0; i < mPvsStatFrames; i++) {
                float err;
                // set frame id for saving the error buffer
                mFrame = i;

                //      cerr<<"RV"<<endl;
                RandomViewPoint();
                //      cerr<<"RV2"<<endl;

                if (mPvsErrorBuffer[i].mError == 1.0f) {
                        // check if the view point is valid
                        if (!ValidViewPoint()) {
                                mPvsErrorBuffer[i].mError = -1.0f;
                        }

                        // manualy corrected view point
                        if (mFrame == 5105)
                                mPvsErrorBuffer[i].mError = -1.0f;
                }


                if (mPvsErrorBuffer[i].mError > 0.0f) 
                {
                        int pvsSize;

                        mPvsErrorBuffer[i].mError = GetPixelError(pvsSize, 0);
                        mPvsErrorBuffer[i].mPvsSize = pvsSize;

                        //cout<<"("<<i<<" ["<<mViewPoint<<"]["<<mViewDirection<<"] "<<mPvsErrorBuffer[i].mError<<")";
                }

                err = mPvsErrorBuffer[i].mError;

                if (err >= 0.0f) {
                        if (err > mPvsStat.maxError)
                                mPvsStat.maxError = err;
                        mPvsStat.sumError += err;
                        mPvsStat.sumPvsSize += mPvsErrorBuffer[i].mPvsSize;

                        if (err == 0.0f)
                                mPvsStat.errorFreeFrames++;
                        mPvsStat.frames++;
                }
        }

        glFinish();

        static bool first = true;

        if (first) {

                bool exportRandomViewCells;
                Environment::GetSingleton()->GetBoolValue("ViewCells.exportRandomViewCells",
                        exportRandomViewCells);

                if (0 && exportRandomViewCells)
                {
                        char buff[512];
                        Environment::GetSingleton()->GetStringValue("Scene.filename", buff);
                        string filename(buff);

                        string viewCellPointsFile;

                        if (strstr(filename.c_str(), ".obj"))
                                viewCellPointsFile = ReplaceSuffix(filename, ".obj", ".vc");
                        else if (strstr(filename.c_str(), ".dat"))
                                viewCellPointsFile = ReplaceSuffix(filename, ".dat", ".vc");
                        else if (strstr(filename.c_str(), ".x3d"))
                                viewCellPointsFile = ReplaceSuffix(filename, ".x3d", ".vc");


                        cout << "exporting random view cells" << endl;
                        preprocessor->mViewCellsManager->ExportRandomViewCells(viewCellPointsFile);
                        cout << "finished" << endl;
                }
                first = false;
        }

        cout<<endl<<flush;
}


void GlRenderer::EvalPvsStat(const SimpleRayContainer &viewPoints)
{
        mPvsStat.Reset();
        ++ mPvsStat.currentPass;

        SetupProjection(GetWidth(), GetHeight());

        cout << "mPvsStatFrames=" << viewPoints.size() << endl;

        SimpleRayContainer::const_iterator sit, sit_end = viewPoints.end();

        int i = 0;
        // $matt tmp: somehow this is not properly initialised
        //ClearErrorBuffer();
        
        for (sit = viewPoints.begin(); sit != sit_end; ++ sit, ++ i) 
        {
                SimpleRay sray = *sit;
                int pvsSize = -1;

                // set frame id for saving the error buffer
                mFrame = i;
                mViewPoint = sray.mOrigin;
                mViewDirection = sray.mDirection;

                //cout << "handling vp " << mFrame << " " << mViewPoint << " " << mViewDirection << endl;
                // skip all frames which have already 0 pixel error
                // $$ Reverted back by JB for efficiency
                if (1)//mPvsErrorBuffer[i].mError > 0.0f) 
                {
                        // compute the pixel error
                        mPvsErrorBuffer[i].mError = GetPixelError(pvsSize, mPvsStat.currentPass);
                        mPvsErrorBuffer[i].mPvsSize = pvsSize;

                        if ((mPvsErrorBuffer[i].mError * GetWidth() * GetHeight() > 0) && (pvsSize > 0)) 
                        {
                                cout << "error in frame " << i << "," << mViewPoint << "," << mViewDirection << " " 
                                         << mPvsErrorBuffer[i].mError * GetWidth() * GetHeight() << endl;
                        }
                }

                const float err = mPvsErrorBuffer[i].mError;

                // hack:
                // do not account for the case that no PVS is rendered - hack for 08 rebuttal GVS evaluation
                // drop the first frame (for some reason, the first frame yields wrong pixel error)
                
                if (pvsSize != 0)
                {
                        // hack: test if error is suspiciously large
                        if ((err >=  -1e-6f) && (err < (1.0f - 1e-6f)))
                        {
                                if (err > mPvsStat.maxError)
                                {
                                        mPvsStat.maxError = err;
                                        cout << "new max error: " << mPvsStat.maxError * GetWidth() * GetHeight()  << endl;
                                }

                                mPvsStat.sumError += err;
                                mPvsStat.sumPvsSize += mPvsErrorBuffer[i].mPvsSize;

                                if (err == 0.0f)
                                        ++ mPvsStat.errorFreeFrames;

                                // $$ JB
                                // moved it back here not to count frames with negative err (backfacing triangle)
                                ++ mPvsStat.frames;

                                if ((mPvsStat.frames % 100) == 0)
                                        cout << "processed " << mPvsStat.frames << " valid view points " << endl;
                        }
                        else
                        {
                                cerr << "warning: strange error (" << err << "), pvs size " << pvsSize << endl;
                        }
                }
        }

        glFinish();


        cout << endl << flush;
}



bool
GlRenderer::ValidViewPoint()
{
        //cout<<"VV4 ";
        if (!mDetectEmptyViewSpace)
                return true;
        //cout << "vp: " << mViewPoint << " dir: " << mViewDirection << endl;

        OcclusionQuery *query = mOcclusionQueries[0];

        // now check whether any backfacing polygon would pass the depth test
        SetupCamera();
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
        glEnable( GL_CULL_FACE );
        glCullFace(GL_BACK);

        //cout<<"VV1 ";
        RenderScene();

        glColorMask(GL_FALSE, GL_FALSE, GL_FALSE, GL_FALSE);
        glDepthMask(GL_FALSE);
        glDisable( GL_CULL_FACE );

        query->BeginQuery();

        //  cout<<"VV2 ";
        RenderScene();
        //  cout<<"VV3 ";

        query->EndQuery();

        // at this point, if possible, go and do some other computation
        glColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);
        glDepthMask(GL_TRUE);
        glEnable(GL_CULL_FACE);

        //      int wait = 0;
        //      while (!query->ResultAvailable()) {
        //        wait++;
        //      }

        // reenable other state
        unsigned int pixelCount = query->GetQueryResult();
        //  cout<<"VV4 ";


        // backfacing polygon found -> not a valid viewspace sample
        if (pixelCount > 0)
                return false; 
        
        return true;
}


float GlRenderer::GetPixelError(int &pvsSize, int pass)
{
        return -1.0f;
}


void GlRenderer::RenderViewPoint()
{
        //mWireFrame = true;
        glPushMatrix();
        glTranslatef(mViewPoint.x, mViewPoint.y, mViewPoint.z);
        glScalef(5.0f, 5.0f, 5.0f);
        glPushAttrib(GL_CURRENT_BIT);
        glColor3f(1.0f, 0.0f, 0.0f);
        gluSphere((::GLUquadric *)mSphere,
                1e-3*Magnitude(mViewCellsManager->GetViewSpaceBox().Size()), 6, 6);
        glPopAttrib();
        glPopMatrix();
        //mWireFrame = false;
}


void GlRenderer::EnableDrawArrays()
{
  glEnableClientState(GL_VERTEX_ARRAY);
  glEnableClientState(GL_NORMAL_ARRAY);
}


void GlRenderer::DisableDrawArrays()
{
        glDisableClientState(GL_VERTEX_ARRAY);
        glDisableClientState(GL_NORMAL_ARRAY);
}


#if 0

void GlRenderer::RenderKdLeaf(KdLeaf *leaf)
{
        int bufferSize = 0;

        // count #new triangles
        for (size_t i = 0; i < leaf->mObjects.size(); ++ i)
        {
                TriangleIntersectable *obj = static_cast<TriangleIntersectable *>(leaf->mObjects[i]);

                // check if already rendered
                if (!obj->Mailed2())
                        bufferSize += 3;
                //else cout << obj->mMailbox << " " << obj->sMailId << " ";
        }

        Vector3 *vertices = new Vector3[bufferSize];
        Vector3 *normals = new Vector3[bufferSize];

        int j = 0;

        for (size_t i = 0; i < leaf->mObjects.size(); ++ i)
        {
                TriangleIntersectable *obj = static_cast<TriangleIntersectable *>(leaf->mObjects[i]);

                // check if already rendered
                if (obj->Mailed2())
                        continue;

                obj->Mail2();

                Triangle3 tri = obj->GetItem();

                vertices[j * 3 + 0] = tri.mVertices[0];
                vertices[j * 3 + 1] = tri.mVertices[1];
                vertices[j * 3 + 2] = tri.mVertices[2];

                Vector3 n = tri.GetNormal();

                normals[j * 3 + 0] = n;
                normals[j * 3 + 1] = n;
                normals[j * 3 + 2] = n;

                ++ j;
        }

        glVertexPointer(3, GL_FLOAT, 0, vertices);
        glNormalPointer(GL_FLOAT, 0, normals);

        glDrawArrays(GL_TRIANGLES, 0, bufferSize);

        DEL_PTR(vertices);
        DEL_PTR(normals);
}

#else

void GlRenderer::RenderKdLeaf(KdLeaf *leaf)
{
        if (!leaf->mIndexBufferSize)
                return;

        size_t offset = mObjects.size() * 3;
        char *arrayPtr = mUseVbos ? NULL : (char *)mData;
        
        glVertexPointer(3, GL_FLOAT, 0, (char *)arrayPtr);
        glNormalPointer(GL_FLOAT, 0, (char *)arrayPtr + offset * sizeof(Vector3));
        
        glDrawElements(GL_TRIANGLES, leaf->mIndexBufferSize, GL_UNSIGNED_INT, 
                           mIndices + leaf->mIndexBufferStart);
}

#endif


void GlRenderer::PreparePvs(const ObjectPvs &pvs)
{
        int indexBufferSize = 0;
        mRenderedNodes = 0;

        KdNode::NewMail2();
                
        ObjectPvsIterator it = pvs.GetIterator();

        while (it.HasMoreEntries()) 
        {
                Intersectable *obj = it.Next();
                switch (obj->Type())
                {
                case Intersectable::KD_INTERSECTABLE:
                        {
                                KdNode *node = static_cast<KdIntersectable *>(obj)->GetItem();
                                _UpdatePvsIndices(node, indexBufferSize);
                        }
                        break;
                        
                }
        }

        mIndexBufferSize = indexBufferSize;
}


void GlRenderer::_UpdatePvsIndices(KdNode *node, int &indexBufferSize)
{
        if (node->Mailed2())
                return;

        node->Mail2();

        // if (mObjects.size() * 3 < indexBufferSize) cerr << "problem: " << mObjects.size() * 3 << " < " << indexBufferSize << endl;
        if (!node->IsLeaf()) 
        {
                KdInterior *kdInterior = static_cast<KdInterior *>(node);

                _UpdatePvsIndices(kdInterior->mBack, indexBufferSize);
                _UpdatePvsIndices(kdInterior->mFront, indexBufferSize);
        } 
        else 
        {
                KdLeaf *leaf = static_cast<KdLeaf *>(node);

                leaf->mIndexBufferStart = indexBufferSize;

                for (size_t i = 0; i < leaf->mObjects.size(); ++ i)
                {
                        TriangleIntersectable *obj = 
                                static_cast<TriangleIntersectable *>(leaf->mObjects[i]);

                        if (obj->mRenderedFrame != mCurrentFrame)
                        {
                                obj->mRenderedFrame = mCurrentFrame;
                                
                                const int id = obj->GetId() * 3;

                                mIndices[indexBufferSize + 0] = id + 0;
                                mIndices[indexBufferSize + 1] = id + 1;
                                mIndices[indexBufferSize + 2] = id + 2;

                                indexBufferSize += 3;
                        }
                }

                ++ mRenderedNodes;

                leaf->mIndexBufferSize = indexBufferSize - leaf->mIndexBufferStart;
        }
}


void GlRenderer::CreateVertexArrays(SceneGraphLeaf *leaf)
{
        size_t offset = leaf->mGeometry.size() * 3;

    mData = new Vector3[offset * 2];
        mIndices = new unsigned int[offset];


        for (size_t i = 0; i < leaf->mGeometry.size(); ++ i)
        {
                TriangleIntersectable *obj = static_cast<TriangleIntersectable *>(leaf->mGeometry[i]);

                Triangle3 tri = obj->GetItem();
                const Vector3 n = tri.GetNormal();

                mData[i * 3 + 0] = tri.mVertices[0];
                mData[i * 3 + 1] = tri.mVertices[1];
                mData[i * 3 + 2] = tri.mVertices[2];

                mData[offset + i * 3 + 0] = n;
                mData[offset + i * 3 + 1] = n;
                mData[offset + i * 3 + 2] = n;

                mIndices[i * 3 + 0] = 0;
                mIndices[i * 3 + 1] = 0;
                mIndices[i * 3 + 2] = 0;
        }

        cout << "\n******** created vertex arrays **********" << endl;  

        if (mUseVbos)
        {
                EnableDrawArrays();

                glGenBuffersARB(1, &mVboId);
                glBindBufferARB(GL_ARRAY_BUFFER_ARB, mVboId);

                glVertexPointer(3, GL_FLOAT, 0, (char *)NULL);
                glNormalPointer(GL_FLOAT, 0, (char *)NULL + offset * sizeof(Vector3));

                glBufferDataARB(GL_ARRAY_BUFFER_ARB, offset * 2 * sizeof(Vector3), mData, GL_STATIC_DRAW_ARB);
                glBindBufferARB(GL_ARRAY_BUFFER_ARB, 0);

                DisableDrawArrays();

                delete [] mData;
                mData = NULL;

                cout << "\n******** created vertex buffer objects **********" << endl;  
        }
}


void GlRenderer::DeleteVbos()
{
        glDeleteBuffersARB(1, &mVboId);
}


void GlRenderer::_RenderColoredPvs(const ObjectPvs &pvs)
{
        // note: could be done more efficiently using color buffers
        ObjectPvsIterator it = pvs.GetIterator();

        PvsData pvsData;

        while (it.HasMoreEntries())
        {
                Intersectable *obj = it.Next(pvsData);

                RgbColor color;

                //cerr << "sumpdf: " << pvsData.mSumPdf << endl;
                if (1)//mUseRandomColorPerPvsObject)
                {
                        if (obj->Type() == Intersectable::KD_INTERSECTABLE)
                        {
                                KdIntersectable *kdint = static_cast<KdIntersectable *>(obj);

                                if (kdint->mGenericIdx == -1)
                                {
                                        kdint->mGenericIdx = (int)mColors.size();
                                        mColors.push_back(RandomColor(0, 1));
                                }

                                color = mColors[kdint->mGenericIdx];
                        }
                } 
                else
                {
                        color = RainbowColorMapping(log10(pvsData.mSumPdf + 1));
                }

                glColor3f(color.r, color.g, color.b);

                mUseForcedColors = true;
                RenderIntersectable(obj);
                mUseForcedColors = false;
        }
}



}