#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),
//mUseVbos(true),
mUseVbos(false),
mCurrentFrame(-1)
{
	mSceneGraph->CollectObjects(mObjects);

#if 0
	viewCellsManager->GetViewPoint(mViewPoint);
	mViewDirection = Vector3(0,0,1);
#else
	
	mViewPoint = Vector3(1213.85, 176.988, -437.364);
	mViewDirection = Vector3(0.433884, 0, -0.900969);
	
	//mViewPoint = Vector3(1099.9,183.0,-387);
	//mViewDirection = Vector3(-0.6,0,-0.8);
#endif
	mFrame = 0;
	mWireFrame = false;
	Environment::GetSingleton()->GetBoolValue("Preprocessor.detectEmptyViewSpace",
		                                      mDetectEmptyViewSpace);

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

	if (mViewCellsManager->GetViewCellPointsList()->size())
		mPvsStatFrames = (int)mViewCellsManager->GetViewCellPointsList()->size();
	else
		Environment::GetSingleton()->GetIntValue("Preprocessor.pvsRenderErrorSamples",
												 mPvsStatFrames);
	
	
	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);

	OcclusionQuery::GenQueries(mOcclusionQueries, 10);

	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, 0.1, 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);

	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, (int)mObjects.size() * 3);
	//DisableDrawArrays();
}


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();
}



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();
#if DYNAMIC_OBJECTS_HACK
	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)
	{
#if USE_TRANSFORMED_MESH_INSTANCE_HACK
        RenderIntersectable(*dit);
#else
		_RenderDynamicObject(*dit);
#endif
	}
#endif
#if 1
	_RenderSceneTrianglesWithDrawArrays();

#else
	static int glList = -1;
	if (mUseGlLists) {
		if (glList == -1) {
			glList = glGenLists(1);
			glNewList(glList, GL_COMPILE);
			_RenderSceneTriangles();
			glEndList();
		}

		glCallList(glList);
	} else
		_RenderSceneTriangles();

#endif
	return true;
}


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;
			}
		}
	}
}



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



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


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();
#if 0
	//-- now issue queries for all objects
	for (int j = 0; j < (int)mObjects.size(); ++ j) 
	{
		mOcclusionQueries[j]->BeginQuery();
		RenderIntersectable(mObjects[j]);
		mOcclusionQueries[j]->EndQuery();

		unsigned int pixelCount;

		pixelCount = mOcclusionQueries[j]->GetQueryResult();
		
		mObjects[j]->mCounter += pixelCount;
	}
#else

	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) 
		{
			//glFinish();
			mOcclusionQueries[q]->BeginQuery();
			
			RenderIntersectable(mObjects[j + q]);
		
			mOcclusionQueries[q]->EndQuery();
			//glFinish();
		}
		//cout << "q: " << q << endl;
		// collect results of the queries
		for (int t = 0; t < q; ++ t) 
		{
			unsigned int pixelCount;
		
			//-- reenable other state
#if 0
			bool available;

			do 
			{
				available = mOcclusionQueries[t]->ResultAvailable();
				
				if (!available) cout << "W";
			} 
			while (!available);
#endif

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

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

		//j += q;
	}
#endif
	//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()) 
	{
#if !EVAL_ERROR
		RenderKdLeaf(static_cast<KdLeaf *>(node));
#else
		KdLeaf *leaf = static_cast<KdLeaf *>(node);
		for (int i=0; i < leaf->mObjects.size(); i++) 
		  {
			RenderIntersectable(leaf->mObjects[i]);
			
		  }
#endif
	} 
	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(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
								   )
{
	MakeCurrent();

	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);
	}

	DoneCurrent();
}





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


void
GlRendererBuffer::EvalPvsStat()
{
	MakeCurrent();
	
	GlRenderer::EvalPvsStat();
	
	DoneCurrent();
  //  mRenderingFinished.wakeAll();
}


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

	GlRenderer::EvalPvsStat(viewPoints);
  
	DoneCurrent();
}


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();

	// 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);

#if 0
#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 glGetTexImage()
	}
}

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

	SetupProjection(GetWidth(), GetHeight());

	bool result = GlRenderer::ValidViewPoint();
	
	DoneCurrent();
	
	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;
	}
	
	
	// atlanta problematic frames: 325 525 691 1543
#if 0
	if (mFrame != 325 &&
		mFrame != 525 &&
		mFrame != 691 &&
		mFrame != 1543)
	  mPvsErrorBuffer[i] = -1;
	else {
	  Debug<<"frame ="<<mFrame<<" vp="<<mViewPoint<<" vd="<<mViewDirection<<endl;
	}
#endif
	

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

	  float error = GetPixelError(pvsSize);

	  mPvsErrorBuffer[i].mError = error;
	  mPvsErrorBuffer[i].mPvsSize = pvsSize;

	  //	  emit UpdatePvsErrorItem(i,
	  //							  mPvsErrorBuffer[i]);
	  cout<<"("<<i<<" ["<<mViewPoint<<"]["<<mViewDirection<<"] "<<mPvsErrorBuffer[i].mError<<")";
	  //	  swapBuffers();
	}
	
	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();
  cout<<endl<<flush;
}


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

  SetupProjection(GetWidth(), GetHeight());
  
  cout << "mPvsStatFrames=" << mPvsStatFrames << endl;
  
  SimpleRayContainer::const_iterator sit, sit_end = viewPoints.end();
  int i = 0;
  
  for (sit = viewPoints.begin(); sit != sit_end; ++ sit, ++ i) 
	{
	  
	  //cout << "view point: " << (*sit) << endl;;
	  SimpleRay sray = *sit;
	  
	  float err;
	  
	  // set frame id for saving the error buffer
	  mFrame = i;
	  mViewPoint = sray.mOrigin;
	  mViewDirection = sray.mDirection;
	  
	  if (mPvsErrorBuffer[i].mError > 0.0f) 
	  {
		  int pvsSize;

		  // compute the pixel error
		  float error = GetPixelError(pvsSize);
		  
		  mPvsErrorBuffer[i].mError = error;
		  mPvsErrorBuffer[i].mPvsSize = pvsSize;

		  cout << "(" << i << "," << 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();
  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 ";


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


float GlRenderer::GetPixelError(int &pvsSize)
{
  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->Mailed())
			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->Mailed())
			continue;

		obj->Mail();

		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;
	
	KdNode::NewMail();
	//Intersectable::NewMail();

	
	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->Mailed())
		return;

	node->Mail();

	// 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;

				mIndices[indexBufferSize + 0] = (obj->GetId() - 1) * 3 + 0;
				mIndices[indexBufferSize + 1] = (obj->GetId() - 1) * 3 + 1;
				mIndices[indexBufferSize + 2] = (obj->GetId() - 1) * 3 + 2;

				indexBufferSize += 3;
			}
		}

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

	//cout << "id: " << indexBufferSize << endl;
}

void GlRenderer::CreateVertexArrays(SceneGraphLeaf *leaf)
{
    mData = new Vector3[leaf->mGeometry.size() * 6];
	mIndices = new unsigned int[leaf->mGeometry.size() * 3];

	size_t offset = leaf->mGeometry.size() * 3;

	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;
	}

	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, leaf->mGeometry.size() * 6 * sizeof(Vector3), mData, GL_STATIC_DRAW_ARB);
		glBindBufferARB(GL_ARRAY_BUFFER_ARB, 0);

		DisableDrawArrays();

		delete [] mData;
	}

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


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

/*
	KdLeafContainer leaves;
	mKdTree->CollectLeaves(leaves);

	KdLeafContainer::const_iterator kit, kit_end = leaves.end();

	for (kit = leaves.begin(); kit != kit_end; ++ kit)
	{
		KdLeaf *leaf = *kit;

		if (leaf->mVboId == -1)
		{
			// delete old vbo
			glDeleteBuffersARB(1, &leaf->mVboId);
			leaf->mVboId = -1;
		}
	}
*/
}



}