initInstanced()
{
glGenBuffers(1, &this->grassTBO);
    glBindBuffer(GL_TEXTURE_BUFFER, *geom->getTBO());
    glBufferData(GL_TEXTURE_BUFFER, sizeof(InstanceData)*geom->numGrass, NULL, GL_STATIC_DRAW);

    // generate the grass instance data
    InstanceData* instance = (InstanceData*)glMapBufferRange(GL_TEXTURE_BUFFER, 0, sizeof(InstanceData)*geom->numGrass,
                 GL_MAP_WRITE_BIT | GL_MAP_INVALIDATE_BUFFER_BIT | GL_MAP_UNSYNCHRONIZED_BIT);
    int size = (int)sqrt((float)this->numGrass);
    for (int i=0; i<size; i++) {
    	for (int j=0; j<size; j++) {
        instance[i+j*size].position = vec4( (i-size/2)*4.0f+sf::Randomizer::Random(-0.05f, 0.05f), -5.5f, (j-size/2)*4.0f+sf::Randomizer::Random(-0.05f, 0.05f), 0.0f );
    	}
    }
    glUnmapBuffer(GL_TEXTURE_BUFFER);

    // create the vertex array for culling
    glGenVertexArrays(1, *geom->getVertexArray());
    glBindVertexArray(geom->getVertexArray());
    glBindBuffer(GL_ARRAY_BUFFER, geom->getTBO());
    glEnableVertexAttribArray(0);
    glVertexAttribPointer(0, 4, GL_FLOAT, GL_FALSE, sizeof(GLfloat)*4, (void*)0);

}

render()
{
glEnable(GL_RASTERIZER_DISCARD);
    
    
    extensions->glBindBufferBase(GL_TRANSFORM_FEEDBACK_BUFFER, 0, geom->getCulledTbo()->getBufferId());
    geom->getVertexArray()->bind();
    extensions->glBeginTransformFeedback(GL_POINTS);
	 	extensions->glBeginQueryIndexed(GL_PRIMITIVES_GENERATED, 0, *geom->getCulledQuery());
    	extensions->glDrawArrays(GL_POINTS, 0, (GLsizei)geom->getMaxNumInstanced());
    extensions->glEndQueryIndexed(GL_PRIMITIVES_GENERATED, 0);
    extensions->glEndTransformFeedback();
    glDisable(GL_RASTERIZER_DISCARD);
    geom->getVertexArray()->unbind();
    while(true)
    {
    	// Apparently, must actually sleep here to avoid issues w/ NVIDIA Quadro.
    	extensions->glGetQueryObjectiv( geom->getCulledQueryAsValue(), GL_QUERY_RESULT_AVAILABLE, &ready );
    	if (!ready) OpenThreads::Thread::microSleep(1000);
    	else break;
    }	

    numVisible = 0;
    unsigned int sum = 0;
    for(unsigned int i = 0; i < lodCount; i++)
    {
    	extensions->glGetQueryObjectiv(geom->getCulledQueryAsValue(i), GL_QUERY_RESULT, &numVisible);
    	geom->drawInstanced(numVisible)
    }

}