source: trunk/VUT/GtpVisibility/src/CoherentHierarchicalCullingManager.cpp @ 74

#include "CoherentHierarchicalCullingManager.h"

namespace GtpVisibility {

//-----------------------------------------------------------------------
void CoherentHierarchicalCullingManager::RenderScene()
{
        QueryQueue queryQueue;
        mNumFrustumCulledNodes = mNumQueryCulledNodes = 0;

        //-- PART 1: process finished occlusion queries
        while (!mHierarchyInterface->GetQueue()->empty() || !queryQueue.empty())
        {
                while (!queryQueue.empty() && 
                           (queryQueue.front().second->ResultAvailable() || mHierarchyInterface->GetQueue()->empty()))
                {
                        HierarchyNode *node = queryQueue.front().first;
                                        
                        // wait until result available
                        unsigned int visiblePixels = queryQueue.front().second->GetQueryResult();
                        
                        queryQueue.pop();

                        if (visiblePixels > mVisibilityThreshold)
                        {
                                mHierarchyInterface->PullUpVisibility(node);
                                mHierarchyInterface->TraverseNode(node);
                        }
                        else
                        {
                                mNumQueryCulledNodes ++;
                        }
                }       

                //-- PART 2: hierarchical traversal
                if (!mHierarchyInterface->GetQueue()->empty())
                {
                        HierarchyNode *node = mHierarchyInterface->GetQueue()->top();
                        mHierarchyInterface->GetQueue()->pop();
                                
                        bool intersects = false;

                        if (!mHierarchyInterface->CheckFrustumVisible(node, intersects))
                        {
                                mNumFrustumCulledNodes ++;
                        }
                        else
                        {
                                // if intersects near plane => skip occlusion query because wrong results possible
                                if (intersects)
                                {
                                        // update octant's visited flag
                                        mHierarchyInterface->SetLastVisited(node, mHierarchyInterface->GetFrameId());

                                        mHierarchyInterface->PullUpVisibility(node);                    
                                        mHierarchyInterface->TraverseNode(node);

                                        continue;
                                }

                                // identify previously visible nodes
                                bool wasVisible = mHierarchyInterface->IsNodeVisible(node) && 
                                        (mHierarchyInterface->LastVisited(node) == mHierarchyInterface->GetFrameId() - 1);
                                
                                // identify nodes that we cannot skip queries for
                                bool mustQuery = !wasVisible || mHierarchyInterface->HasGeometry(node) || mHierarchyInterface->IsLeaf(node);

                                // reset node's visibility classification 
                                mHierarchyInterface->SetNodeVisible(node, false);

                                // update node's visited flag
                                mHierarchyInterface->SetLastVisited(node, mHierarchyInterface->GetFrameId());
                        
                                // skip testing previously visible interior nodes
                                if (mustQuery)
                                {
                                        queryQueue.push(QueryPair(node, mHierarchyInterface->IssueOcclusionQuery(node)));
                                }
                                        
                                // always traverse a node if it was visible
                                if (wasVisible)
                                {
                                        mHierarchyInterface->TraverseNode(node);
                                }
                        }
                }
        }
}

} // namespace GtpVisibility