source: trunk/VUT/GtpVisibility/src/CoherentHierarchicalCullingManager.cpp @ 148

#include "CoherentHierarchicalCullingManager.h"
#include <OgreLogManager.h>

namespace GtpVisibility {

//-----------------------------------------------------------------------
CoherentHierarchicalCullingManager:: CoherentHierarchicalCullingManager():
mAssumedVisibility(0), mThreshold(0)
{
        // initialise random generator because of assumed visibility
        srand(time(NULL));
}
//-----------------------------------------------------------------------
void CoherentHierarchicalCullingManager::RenderScene()
{
        QueryQueue queryQueue;
        unsigned int visiblePixels = 0;
        bool isAvailable = false;
        
        //-- PART 1: process finished occlusion queries
        while (!mHierarchyInterface->GetQueue()->empty() || !queryQueue.empty())
        {
                while (!queryQueue.empty() && 
                           queryQueue.front().second->GetQueryResult(visiblePixels, 
                                                                        mHierarchyInterface->GetQueue()->empty()))
                {
                HierarchyNode *node = queryQueue.front().first;
                        
                        queryQueue.pop();

                        if (visiblePixels > mVisibilityThreshold)
                        {
                                mHierarchyInterface->PullUpVisibility(node);
                                mHierarchyInterface->TraverseNode(node);
                        }
                        else
                        {       
                                mNumQueryCulledNodes ++;
                                
                                if(mVisualizeCulledNodes)
                                {
                                        mHierarchyInterface->VisualizeCulledNode(node, QUERY_CULLED);
                                }
                        }
                }
                
                //-- 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;
                                
                                if (mVisualizeCulledNodes)
                                {
                                        mHierarchyInterface->VisualizeCulledNode(node, FRUSTUM_CULLED);
                                }
                        }
                        else
                        {
                                // identify previously visible nodes
                                bool wasVisible = mHierarchyInterface->IsNodeVisible(node) && 
                                        (mHierarchyInterface->LastVisited(node) == mHierarchyInterface->GetFrameId() - 1);

                                // if node is assumed to be visible in this frame => skip query
                                // if intersects near plane => also skip query because wrong results possible
                                bool assumeVisible = intersects ||
                                        (wasVisible && (mAssumedVisibility > 0) && 
                                         mHierarchyInterface->HasGeometry(node) && DecideVisible(node));        

                                if (assumeVisible)
                                {
                                        // update node's visited flag
                                        mHierarchyInterface->SetLastVisited(node, mHierarchyInterface->GetFrameId());

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

                                        continue;
                                }

                // identify nodes that we cannot skip queries for
                                // geometry not only in leaves => test for renderable geometry
                                bool issueQuery = !wasVisible || mHierarchyInterface->HasGeometry(node);
                                                                
                                // reset node's visibility classification
                                mHierarchyInterface->SetNodeVisible(node, false);

                                // update node's visited flag
                                mHierarchyInterface->SetLastVisited(node, mHierarchyInterface->GetFrameId());
                        
                                // skip testing previously visible nodes without geometry
                                if (issueQuery)
                                {
                                        ++ mNumQueriesIssued;
                                        
                                        queryQueue.push(QueryPair(node, mHierarchyInterface->
                                                IssueOcclusionQuery(node, wasVisible)));
                                }
                                
                                // always traverse a node if it was visible
                                if (wasVisible)
                                {
                                        mHierarchyInterface->TraverseNode(node);
                                }
                        }
                }
        }
}
//-----------------------------------------------------------------------
void CoherentHierarchicalCullingManager::SetAssumedVisibility(unsigned int assumedVisibility)
{
        mAssumedVisibility = assumedVisibility;
        
        mThreshold = 0;

        if (mAssumedVisibility > 0)
        {
                mThreshold =  RAND_MAX - RAND_MAX / mAssumedVisibility;
        }
        //std::stringstream d; d << "*** setting assumed vis: " << mAssumedVisibility; Ogre::LogManager::getSingleton().logMessage(d.str());
}
//-----------------------------------------------------------------------
bool CoherentHierarchicalCullingManager::DecideVisible(HierarchyNode *node) const
{
        /*bool result = rand() < mThreshold;
        std::stringstream d; d << "Assumed vis: " << mAssumedVisibility << ", result: " << result;
        Ogre::LogManager::getSingleton().logMessage(d.str()); return result;*/
        
        return rand() < mThreshold;
}
} // namespace GtpVisibility