#include "CoherentHierarchicalCullingManager.h"

namespace GtpVisibility {

//-----------------------------------------------------------------------
CoherentHierarchicalCullingManager::CoherentHierarchicalCullingManager(HierarchyInterface *hierarchyInterface):
CullingManager(hierarchyInterface)
{
}
//-----------------------------------------------------------------------
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 ++;
				continue;
			}

			// 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