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

namespace GtpVisibility {

//-----------------------------------------------------------------------
void CoherentHierarchicalCullingManager::RenderScene()
{
	mNumFrustumCulledNodes = mNumQueryCulledNodes = 0;
//	OutputDebugString("Coherent Culling\n");

	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 ++;
			}
		}

		//-- 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, wasVisible)));
				}
					
				// always traverse a node if it was visible
				if (wasVisible)
				{
					mHierarchyInterface->TraverseNode(node);
				}
			}
		}
	}
}

} // namespace GtpVisibility