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

namespace GtpVisibility {

//-----------------------------------------------------------------------
CoherentHierarchicalCullingManager::CoherentHierarchicalCullingManager()
{
	SetAssumedVisibility(0);
	// initialise random generator in case we use assumed visibility
	srand(time(NULL));
}
//-----------------------------------------------------------------------
CoherentHierarchicalCullingManager::CoherentHierarchicalCullingManager(const unsigned int 
																		assumedVisibility)
{
	SetAssumedVisibility(assumedVisibility);
	// initialise random generator in case we use 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);
				}
			}
			// -- if node intersects near plane, skip query because wrong results possible
			else if (intersects)
			{
				SkipQuery(node);
			}
			else
			{
				// identify previously visible nodes
				bool wasVisible = mHierarchyInterface->IsNodeVisible(node) && 
					(mHierarchyInterface->LastVisited(node) == mHierarchyInterface->GetFrameId() - 1);
					
				// if we assume node to be visible in this frame => skip query 
				if (wasVisible && (mAssumedVisibility > 0) &&  DecideVisible(node))// && mHierarchyInterface->HasGeometry(node))
				{
					SkipQuery(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;
}
//-----------------------------------------------------------------------
void CoherentHierarchicalCullingManager::SkipQuery(HierarchyNode *node)
{
	// -- set node to be visible in this frame, then traverse it
	mHierarchyInterface->SetLastVisited(node, mHierarchyInterface->GetFrameId());

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

} // namespace GtpVisibility