#include "OgreGpuCommandBufferFlush.h"
#include "OgreRoot.h"
#include "OgreRenderSystem.h"
#include "OgreHardwareOcclusionQuery.h"

namespace Ogre
{
	//---------------------------------------------------------------------
	GpuCommandBufferFlush::GpuCommandBufferFlush()
		: mUseOcclusionQuery(true)
		, mMaxQueuedFrames(2)
		, mCurrentFrame(0)
		, mStartPull(false)
		, mStarted(false)
	{

	}
	//---------------------------------------------------------------------
	GpuCommandBufferFlush::~GpuCommandBufferFlush()
	{
		stop();
	}
	//---------------------------------------------------------------------
	void GpuCommandBufferFlush::start(size_t maxQueuedFrames)
	{
		if (!Root::getSingletonPtr() || !Root::getSingletonPtr()->getRenderSystem())
			return;

		stop();
		mMaxQueuedFrames = maxQueuedFrames;
		RenderSystem* rsys = Root::getSingleton().getRenderSystem();
		mUseOcclusionQuery = rsys->getCapabilities()->hasCapability(RSC_HWOCCLUSION);

		if (mUseOcclusionQuery)
		{
			for (size_t i = 0; i < mMaxQueuedFrames; ++i)
			{
				HardwareOcclusionQuery* hoq = rsys->createHardwareOcclusionQuery();
				mHOQList.push_back(hoq);
			}
		}

		mCurrentFrame = 0;
		mStartPull = false;

		Root::getSingleton().addFrameListener(this);

		mStarted = true;

	}
	//---------------------------------------------------------------------
	void GpuCommandBufferFlush::stop()
	{
		if (!mStarted || !Root::getSingletonPtr() || !Root::getSingletonPtr()->getRenderSystem())
			return;

		RenderSystem* rsys = Root::getSingleton().getRenderSystem();
		for (HOQList::iterator i = mHOQList.begin(); i != mHOQList.end(); ++i)
		{
			rsys->destroyHardwareOcclusionQuery(*i);
		}
		mHOQList.clear();

		Root::getSingleton().removeFrameListener(this);

		mStarted = false;

	}
	//---------------------------------------------------------------------
	bool GpuCommandBufferFlush::frameStarted(const FrameEvent& evt)
	{
		if (mUseOcclusionQuery)
		{

			mHOQList[mCurrentFrame]->beginOcclusionQuery();

		}

		return true;
	}
	//---------------------------------------------------------------------
	bool GpuCommandBufferFlush::frameEnded(const FrameEvent& evt)
	{
		if (mUseOcclusionQuery)
		{
			mHOQList[mCurrentFrame]->endOcclusionQuery();
		}
		mCurrentFrame = (mCurrentFrame + 1) % mMaxQueuedFrames;
		// If we've wrapped around, time to start pulling
		if (mCurrentFrame == 0)
			mStartPull = true;

		if (mStartPull)
		{
			unsigned int dummy;
			mHOQList[mCurrentFrame]->pullOcclusionQuery(&dummy);
		}

		return true;
	}
	//---------------------------------------------------------------------


}