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#include "TestRaycast.h"

#include "PolyVox/Density.h"
#include "PolyVox/Raycast.h"
#include "PolyVox/RawVolume.h"

#include "PolyVox/Impl/RandomUnitVectors.h"

#include <QtTest>

using namespace PolyVox;

// This is the callback functor which is called by the raycast() function for every voxel it touches.
// It's primary purpose is to tell the raycast whether or not to continue (i.e. it tests whether the
// ray has hit a solid voxel). Because the instance of this class is passed to the raycast() function
// by reference we can also use it to encapsulate some state. We're testing this by counting the total
// number of voxels touched.
class RaycastTestFunctor
{
public:
	RaycastTestFunctor()
		:m_uVoxelsTouched(0)
		,m_bRayLeftVolume(false)
	{
	}

	bool operator()(const RawVolume<int8_t>::Sampler& sampler)
	{
		m_uVoxelsTouched++;

		// For this particular test we know that we are always starting a ray inside the volume,
		// so if it ever leaves the volume we know it can't go back in and so we can terminate early.
		// This optimisation is worthwhile because samplers get slow once outside the volume.
		if(!sampler.isCurrentPositionValid())
		{
			m_bRayLeftVolume = true;
			return false;
		}

		// We are in the volume, so decide whether to continue based on the voxel value.
		return sampler.getVoxel() <= 0;
	}

	uint32_t m_uVoxelsTouched;
	bool m_bRayLeftVolume;
};

void TestRaycast::testExecute()
{
	const int32_t uVolumeSideLength = 32;

	//Create a hollow volume, with solid sides on x and y but with open ends in z.
	RawVolume<int8_t> volData(Region(Vector3DInt32(0, 0, 0), Vector3DInt32(uVolumeSideLength - 1, uVolumeSideLength - 1, uVolumeSideLength - 1)));
	for (int32_t z = 0; z < uVolumeSideLength; z++)
	{
		for (int32_t y = 0; y < uVolumeSideLength; y++)
		{
			for (int32_t x = 0; x < uVolumeSideLength; x++)
			{
				if((x == 0) || (x == uVolumeSideLength-1) || (y == 0) || (y == uVolumeSideLength-1))
				{
					volData.setVoxel(x, y, z, 100);
				}
				else
				{
					volData.setVoxel(x, y, z, -100);
				}				
			}
		}
	}

	//Cast rays from the centre. Roughly 2/3 should escape.
	Vector3DFloat start (uVolumeSideLength / 2, uVolumeSideLength / 2, uVolumeSideLength / 2);	

	// We could have counted the total number of hits in the same way as the total number of voxels
	// touched, but for demonstration and testing purposes we are making use of the raycast return value
	// and counting them seperatly in this variable.
	int hits = 0;
	uint32_t uTotalVoxelsTouched = 0;

	// Cast a large number of random rays
	for(int ct = 0; ct < 1000000; ct++)
	{
		RaycastTestFunctor raycastTestFunctor;
		RaycastResult result = raycastWithDirection(&volData, start, randomUnitVectors[ct % 1024] * 1000.0f, raycastTestFunctor);

		uTotalVoxelsTouched += raycastTestFunctor.m_uVoxelsTouched;

		// If the raycast completed then we know it did not hit anything.If it was interupted then it
		// probably hit something, unless we noted that the reason it was interupted was that it left the volume.
		if((result == RaycastResults::Interupted) && (raycastTestFunctor.m_bRayLeftVolume == false))
		{
			hits++;
		}
	}	

	// Check the number of hits.
	QCOMPARE(hits, 687494);

	// Check the total number of voxels touched
	QCOMPARE(uTotalVoxelsTouched, static_cast<uint32_t>(29783248));
}

QTEST_MAIN(TestRaycast)