polyvox/tests/TestSurfaceExtractor.cpp

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#include "TestSurfaceExtractor.h"

#include "PolyVox/Density.h"
#include "PolyVox/FilePager.h"
#include "PolyVox/MaterialDensityPair.h"
#include "PolyVox/RawVolume.h"
#include "PolyVox/PagedVolume.h"
#include "PolyVox/MarchingCubesSurfaceExtractor.h"

#include <QtTest>

#include <random>

using namespace PolyVox;

// Test our ability to modify the behaviour of the MarchingCubesSurfaceExtractor. This simple example only modifies
// the threshold (and actually this can be achieved by passing a parameter to the constructor of the
// DefaultMarchingCubesController) but you could implement custom behaviour in the other members
// if you wanted too. Actually, it's not clear if this ability is really useful because I can't think
// what you'd modify apart from the threshold but the ability is at least available. Also, the
// DefaultMarchingCubesController is templatised whereas this exmple shows that controllers don't
// have to be.
class CustomMarchingCubesController
{
public:
	typedef float DensityType;
	typedef float MaterialType;

	float convertToDensity(float voxel)
	{
		return voxel;
	}

	float convertToMaterial(float /*voxel*/)
	{
		return 1.0f;
	}

	float blendMaterials(float /*a*/, float /*b*/, float /*weight*/)
	{
		return 1.0f;
	}

	float getThreshold(void)
	{
		return 50.0f;
	}
};

// These 'writeDensityValueToVoxel' functions provide a unified interface for writting densities to primative and class voxel types.
// They are conceptually the inverse of the 'convertToDensity' function used by the MarchingCubesSurfaceExtractor. They probably shouldn't be part
// of PolyVox, but they might be usful to other tests so we cold move them into a 'Tests.h' or something in the future.
template<typename VoxelType>
void writeDensityValueToVoxel(int valueToWrite, VoxelType& voxel)
{
	voxel = valueToWrite;
}

template<>
void writeDensityValueToVoxel(int valueToWrite, MaterialDensityPair88& voxel)
{
	voxel.setDensity(valueToWrite);
}

template<typename VoxelType>
void writeMaterialValueToVoxel(int /*valueToWrite*/, VoxelType& /*voxel*/)
{
	//Most types don't have a material
	return;
}

template<>
void writeMaterialValueToVoxel(int valueToWrite, MaterialDensityPair88& voxel)
{
	voxel.setMaterial(valueToWrite);
}

template <typename VolumeType>
VolumeType* createAndFillVolume(void)
{
	const int32_t uVolumeSideLength = 64;

	FilePager<typename VolumeType::VoxelType>* pager = new FilePager<typename VolumeType::VoxelType>(".");

	//Create empty volume
	VolumeType* volData = new VolumeType(Region(Vector3DInt32(0, 0, 0), Vector3DInt32(uVolumeSideLength - 1, uVolumeSideLength - 1, uVolumeSideLength - 1)), pager);

	// Fill
	for (int32_t z = 0; z < uVolumeSideLength; z++)
	{
		for (int32_t y = 0; y < uVolumeSideLength; y++)
		{
			for (int32_t x = 0; x < uVolumeSideLength; x++)
			{
				// Create a density field which changes throughout the volume. It's
				// zero in the lower corner and increasing as the coordinates increase.
				typename VolumeType::VoxelType voxelValue;
				writeDensityValueToVoxel<typename VolumeType::VoxelType>(x + y + z, voxelValue);
				writeMaterialValueToVoxel<typename VolumeType::VoxelType>(z > uVolumeSideLength / 2 ? 42 : 79, voxelValue);
				volData->setVoxelAt(x, y, z, voxelValue);
			}
		}
	}

	return volData;
}

// From http://stackoverflow.com/a/5289624
float randomFloat(float a, float b)
{
	float random = ((float)rand()) / (float)RAND_MAX;
	float diff = b - a;
	float r = random * diff;
	return a + r;
}

template <typename VolumeType>
VolumeType* createAndFillVolumeWithNoise(int32_t iVolumeSideLength, float minValue, float maxValue)
{
	FilePager<float>* pager = new FilePager<float>(".");

	//Create empty volume
	VolumeType* volData = new VolumeType(Region(Vector3DInt32(0, 0, 0), Vector3DInt32(iVolumeSideLength - 1, iVolumeSideLength - 1, iVolumeSideLength - 1)), pager);

	// Set up a random number generator
	std::mt19937 rng;
	std::uniform_real_distribution<float> dist(minValue, maxValue);

	// Fill
	for (int32_t z = 0; z < iVolumeSideLength; z++)
	{
		for (int32_t y = 0; y < iVolumeSideLength; y++)
		{
			for (int32_t x = 0; x < iVolumeSideLength; x++)
			{
				float voxelValue = dist(rng);
				volData->setVoxelAt(x, y, z, voxelValue);
			}
		}
	}

	return volData;
}

void TestSurfaceExtractor::testBehaviour()
{
	// These tests apply the Marching Cubes surface extractor to volumes of various voxel types. In addition we sometimes make use of custom controllers
	// and user-provided meshes to make sure these various combinations work as expected.
	//
	// It is also noted that the number of indices and vertices is varying quite significantly based on the voxel type. This seems unexpected, but could
	// be explained if some overflow is occuring when writing data into the volume, causing volumes of different voxel types to have different distributions.
	// Of course, the use of a custom controller will also make a significant diference, but this probably does need investigating further in the future.

	// This basic test just uses the default controller and automatically generates a mesh of the appropriate type.
	auto uintVol = createAndFillVolume< PagedVolume<uint8_t> >();
	auto uintMesh = extractMarchingCubesMesh(uintVol, uintVol->getEnclosingRegion());
	QCOMPARE(uintMesh.getNoOfVertices(), uint32_t(12096)); // Verifies size of mesh and that we have 32-bit indices
	QCOMPARE(uintMesh.getNoOfIndices(), uint32_t(35157)); // Verifies size of mesh
	QCOMPARE(uintMesh.getIndex(100), uint32_t(44)); // Verifies that we have 32-bit indices
	QCOMPARE(uintMesh.getVertex(100).data, uint8_t(1)); // Not really meaningful for a primative type

	// This test makes use of a custom controller
	auto floatVol = createAndFillVolume< PagedVolume<float> >();
	CustomMarchingCubesController floatCustomController;
	auto floatMesh = extractMarchingCubesMesh(floatVol, floatVol->getEnclosingRegion(), floatCustomController);
	QCOMPARE(floatMesh.getNoOfVertices(), uint32_t(16113)); // Verifies size of mesh and that we have 32-bit indices
	QCOMPARE(floatMesh.getNoOfIndices(), uint32_t(22053)); // Verifies size of mesh
	QCOMPARE(floatMesh.getIndex(100), uint32_t(26)); // Verifies that we have 32-bit indices
	QCOMPARE(floatMesh.getVertex(100).data, float(1.0f)); // Not really meaningful for a primative type

	// This test makes use of a user provided mesh. It uses the default controller, but we have to explicitly provide this because C++ won't let us
	// use a default for the second-to-last parameter but noot use a default for the last parameter.
	auto intVol = createAndFillVolume< PagedVolume<int8_t> >();
	Mesh< MarchingCubesVertex< int8_t >, uint16_t > intMesh;
	extractMarchingCubesMeshCustom(intVol, intVol->getEnclosingRegion(), &intMesh);
	QCOMPARE(intMesh.getNoOfVertices(), uint16_t(11718)); // Verifies size of mesh and that we have 16-bit indices
	QCOMPARE(intMesh.getNoOfIndices(), uint32_t(34041)); // Verifies size of mesh
	QCOMPARE(intMesh.getIndex(100), uint16_t(29)); // Verifies that we have 16-bit indices
	QCOMPARE(intMesh.getVertex(100).data, int8_t(1)); // Not really meaningful for a primative type

	// This test makes use of a user-provided mesh and also a custom controller.
	auto doubleVol = createAndFillVolume< PagedVolume<double> >();
	CustomMarchingCubesController doubleCustomController;
	Mesh< MarchingCubesVertex< double >, uint16_t > doubleMesh;
	extractMarchingCubesMeshCustom(doubleVol, doubleVol->getEnclosingRegion(), &doubleMesh, doubleCustomController);
	QCOMPARE(doubleMesh.getNoOfVertices(), uint16_t(16113)); // Verifies size of mesh and that we have 32-bit indices
	QCOMPARE(doubleMesh.getNoOfIndices(), uint32_t(22053)); // Verifies size of mesh
	QCOMPARE(doubleMesh.getIndex(100), uint16_t(26)); // Verifies that we have 32-bit indices
	QCOMPARE(doubleMesh.getVertex(100).data, double(1.0f)); // Not really meaningful for a primative type

	// This test ensures the extractor works on a non-primitive voxel type.
	auto materialVol = createAndFillVolume< PagedVolume<MaterialDensityPair88> >();
	auto materialMesh = extractMarchingCubesMesh(materialVol, materialVol->getEnclosingRegion());
	QCOMPARE(materialMesh.getNoOfVertices(), uint32_t(12096)); // Verifies size of mesh and that we have 32-bit indices
	QCOMPARE(materialMesh.getNoOfIndices(), uint32_t(35157)); // Verifies size of mesh
	QCOMPARE(materialMesh.getIndex(100), uint32_t(44)); // Verifies that we have 32-bit indices
	QCOMPARE(materialMesh.getVertex(100).data.getMaterial(), uint16_t(79)); // Verify the data attached to the vertex
}

void TestSurfaceExtractor::testEmptyVolumePerformance()
{
	auto emptyVol = createAndFillVolumeWithNoise< PagedVolume<float> >(128, -2.0f, -1.0f);
	Mesh< MarchingCubesVertex< float >, uint16_t > emptyMesh;
	QBENCHMARK{ extractMarchingCubesMeshCustom(emptyVol, Region(32, 32, 32, 63, 63, 63), &emptyMesh); }
	QCOMPARE(emptyMesh.getNoOfVertices(), uint16_t(0));
}

void TestSurfaceExtractor::testNoiseVolumePerformance()
{
	auto noiseVol = createAndFillVolumeWithNoise< PagedVolume<float> >(128, -1.0f, 1.0f);
	Mesh< MarchingCubesVertex< float >, uint16_t > noiseMesh;
	QBENCHMARK{ extractMarchingCubesMeshCustom(noiseVol, Region(32, 32, 32, 63, 63, 63), &noiseMesh); }
	QCOMPARE(noiseMesh.getNoOfVertices(), uint16_t(48704));
}

QTEST_MAIN(TestSurfaceExtractor)