polyvox/examples/Paging/main.cpp

/*******************************************************************************
The MIT License (MIT)

Copyright (c) 2015 David Williams and Matthew Williams

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#include "PolyVoxExample.h"
#include "Perlin.h"

#include "PolyVox/MaterialDensityPair.h"
#include "PolyVox/CubicSurfaceExtractor.h"
#include "PolyVox/MarchingCubesSurfaceExtractor.h"
#include "PolyVox/Mesh.h"
#include "PolyVox/PagedVolume.h"

#include <QApplication>

// Use the PolyVox namespace
using namespace PolyVox;

/**
 * Generates data using Perlin noise.
 */
class PerlinNoisePager : public PolyVox::PagedVolume<MaterialDensityPair44>::Pager
{
public:
	/// Constructor
	PerlinNoisePager()
		:PagedVolume<MaterialDensityPair44>::Pager()
	{
	}

	/// Destructor
	virtual ~PerlinNoisePager() {};

	virtual void pageIn(const PolyVox::Region& region, PagedVolume<MaterialDensityPair44>::Chunk* pChunk)
	{
		Perlin perlin(2,2,1,234);

		for(int x = region.getLowerX(); x <= region.getUpperX(); x++)
		{
			for(int y = region.getLowerY(); y <= region.getUpperY(); y++)
			{
				float perlinVal = perlin.Get(x / static_cast<float>(255-1), y / static_cast<float>(255-1));
				perlinVal += 1.0f;
				perlinVal *= 0.5f;
				perlinVal *= 255;
				for(int z = region.getLowerZ(); z <= region.getUpperZ(); z++)
				{
					MaterialDensityPair44 voxel;
					if(z < perlinVal)
					{
						const int xpos = 50;
						const int zpos = 100;
						if((x-xpos)*(x-xpos) + (z-zpos)*(z-zpos) < 200)
						{
							// tunnel
							voxel.setMaterial(0);
							voxel.setDensity(MaterialDensityPair44::getMinDensity());
						} else
						{
							// solid
							voxel.setMaterial(245);
							voxel.setDensity(MaterialDensityPair44::getMaxDensity());
						}
					}
					else
					{
						voxel.setMaterial(0);
						voxel.setDensity(MaterialDensityPair44::getMinDensity());
					}

					// Voxel position within a chunk always start from zero. So if a chunk represents region (4, 8, 12) to (11, 19, 15)
					// then the valid chunk voxels are from (0, 0, 0) to (7, 11, 3). Hence we subtract the lower corner position of the
					// region from the volume space position in order to get the chunk space position.
					pChunk->setVoxel(x - region.getLowerX(), y - region.getLowerY(), z - region.getLowerZ(), voxel);
				}
			}
		}
	}

	virtual void pageOut(const PolyVox::Region& region, PagedVolume<MaterialDensityPair44>::Chunk* /*pChunk*/)
	{
		std::cout << "warning unloading region: " << region.getLowerCorner() << " -> " << region.getUpperCorner() << std::endl;
	}
};

class PagingExample : public PolyVoxExample
{
public:
	PagingExample(QWidget *parent)
		:PolyVoxExample(parent)
	{
	}

protected:
	void initializeExample() override
	{
		PerlinNoisePager* pager = new PerlinNoisePager();
		PagedVolume<MaterialDensityPair44> volData(pager, 8 * 1024 * 1024, 64);

		// Just some tests of memory usage, etc. 
		std::cout << "Memory usage: " << (volData.calculateSizeInBytes() / 1024.0 / 1024.0) << "MB" << std::endl;
		PolyVox::Region reg(Vector3DInt32(-255, 0, 0), Vector3DInt32(255, 255, 255));
		std::cout << "Prefetching region: " << reg.getLowerCorner() << " -> " << reg.getUpperCorner() << std::endl;
		volData.prefetch(reg);
		std::cout << "Memory usage: " << (volData.calculateSizeInBytes() / 1024.0 / 1024.0) << "MB" << std::endl;
		std::cout << "Flushing entire volume" << std::endl;
		volData.flushAll();
		std::cout << "Memory usage: " << (volData.calculateSizeInBytes() / 1024.0 / 1024.0) << "MB" << std::endl;

		// Extract the surface
		PolyVox::Region reg2(Vector3DInt32(0, 0, 0), Vector3DInt32(254, 254, 254));
		auto mesh = extractCubicMesh(&volData, reg2);
		std::cout << "#vertices: " << mesh.getNoOfVertices() << std::endl;

		auto decodedMesh = decodeMesh(mesh);

		// Pass the surface to the OpenGL window
		addMesh(decodedMesh);

		setCameraTransform(QVector3D(300.0f, 300.0f, 300.0f), -(PI / 4.0f), PI + (PI / 4.0f));
	}
};

int main(int argc, char *argv[])
{
	// Create and show the Qt OpenGL window
	QApplication app(argc, argv);
	PagingExample openGLWidget(0);
	openGLWidget.show();

	// Run the message pump.
	return app.exec();
}