e89a55d154
I didn't apply the changes to a few macro-heavy files as Visual Studio removes all indentation from macros, whereas the indentation can be handy to see nesting.
335 lines
16 KiB
C++
335 lines
16 KiB
C++
/*******************************************************************************
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* The MIT License (MIT)
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*
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* Copyright (c) 2015 David Williams and Matthew Williams
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in all
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* copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*******************************************************************************/
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#ifndef __PolyVox_PagedVolume_H__
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#define __PolyVox_PagedVolume_H__
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#include "BaseVolume.h"
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#include "Region.h"
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#include "Vector.h"
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#include <limits>
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#include <cstdlib> //For abort()
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#include <cstring> //For memcpy
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#include <unordered_map>
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#include <list>
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#include <map>
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#include <memory>
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#include <stdexcept> //For invalid_argument
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#include <vector>
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namespace PolyVox
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{
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/// The PagedVolume class provides a memory efficient method of storing voxel data while also allowing fast access and modification.
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////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
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/// A PagedVolume is essentially a 3D array in which each element (or <i>voxel</i>) is identified by a three dimensional (x,y,z) coordinate.
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/// We use the PagedVolume class to store our data in an efficient way, and it is the input to many of the algorithms (such as the surface
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/// extractors) which form the heart of PolyVox. The PagedVolume class is templatised so that different types of data can be stored within each voxel.
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///
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/// Basic usage
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/// -----------
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///
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/// The following code snippet shows how to construct a volume and demonstrates basic usage:
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///
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/// \code
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/// PagedVolume<int> volume(Region(Vector3DInt32(0,0,0), Vector3DInt32(63,127,255)));
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/// volume.setVoxel(15, 90, 42, int(5));
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/// std::cout << "Voxel at (15, 90, 42) has value: " << volume.getVoxel(15, 90, 42) << std::endl;
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/// std::cout << "Width = " << volume.getWidth() << ", Height = " << volume.getHeight() << ", Depth = " << volume.getDepth() << std::endl;
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/// \endcode
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///
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/// The PagedVolume constructor takes a Region as a parameter. This specifies the valid range of voxels which can be held in the volume, so in this
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/// particular case the valid voxel positions are (0,0,0) to (63, 127, 255). The result of attempts to access voxels outside this range will result
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/// are defined by the WrapMode). PolyVox also has support for near infinite volumes which will be discussed later.
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///
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/// Access to individual voxels is provided via the setVoxel() and getVoxel() member functions. Advanced users may also be interested in
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/// the Sampler nested class for faster read-only access to a large number of voxels.
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///
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/// Lastly the example prints out some properties of the PagedVolume. Note that the dimentsions getWidth(), getHeight(), and getDepth() are inclusive, such
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/// that the width is 64 when the range of valid x coordinates goes from 0 to 63.
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///
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/// Data Representaion
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/// ------------------
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/// If stored carelessly, volume data can take up a huge amount of memory. For example, a volume of dimensions 1024x1024x1024 with
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/// 1 byte per voxel will require 1GB of memory if stored in an uncompressed form. Natuarally our PagedVolume class is much more efficient
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/// than this and it is worth understanding (at least at a high level) the approach which is used.
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///
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/// Essentially, the PagedVolume class stores its data as a collection of chunks. Each of these chunk is much smaller than the whole volume,
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/// for example a typical size might be 32x32x32 voxels (though is is configurable by the user). In this case, a 256x512x1024 volume
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/// would contain 8x16x32 = 4096 chunks. Typically these chunks do not need to all be in memory all the time, and the Pager class can
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/// be used to control how they are loaded and unloaded. This mechanism allows a
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/// potentially unlimited amount of data to be loaded, provided the user is able to take responsibility for storing any data which PolyVox
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/// cannot fit in memory, and then returning it back to PolyVox on demand. For example, the user might choose to temporarily store this data
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/// on disk or stream it to a remote database.
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///
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/// Essentially you are providing an extension to the PagedVolume class - a way for data to be stored once PolyVox has run out of memory for it. Note
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/// that you don't actually have to do anything with the data - you could simply decide that once it gets removed from memory it doesn't matter
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/// anymore.
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///
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/// Cache-aware traversal
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/// ---------------------
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/// *NOTE: This needs updating for PagedVolume rather than the old LargeVolume*
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/// You might be suprised at just how many cache misses can occur when you traverse the volume in a naive manner. Consider a 1024x1024x1024 volume
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/// with chunks of size 32x32x32. And imagine you iterate over this volume with a simple three-level for loop which iterates over x, the y, then z.
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/// If you start at position (0,0,0) then ny the time you reach position (1023,0,0) you have touched 1024 voxels along one edge of the volume and
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/// have pulled 32 chunks into the cache. By the time you reach (1023,1023,0) you have hit 1024x1024 voxels and pulled 32x32 chunks into the cache.
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/// You are now ready to touch voxel (0,0,1) which is right next to where you started, but unless your cache is at least 32x32 chunks large then this
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/// initial chunk has already been cleared from the cache.
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///
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/// Ensuring you have a large enough cache size can obviously help the above situation, but you might also consider iterating over the voxels in a
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/// different order. For example, if you replace your three-level loop with a six-level loop then you can first process all the voxels between (0,0,0)
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/// and (31,31,31), then process all the voxels between (32,0,0) and (63,0,0), and so forth. Using this approach you will have no cache misses even
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/// is your cache size is only one. Of course the logic is more complex, but writing code in such a cache-aware manner may be beneficial in some situations.
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///
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/// Threading
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/// ---------
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/// The PagedVolume class does not make any guarentees about thread safety. You should ensure that all accesses are performed from the same thread.
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/// This is true even if you are only reading data from the volume, as concurrently reading from different threads can invalidate the contents
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/// of the chunk cache (amoung other problems).
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////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
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template <typename VoxelType>
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class PagedVolume : public BaseVolume<VoxelType>
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{
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public:
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/// The PagedVolume stores it data as a set of Chunk instances which can be loaded and unloaded as memory requirements dictate.
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class Chunk;
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/// The Pager class is responsible for the loading and unloading of Chunks, and can be overridden by the user.
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class Pager;
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class Chunk
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{
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friend class PagedVolume;
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public:
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Chunk(Vector3DInt32 v3dPosition, uint16_t uSideLength, Pager* pPager = nullptr);
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~Chunk();
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VoxelType* getData(void) const;
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uint32_t getDataSizeInBytes(void) const;
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VoxelType getVoxel(uint32_t uXPos, uint32_t uYPos, uint32_t uZPos) const;
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VoxelType getVoxel(const Vector3DUint16& v3dPos) const;
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void setVoxel(uint32_t uXPos, uint32_t uYPos, uint32_t uZPos, VoxelType tValue);
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void setVoxel(const Vector3DUint16& v3dPos, VoxelType tValue);
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void changeLinearOrderingToMorton(void);
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void changeMortonOrderingToLinear(void);
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private:
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/// Private copy constructor to prevent accisdental copying
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Chunk(const Chunk& /*rhs*/) {};
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/// Private assignment operator to prevent accisdental copying
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Chunk& operator=(const Chunk& /*rhs*/) {};
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// This is updated by the PagedVolume and used to discard the least recently used chunks.
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uint32_t m_uChunkLastAccessed;
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// This is so we can tell whether a uncompressed chunk has to be recompressed and whether
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// a compressed chunk has to be paged back to disk, or whether they can just be discarded.
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bool m_bDataModified;
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uint32_t calculateSizeInBytes(void);
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static uint32_t calculateSizeInBytes(uint32_t uSideLength);
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VoxelType* m_tData;
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uint16_t m_uSideLength;
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uint8_t m_uSideLengthPower;
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Pager* m_pPager;
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// Note: Do we really need to store this position here as well as in the block maps?
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Vector3DInt32 m_v3dChunkSpacePosition;
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};
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/**
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* Users can override this class and provide an instance of the derived class to the PagedVolume constructor. This derived class
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* could then perform tasks such as compression and decompression of the data, and read/writing it to a file, database, network,
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* or other storage as appropriate. See FilePager for a simple example of such a derived class.
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*/
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class Pager
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{
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public:
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/// Constructor
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Pager() {};
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/// Destructor
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virtual ~Pager() {};
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virtual void pageIn(const Region& region, Chunk* pChunk) = 0;
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virtual void pageOut(const Region& region, Chunk* pChunk) = 0;
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};
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//There seems to be some descrepency between Visual Studio and GCC about how the following class should be declared.
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//There is a work around (see also See http://goo.gl/qu1wn) given below which appears to work on VS2010 and GCC, but
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//which seems to cause internal compiler errors on VS2008 when building with the /Gm 'Enable Minimal Rebuild' compiler
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//option. For now it seems best to 'fix' it with the preprocessor insstead, but maybe the workaround can be reinstated
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//in the future
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//typedef Volume<VoxelType> VolumeOfVoxelType; //Workaround for GCC/VS2010 differences.
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//class Sampler : public VolumeOfVoxelType::template Sampler< PagedVolume<VoxelType> >
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#ifndef SWIG
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#if defined(_MSC_VER)
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class Sampler : public BaseVolume<VoxelType>::Sampler< PagedVolume<VoxelType> > //This line works on VS2010
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#else
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class Sampler : public BaseVolume<VoxelType>::template Sampler< PagedVolume<VoxelType> > //This line works on GCC
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#endif
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{
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public:
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Sampler(PagedVolume<VoxelType>* volume);
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~Sampler();
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inline VoxelType getVoxel(void) const;
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void setPosition(const Vector3DInt32& v3dNewPos);
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void setPosition(int32_t xPos, int32_t yPos, int32_t zPos);
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inline bool setVoxel(VoxelType tValue);
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void movePositiveX(void);
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void movePositiveY(void);
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void movePositiveZ(void);
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void moveNegativeX(void);
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void moveNegativeY(void);
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void moveNegativeZ(void);
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inline VoxelType peekVoxel1nx1ny1nz(void) const;
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inline VoxelType peekVoxel1nx1ny0pz(void) const;
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inline VoxelType peekVoxel1nx1ny1pz(void) const;
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inline VoxelType peekVoxel1nx0py1nz(void) const;
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inline VoxelType peekVoxel1nx0py0pz(void) const;
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inline VoxelType peekVoxel1nx0py1pz(void) const;
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inline VoxelType peekVoxel1nx1py1nz(void) const;
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inline VoxelType peekVoxel1nx1py0pz(void) const;
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inline VoxelType peekVoxel1nx1py1pz(void) const;
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inline VoxelType peekVoxel0px1ny1nz(void) const;
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inline VoxelType peekVoxel0px1ny0pz(void) const;
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inline VoxelType peekVoxel0px1ny1pz(void) const;
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inline VoxelType peekVoxel0px0py1nz(void) const;
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inline VoxelType peekVoxel0px0py0pz(void) const;
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inline VoxelType peekVoxel0px0py1pz(void) const;
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inline VoxelType peekVoxel0px1py1nz(void) const;
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inline VoxelType peekVoxel0px1py0pz(void) const;
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inline VoxelType peekVoxel0px1py1pz(void) const;
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inline VoxelType peekVoxel1px1ny1nz(void) const;
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inline VoxelType peekVoxel1px1ny0pz(void) const;
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inline VoxelType peekVoxel1px1ny1pz(void) const;
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inline VoxelType peekVoxel1px0py1nz(void) const;
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inline VoxelType peekVoxel1px0py0pz(void) const;
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inline VoxelType peekVoxel1px0py1pz(void) const;
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inline VoxelType peekVoxel1px1py1nz(void) const;
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inline VoxelType peekVoxel1px1py0pz(void) const;
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inline VoxelType peekVoxel1px1py1pz(void) const;
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private:
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//Other current position information
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VoxelType* mCurrentVoxel;
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uint16_t m_uXPosInChunk;
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uint16_t m_uYPosInChunk;
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uint16_t m_uZPosInChunk;
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// This should ideally be const, but that prevent automatic generation of an assignment operator (https://goo.gl/Sn7KpZ).
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// We could provide one manually, but it's currently unused so there is no real test for if it works. I'm putting
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// together a new release at the moment so I'd rathern not make 'risky' changes.
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uint16_t m_uChunkSideLengthMinusOne;
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};
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#endif // SWIG
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public:
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/// Constructor for creating a fixed size volume.
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PagedVolume(Pager* pPager, uint32_t uTargetMemoryUsageInBytes = 256 * 1024 * 1024, uint16_t uChunkSideLength = 32);
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/// Destructor
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~PagedVolume();
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/// Gets a voxel at the position given by <tt>x,y,z</tt> coordinates
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VoxelType getVoxel(int32_t uXPos, int32_t uYPos, int32_t uZPos) const;
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/// Gets a voxel at the position given by a 3D vector
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VoxelType getVoxel(const Vector3DInt32& v3dPos) const;
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/// Sets the voxel at the position given by <tt>x,y,z</tt> coordinates
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void setVoxel(int32_t uXPos, int32_t uYPos, int32_t uZPos, VoxelType tValue);
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/// Sets the voxel at the position given by a 3D vector
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void setVoxel(const Vector3DInt32& v3dPos, VoxelType tValue);
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/// Tries to ensure that the voxels within the specified Region are loaded into memory.
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void prefetch(Region regPrefetch);
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/// Ensures that any voxels within the specified Region are removed from memory.
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//void flush(Region regFlush);
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/// Removes all voxels from memory
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void flushAll();
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/// Calculates approximatly how many bytes of memory the volume is currently using.
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uint32_t calculateSizeInBytes(void);
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protected:
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/// Copy constructor
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PagedVolume(const PagedVolume& rhs);
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/// Assignment operator
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PagedVolume& operator=(const PagedVolume& rhs);
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private:
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bool canReuseLastAccessedChunk(int32_t iChunkX, int32_t iChunkY, int32_t iChunkZ) const;
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Chunk* getChunk(int32_t uChunkX, int32_t uChunkY, int32_t uChunkZ) const;
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// Storing these properties individually has proved to be faster than keeping
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// them in a Vector3DInt32 as it avoids constructions and comparison overheads.
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// They are also at the start of the class in the hope that they will be pulled
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// into cache - I've got no idea if this actually makes a difference.
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mutable int32_t m_v3dLastAccessedChunkX = 0;
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mutable int32_t m_v3dLastAccessedChunkY = 0;
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mutable int32_t m_v3dLastAccessedChunkZ = 0;
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mutable Chunk* m_pLastAccessedChunk = nullptr;
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mutable uint32_t m_uTimestamper = 0;
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uint32_t m_uChunkCountLimit = 0;
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// Chunks are stored in the following array which is used as a hash-table. Conventional wisdom is that such a hash-table
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// should not be more than half full to avoid conflicts, and a practical chunk size seems to be 64^3. With this configuration
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// there can be up to 32768*64^3 = 8 gigavoxels (with each voxel perhaps being many bytes). This should effectively make use
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// of even high end machines. Of course, the user can choose to limit the memory usage in which case much less of the chunk
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// array will actually be used. None-the-less, we have chosen to use a fixed size array (rather than a vector) as it appears to
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// be slightly faster (probably due to the extra pointer indirection in a vector?) and the actual size of this array should
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// just be 1Mb or so.
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static const uint32_t uChunkArraySize = 65536;
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mutable std::unique_ptr< Chunk > m_arrayChunks[uChunkArraySize];
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// The size of the chunks
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uint16_t m_uChunkSideLength;
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uint8_t m_uChunkSideLengthPower;
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int32_t m_iChunkMask;
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Pager* m_pPager = nullptr;
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};
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}
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#include "PagedVolume.inl"
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#include "PagedVolumeChunk.inl"
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#include "PagedVolumeSampler.inl"
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#endif //__PolyVox_PagedVolume_H__
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