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126 lines
6.6 KiB
C++
126 lines
6.6 KiB
C++
/*
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This software is provided 'as-is', without any express or implied warranty.
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In no event will the authors be held liable for any damages arising from the use of this software.
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Permission is granted to anyone to use this software for any purpose,
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including commercial applications, and to alter it and redistribute it freely,
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subject to the following restrictions:
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1. The origin of this software must not be misrepresented; you must not claim that you wrote the original software. If you use this software in a product, an acknowledgment in the product documentation would be appreciated but is not required.
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2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software.
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3. This notice may not be removed or altered from any source distribution.
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*/
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//Initial Author Jackson Lee, 2014
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#ifndef B3_GPU_PARALLEL_LINEAR_BVH_H
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#define B3_GPU_PARALLEL_LINEAR_BVH_H
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//#include "Bullet3Collision/BroadPhaseCollision/shared/b3Aabb.h"
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#include "Bullet3OpenCL/BroadphaseCollision/b3SapAabb.h"
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#include "Bullet3Common/shared/b3Int2.h"
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#include "Bullet3Common/shared/b3Int4.h"
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#include "Bullet3Collision/NarrowPhaseCollision/b3RaycastInfo.h"
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#include "Bullet3OpenCL/ParallelPrimitives/b3FillCL.h"
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#include "Bullet3OpenCL/ParallelPrimitives/b3RadixSort32CL.h"
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#include "Bullet3OpenCL/ParallelPrimitives/b3PrefixScanCL.h"
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#include "Bullet3OpenCL/BroadphaseCollision/kernels/parallelLinearBvhKernels.h"
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#define b3Int64 cl_long
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///@brief GPU Parallel Linearized Bounding Volume Heirarchy(LBVH) that is reconstructed every frame
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///@remarks
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///See presentation in docs/b3GpuParallelLinearBvh.pdf for algorithm details.
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///@par
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///Related papers: \n
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///"Fast BVH Construction on GPUs" [Lauterbach et al. 2009] \n
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///"Maximizing Parallelism in the Construction of BVHs, Octrees, and k-d trees" [Karras 2012] \n
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///@par
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///The basic algorithm for building the BVH as presented in [Lauterbach et al. 2009] consists of 4 stages:
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/// - [fully parallel] Assign morton codes for each AABB using its center (after quantizing the AABB centers into a virtual grid)
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/// - [fully parallel] Sort morton codes
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/// - [somewhat parallel] Build binary radix tree (assign parent/child pointers for internal nodes of the BVH)
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/// - [somewhat parallel] Set internal node AABBs
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///@par
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///[Karras 2012] improves on the algorithm by introducing fully parallel methods for the last 2 stages.
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///The BVH implementation here shares many concepts with [Karras 2012], but a different method is used for constructing the tree.
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///Instead of searching for the child nodes of each internal node, we search for the parent node of each node.
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///Additionally, a non-atomic traversal that starts from the leaf nodes and moves towards the root node is used to set the AABBs.
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class b3GpuParallelLinearBvh
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{
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cl_command_queue m_queue;
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cl_program m_parallelLinearBvhProgram;
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cl_kernel m_separateAabbsKernel;
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cl_kernel m_findAllNodesMergedAabbKernel;
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cl_kernel m_assignMortonCodesAndAabbIndiciesKernel;
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//Binary radix tree construction kernels
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cl_kernel m_computeAdjacentPairCommonPrefixKernel;
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cl_kernel m_buildBinaryRadixTreeLeafNodesKernel;
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cl_kernel m_buildBinaryRadixTreeInternalNodesKernel;
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cl_kernel m_findDistanceFromRootKernel;
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cl_kernel m_buildBinaryRadixTreeAabbsRecursiveKernel;
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cl_kernel m_findLeafIndexRangesKernel;
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//Traversal kernels
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cl_kernel m_plbvhCalculateOverlappingPairsKernel;
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cl_kernel m_plbvhRayTraverseKernel;
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cl_kernel m_plbvhLargeAabbAabbTestKernel;
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cl_kernel m_plbvhLargeAabbRayTestKernel;
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b3RadixSort32CL m_radixSorter;
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//1 element
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b3OpenCLArray<int> m_rootNodeIndex; //Most significant bit(0x80000000) is set to indicate internal node
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b3OpenCLArray<int> m_maxDistanceFromRoot; //Max number of internal nodes between an internal node and the root node
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b3OpenCLArray<int> m_temp; //Used to hold the number of pairs in calculateOverlappingPairs()
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//1 element per internal node (number_of_internal_nodes == number_of_leaves - 1)
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b3OpenCLArray<b3SapAabb> m_internalNodeAabbs;
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b3OpenCLArray<b3Int2> m_internalNodeLeafIndexRanges; //x == min leaf index, y == max leaf index
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b3OpenCLArray<b3Int2> m_internalNodeChildNodes; //x == left child, y == right child; msb(0x80000000) is set to indicate internal node
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b3OpenCLArray<int> m_internalNodeParentNodes; //For parent node index, msb(0x80000000) is not set since it is always internal
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//1 element per internal node; for binary radix tree construction
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b3OpenCLArray<b3Int64> m_commonPrefixes;
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b3OpenCLArray<int> m_commonPrefixLengths;
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b3OpenCLArray<int> m_distanceFromRoot; //Number of internal nodes between this node and the root
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//1 element per leaf node (leaf nodes only include small AABBs)
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b3OpenCLArray<int> m_leafNodeParentNodes; //For parent node index, msb(0x80000000) is not set since it is always internal
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b3OpenCLArray<b3SortData> m_mortonCodesAndAabbIndicies; //m_key == morton code, m_value == aabb index in m_leafNodeAabbs
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b3OpenCLArray<b3SapAabb> m_mergedAabb; //m_mergedAabb[0] contains the merged AABB of all leaf nodes
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b3OpenCLArray<b3SapAabb> m_leafNodeAabbs; //Contains only small AABBs
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//1 element per large AABB, which is not stored in the BVH
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b3OpenCLArray<b3SapAabb> m_largeAabbs;
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public:
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b3GpuParallelLinearBvh(cl_context context, cl_device_id device, cl_command_queue queue);
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virtual ~b3GpuParallelLinearBvh();
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///Must be called before any other function
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void build(const b3OpenCLArray<b3SapAabb>& worldSpaceAabbs, const b3OpenCLArray<int>& smallAabbIndices,
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const b3OpenCLArray<int>& largeAabbIndices);
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///calculateOverlappingPairs() uses the worldSpaceAabbs parameter of b3GpuParallelLinearBvh::build() as the query AABBs.
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///@param out_overlappingPairs The size() of this array is used to determine the max number of pairs.
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///If the number of overlapping pairs is < out_overlappingPairs.size(), out_overlappingPairs is resized.
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void calculateOverlappingPairs(b3OpenCLArray<b3Int4>& out_overlappingPairs);
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///@param out_numRigidRayPairs Array of length 1; contains the number of detected ray-rigid AABB intersections;
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///this value may be greater than out_rayRigidPairs.size() if out_rayRigidPairs is not large enough.
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///@param out_rayRigidPairs Contains an array of rays intersecting rigid AABBs; x == ray index, y == rigid body index.
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///If the size of this array is insufficient to hold all ray-rigid AABB intersections, additional intersections are discarded.
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void testRaysAgainstBvhAabbs(const b3OpenCLArray<b3RayInfo>& rays,
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b3OpenCLArray<int>& out_numRayRigidPairs, b3OpenCLArray<b3Int2>& out_rayRigidPairs);
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private:
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void constructBinaryRadixTree();
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};
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#endif
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