411 lines
17 KiB
C++
411 lines
17 KiB
C++
// Copyright 2009-2021 Intel Corporation
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// SPDX-License-Identifier: Apache-2.0
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#pragma once
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#include "../bvh/bvh.h"
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#include "../geometry/primitive.h"
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#include "../builders/bvh_builder_sah.h"
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#include "../builders/heuristic_binning_array_aligned.h"
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#include "../builders/heuristic_binning_array_unaligned.h"
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#include "../builders/heuristic_strand_array.h"
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#define NUM_HAIR_OBJECT_BINS 32
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namespace embree
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{
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namespace isa
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{
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struct BVHBuilderHair
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{
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/*! settings for builder */
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struct Settings
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{
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/*! default settings */
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Settings ()
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: branchingFactor(2), maxDepth(32), logBlockSize(0), minLeafSize(1), maxLeafSize(7), finished_range_threshold(inf) {}
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public:
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size_t branchingFactor; //!< branching factor of BVH to build
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size_t maxDepth; //!< maximum depth of BVH to build
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size_t logBlockSize; //!< log2 of blocksize for SAH heuristic
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size_t minLeafSize; //!< minimum size of a leaf
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size_t maxLeafSize; //!< maximum size of a leaf
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size_t finished_range_threshold; //!< finished range threshold
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};
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template<typename NodeRef,
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typename CreateAllocFunc,
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typename CreateAABBNodeFunc,
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typename SetAABBNodeFunc,
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typename CreateOBBNodeFunc,
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typename SetOBBNodeFunc,
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typename CreateLeafFunc,
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typename ProgressMonitor,
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typename ReportFinishedRangeFunc>
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class BuilderT
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{
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ALIGNED_CLASS_(16);
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friend struct BVHBuilderHair;
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typedef FastAllocator::CachedAllocator Allocator;
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typedef HeuristicArrayBinningSAH<PrimRef,NUM_HAIR_OBJECT_BINS> HeuristicBinningSAH;
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typedef UnalignedHeuristicArrayBinningSAH<PrimRef,NUM_HAIR_OBJECT_BINS> UnalignedHeuristicBinningSAH;
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typedef HeuristicStrandSplit HeuristicStrandSplitSAH;
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static const size_t MAX_BRANCHING_FACTOR = 8; //!< maximum supported BVH branching factor
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static const size_t MIN_LARGE_LEAF_LEVELS = 8; //!< create balanced tree if we are that many levels before the maximum tree depth
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static const size_t SINGLE_THREADED_THRESHOLD = 4096; //!< threshold to switch to single threaded build
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static const size_t travCostAligned = 1;
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static const size_t travCostUnaligned = 5;
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static const size_t intCost = 6;
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BuilderT (Scene* scene,
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PrimRef* prims,
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const CreateAllocFunc& createAlloc,
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const CreateAABBNodeFunc& createAABBNode,
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const SetAABBNodeFunc& setAABBNode,
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const CreateOBBNodeFunc& createOBBNode,
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const SetOBBNodeFunc& setOBBNode,
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const CreateLeafFunc& createLeaf,
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const ProgressMonitor& progressMonitor,
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const ReportFinishedRangeFunc& reportFinishedRange,
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const Settings settings)
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: cfg(settings),
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prims(prims),
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createAlloc(createAlloc),
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createAABBNode(createAABBNode),
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setAABBNode(setAABBNode),
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createOBBNode(createOBBNode),
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setOBBNode(setOBBNode),
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createLeaf(createLeaf),
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progressMonitor(progressMonitor),
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reportFinishedRange(reportFinishedRange),
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alignedHeuristic(prims), unalignedHeuristic(scene,prims), strandHeuristic(scene,prims) {}
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/*! checks if all primitives are from the same geometry */
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__forceinline bool sameGeometry(const PrimInfoRange& range)
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{
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if (range.size() == 0) return true;
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unsigned int firstGeomID = prims[range.begin()].geomID();
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for (size_t i=range.begin()+1; i<range.end(); i++) {
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if (prims[i].geomID() != firstGeomID){
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return false;
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}
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}
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return true;
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}
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/*! creates a large leaf that could be larger than supported by the BVH */
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NodeRef createLargeLeaf(size_t depth, const PrimInfoRange& pinfo, Allocator alloc)
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{
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/* this should never occur but is a fatal error */
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if (depth > cfg.maxDepth)
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throw_RTCError(RTC_ERROR_UNKNOWN,"depth limit reached");
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/* create leaf for few primitives */
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if (pinfo.size() <= cfg.maxLeafSize && sameGeometry(pinfo))
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return createLeaf(prims,pinfo,alloc);
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/* fill all children by always splitting the largest one */
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PrimInfoRange children[MAX_BRANCHING_FACTOR];
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unsigned numChildren = 1;
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children[0] = pinfo;
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do {
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/* find best child with largest bounding box area */
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int bestChild = -1;
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size_t bestSize = 0;
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for (unsigned i=0; i<numChildren; i++)
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{
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/* ignore leaves as they cannot get split */
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if (children[i].size() <= cfg.maxLeafSize && sameGeometry(children[i]))
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continue;
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/* remember child with largest size */
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if (children[i].size() > bestSize) {
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bestSize = children[i].size();
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bestChild = i;
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}
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}
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if (bestChild == -1) break;
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/*! split best child into left and right child */
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__aligned(64) PrimInfoRange left, right;
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if (!sameGeometry(children[bestChild])) {
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alignedHeuristic.splitByGeometry(children[bestChild],left,right);
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} else {
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alignedHeuristic.splitFallback(children[bestChild],left,right);
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}
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/* add new children left and right */
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children[bestChild] = children[numChildren-1];
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children[numChildren-1] = left;
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children[numChildren+0] = right;
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numChildren++;
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} while (numChildren < cfg.branchingFactor);
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/* create node */
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auto node = createAABBNode(alloc);
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for (size_t i=0; i<numChildren; i++) {
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const NodeRef child = createLargeLeaf(depth+1,children[i],alloc);
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setAABBNode(node,i,child,children[i].geomBounds);
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}
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return node;
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}
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/*! performs split */
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__noinline void split(const PrimInfoRange& pinfo, PrimInfoRange& linfo, PrimInfoRange& rinfo, bool& aligned) // FIXME: not inlined as ICC otherwise uses much stack
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{
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/* variable to track the SAH of the best splitting approach */
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float bestSAH = inf;
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const size_t blocks = (pinfo.size()+(1ull<<cfg.logBlockSize)-1ull) >> cfg.logBlockSize;
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const float leafSAH = intCost*float(blocks)*halfArea(pinfo.geomBounds);
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/* try standard binning in aligned space */
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float alignedObjectSAH = inf;
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HeuristicBinningSAH::Split alignedObjectSplit;
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if (aligned) {
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alignedObjectSplit = alignedHeuristic.find(pinfo,cfg.logBlockSize);
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alignedObjectSAH = travCostAligned*halfArea(pinfo.geomBounds) + intCost*alignedObjectSplit.splitSAH();
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bestSAH = min(alignedObjectSAH,bestSAH);
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}
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/* try standard binning in unaligned space */
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UnalignedHeuristicBinningSAH::Split unalignedObjectSplit;
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LinearSpace3fa uspace;
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float unalignedObjectSAH = inf;
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if (bestSAH > 0.7f*leafSAH) {
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uspace = unalignedHeuristic.computeAlignedSpace(pinfo);
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const PrimInfoRange sinfo = unalignedHeuristic.computePrimInfo(pinfo,uspace);
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unalignedObjectSplit = unalignedHeuristic.find(sinfo,cfg.logBlockSize,uspace);
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unalignedObjectSAH = travCostUnaligned*halfArea(pinfo.geomBounds) + intCost*unalignedObjectSplit.splitSAH();
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bestSAH = min(unalignedObjectSAH,bestSAH);
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}
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/* try splitting into two strands */
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HeuristicStrandSplitSAH::Split strandSplit;
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float strandSAH = inf;
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if (bestSAH > 0.7f*leafSAH && pinfo.size() <= 256) {
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strandSplit = strandHeuristic.find(pinfo,cfg.logBlockSize);
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strandSAH = travCostUnaligned*halfArea(pinfo.geomBounds) + intCost*strandSplit.splitSAH();
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bestSAH = min(strandSAH,bestSAH);
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}
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/* fallback if SAH heuristics failed */
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if (unlikely(!std::isfinite(bestSAH)))
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{
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alignedHeuristic.deterministic_order(pinfo);
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alignedHeuristic.splitFallback(pinfo,linfo,rinfo);
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}
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/* perform aligned split if this is best */
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else if (bestSAH == alignedObjectSAH) {
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alignedHeuristic.split(alignedObjectSplit,pinfo,linfo,rinfo);
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}
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/* perform unaligned split if this is best */
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else if (bestSAH == unalignedObjectSAH) {
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unalignedHeuristic.split(unalignedObjectSplit,uspace,pinfo,linfo,rinfo);
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aligned = false;
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}
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/* perform strand split if this is best */
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else if (bestSAH == strandSAH) {
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strandHeuristic.split(strandSplit,pinfo,linfo,rinfo);
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aligned = false;
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}
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/* can never happen */
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else
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assert(false);
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}
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/*! recursive build */
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NodeRef recurse(size_t depth, const PrimInfoRange& pinfo, Allocator alloc, bool toplevel, bool alloc_barrier)
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{
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/* get thread local allocator */
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if (!alloc)
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alloc = createAlloc();
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/* call memory monitor function to signal progress */
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if (toplevel && pinfo.size() <= SINGLE_THREADED_THRESHOLD)
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progressMonitor(pinfo.size());
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PrimInfoRange children[MAX_BRANCHING_FACTOR];
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/* create leaf node */
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if (depth+MIN_LARGE_LEAF_LEVELS >= cfg.maxDepth || pinfo.size() <= cfg.minLeafSize) {
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alignedHeuristic.deterministic_order(pinfo);
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return createLargeLeaf(depth,pinfo,alloc);
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}
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/* fill all children by always splitting the one with the largest surface area */
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size_t numChildren = 1;
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children[0] = pinfo;
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bool aligned = true;
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do {
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/* find best child with largest bounding box area */
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ssize_t bestChild = -1;
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float bestArea = neg_inf;
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for (size_t i=0; i<numChildren; i++)
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{
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/* ignore leaves as they cannot get split */
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if (children[i].size() <= cfg.minLeafSize)
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continue;
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/* remember child with largest area */
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if (area(children[i].geomBounds) > bestArea) {
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bestArea = area(children[i].geomBounds);
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bestChild = i;
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}
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}
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if (bestChild == -1) break;
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/*! split best child into left and right child */
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PrimInfoRange left, right;
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split(children[bestChild],left,right,aligned);
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/* add new children left and right */
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children[bestChild] = children[numChildren-1];
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children[numChildren-1] = left;
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children[numChildren+0] = right;
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numChildren++;
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} while (numChildren < cfg.branchingFactor);
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NodeRef node;
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/* create aligned node */
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if (aligned)
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{
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node = createAABBNode(alloc);
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/* spawn tasks or ... */
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if (pinfo.size() > SINGLE_THREADED_THRESHOLD)
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{
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parallel_for(size_t(0), numChildren, [&] (const range<size_t>& r) {
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for (size_t i=r.begin(); i<r.end(); i++) {
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const bool child_alloc_barrier = pinfo.size() > cfg.finished_range_threshold && children[i].size() <= cfg.finished_range_threshold;
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setAABBNode(node,i,recurse(depth+1,children[i],nullptr,true,child_alloc_barrier),children[i].geomBounds);
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_mm_mfence(); // to allow non-temporal stores during build
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}
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});
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}
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/* ... continue sequentially */
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else {
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for (size_t i=0; i<numChildren; i++) {
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const bool child_alloc_barrier = pinfo.size() > cfg.finished_range_threshold && children[i].size() <= cfg.finished_range_threshold;
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setAABBNode(node,i,recurse(depth+1,children[i],alloc,false,child_alloc_barrier),children[i].geomBounds);
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}
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}
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}
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/* create unaligned node */
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else
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{
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node = createOBBNode(alloc);
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/* spawn tasks or ... */
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if (pinfo.size() > SINGLE_THREADED_THRESHOLD)
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{
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parallel_for(size_t(0), numChildren, [&] (const range<size_t>& r) {
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for (size_t i=r.begin(); i<r.end(); i++) {
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const LinearSpace3fa space = unalignedHeuristic.computeAlignedSpace(children[i]);
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const PrimInfoRange sinfo = unalignedHeuristic.computePrimInfo(children[i],space);
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const OBBox3fa obounds(space,sinfo.geomBounds);
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const bool child_alloc_barrier = pinfo.size() > cfg.finished_range_threshold && children[i].size() <= cfg.finished_range_threshold;
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setOBBNode(node,i,recurse(depth+1,children[i],nullptr,true,child_alloc_barrier),obounds);
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_mm_mfence(); // to allow non-temporal stores during build
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}
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});
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}
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/* ... continue sequentially */
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else
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{
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for (size_t i=0; i<numChildren; i++) {
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const LinearSpace3fa space = unalignedHeuristic.computeAlignedSpace(children[i]);
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const PrimInfoRange sinfo = unalignedHeuristic.computePrimInfo(children[i],space);
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const OBBox3fa obounds(space,sinfo.geomBounds);
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const bool child_alloc_barrier = pinfo.size() > cfg.finished_range_threshold && children[i].size() <= cfg.finished_range_threshold;
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setOBBNode(node,i,recurse(depth+1,children[i],alloc,false,child_alloc_barrier),obounds);
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}
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}
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}
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/* reports a finished range of primrefs */
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if (unlikely(alloc_barrier))
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reportFinishedRange(pinfo);
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return node;
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}
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private:
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Settings cfg;
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PrimRef* prims;
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const CreateAllocFunc& createAlloc;
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const CreateAABBNodeFunc& createAABBNode;
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const SetAABBNodeFunc& setAABBNode;
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const CreateOBBNodeFunc& createOBBNode;
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const SetOBBNodeFunc& setOBBNode;
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const CreateLeafFunc& createLeaf;
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const ProgressMonitor& progressMonitor;
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const ReportFinishedRangeFunc& reportFinishedRange;
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private:
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HeuristicBinningSAH alignedHeuristic;
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UnalignedHeuristicBinningSAH unalignedHeuristic;
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HeuristicStrandSplitSAH strandHeuristic;
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};
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template<typename NodeRef,
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typename CreateAllocFunc,
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typename CreateAABBNodeFunc,
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typename SetAABBNodeFunc,
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typename CreateOBBNodeFunc,
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typename SetOBBNodeFunc,
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typename CreateLeafFunc,
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typename ProgressMonitor,
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typename ReportFinishedRangeFunc>
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static NodeRef build (const CreateAllocFunc& createAlloc,
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const CreateAABBNodeFunc& createAABBNode,
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const SetAABBNodeFunc& setAABBNode,
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const CreateOBBNodeFunc& createOBBNode,
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const SetOBBNodeFunc& setOBBNode,
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const CreateLeafFunc& createLeaf,
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const ProgressMonitor& progressMonitor,
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const ReportFinishedRangeFunc& reportFinishedRange,
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Scene* scene,
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PrimRef* prims,
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const PrimInfo& pinfo,
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const Settings settings)
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{
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typedef BuilderT<NodeRef,
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CreateAllocFunc,
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CreateAABBNodeFunc,SetAABBNodeFunc,
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CreateOBBNodeFunc,SetOBBNodeFunc,
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CreateLeafFunc,ProgressMonitor,
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ReportFinishedRangeFunc> Builder;
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Builder builder(scene,prims,createAlloc,
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createAABBNode,setAABBNode,
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createOBBNode,setOBBNode,
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createLeaf,progressMonitor,reportFinishedRange,settings);
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NodeRef root = builder.recurse(1,pinfo,nullptr,true,false);
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_mm_mfence(); // to allow non-temporal stores during build
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return root;
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}
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};
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}
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}
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