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++ // Copyright 2009-2021 Intel Corporation
++ // SPDX-License-Identifier: Apache-2.0
++
++ // TODO:
++ // - adjust parallel build thresholds
++ // - openNodesBasedOnExtend should consider max extended size
++
++ #pragma once
++
++ #include "heuristic_binning.h"
++ #include "heuristic_spatial.h"
++
++ /* stop opening of all bref.geomIDs are the same */
++ #define EQUAL_GEOMID_STOP_CRITERIA 1
++
++ /* 10% spatial extend threshold */
++ #define MAX_EXTEND_THRESHOLD 0.1f
++
++ /* maximum is 8 children */
++ #define MAX_OPENED_CHILD_NODES 8
++
++ /* open until all build refs are below threshold size in one step */
++ #define USE_LOOP_OPENING 0
++
++ namespace embree
++ {
++ namespace isa
++ {
++ /*! Performs standard object binning */
++ template<typename NodeOpenerFunc, typename PrimRef, size_t OBJECT_BINS>
++ struct HeuristicArrayOpenMergeSAH
++ {
++ typedef BinSplit<OBJECT_BINS> Split;
++ typedef BinInfoT<OBJECT_BINS,PrimRef,BBox3fa> Binner;
++
++ static const size_t PARALLEL_THRESHOLD = 1024;
++ static const size_t PARALLEL_FIND_BLOCK_SIZE = 512;
++ static const size_t PARALLEL_PARTITION_BLOCK_SIZE = 128;
++
++ static const size_t MOVE_STEP_SIZE = 64;
++ static const size_t CREATE_SPLITS_STEP_SIZE = 128;
++
++ __forceinline HeuristicArrayOpenMergeSAH ()
++ : prims0(nullptr) {}
++
++ /*! remember prim array */
++ __forceinline HeuristicArrayOpenMergeSAH (const NodeOpenerFunc& nodeOpenerFunc, PrimRef* prims0, size_t max_open_size)
++ : prims0(prims0), nodeOpenerFunc(nodeOpenerFunc), max_open_size(max_open_size)
++ {
++ assert(max_open_size <= MAX_OPENED_CHILD_NODES);
++ }
++
++ struct OpenHeuristic
++ {
++ __forceinline OpenHeuristic( const PrimInfoExtRange& pinfo )
++ {
++ const Vec3fa diag = pinfo.geomBounds.size();
++ dim = maxDim(diag);
++ assert(diag[dim] > 0.0f);
++ inv_max_extend = 1.0f / diag[dim];
++ }
++
++ __forceinline bool operator () ( PrimRef& prim ) const {
++ return !prim.node.isLeaf() && prim.bounds().size()[dim] * inv_max_extend > MAX_EXTEND_THRESHOLD;
++ }
++
++ private:
++ size_t dim;
++ float inv_max_extend;
++ };
++
++ /*! compute extended ranges */
++ __forceinline void setExtentedRanges(const PrimInfoExtRange& set, PrimInfoExtRange& lset, PrimInfoExtRange& rset, const size_t lweight, const size_t rweight)
++ {
++ assert(set.ext_range_size() > 0);
++ const float left_factor = (float)lweight / (lweight + rweight);
++ const size_t ext_range_size = set.ext_range_size();
++ const size_t left_ext_range_size = min((size_t)(floorf(left_factor * ext_range_size)),ext_range_size);
++ const size_t right_ext_range_size = ext_range_size - left_ext_range_size;
++ lset.set_ext_range(lset.end() + left_ext_range_size);
++ rset.set_ext_range(rset.end() + right_ext_range_size);
++ }
++
++ /*! move ranges */
++ __forceinline void moveExtentedRange(const PrimInfoExtRange& set, const PrimInfoExtRange& lset, PrimInfoExtRange& rset)
++ {
++ const size_t left_ext_range_size = lset.ext_range_size();
++ const size_t right_size = rset.size();
++
++ /* has the left child an extended range? */
++ if (left_ext_range_size > 0)
++ {
++ /* left extended range smaller than right range ? */
++ if (left_ext_range_size < right_size)
++ {
++ /* only move a small part of the beginning of the right range to the end */
++ parallel_for( rset.begin(), rset.begin()+left_ext_range_size, MOVE_STEP_SIZE, [&](const range<size_t>& r) {
++ for (size_t i=r.begin(); i<r.end(); i++)
++ prims0[i+right_size] = prims0[i];
++ });
++ }
++ else
++ {
++ /* no overlap, move entire right range to new location, can be made fully parallel */
++ parallel_for( rset.begin(), rset.end(), MOVE_STEP_SIZE, [&](const range<size_t>& r) {
++ for (size_t i=r.begin(); i<r.end(); i++)
++ prims0[i+left_ext_range_size] = prims0[i];
++ });
++ }
++ /* update right range */
++ assert(rset.ext_end() + left_ext_range_size == set.ext_end());
++ rset.move_right(left_ext_range_size);
++ }
++ }
++
++ /* estimates the extra space required when opening, and checks if all primitives are from same geometry */
++ __noinline std::pair<size_t,bool> getProperties(const PrimInfoExtRange& set)
++ {
++ const OpenHeuristic heuristic(set);
++ const unsigned int geomID = prims0[set.begin()].geomID();
++
++ auto body = [&] (const range<size_t>& r) -> std::pair<size_t,bool> {
++ bool commonGeomID = true;
++ size_t opens = 0;
++ for (size_t i=r.begin(); i<r.end(); i++) {
++ commonGeomID &= prims0[i].geomID() == geomID;
++ if (heuristic(prims0[i]))
++ opens += prims0[i].node.getN()-1; // coarse approximation
++ }
++ return std::pair<size_t,bool>(opens,commonGeomID);
++ };
++ auto reduction = [&] (const std::pair<size_t,bool>& b0, const std::pair<size_t,bool>& b1) -> std::pair<size_t,bool> {
++ return std::pair<size_t,bool>(b0.first+b1.first,b0.second && b1.second);
++ };
++ return parallel_reduce(set.begin(),set.end(),PARALLEL_FIND_BLOCK_SIZE,PARALLEL_THRESHOLD,std::pair<size_t,bool>(0,true),body,reduction);
++ }
++
++ // FIXME: should consider maximum available extended size
++ __noinline void openNodesBasedOnExtend(PrimInfoExtRange& set)
++ {
++ const OpenHeuristic heuristic(set);
++ const size_t ext_range_start = set.end();
++
++ if (false && set.size() < PARALLEL_THRESHOLD)
++ {
++ size_t extra_elements = 0;
++ for (size_t i=set.begin(); i<set.end(); i++)
++ {
++ if (heuristic(prims0[i]))
++ {
++ PrimRef tmp[MAX_OPENED_CHILD_NODES];
++ const size_t n = nodeOpenerFunc(prims0[i],tmp);
++ assert(extra_elements + n-1 <= set.ext_range_size());
++ for (size_t j=0; j<n; j++)
++ set.extend_center2(tmp[j]);
++
++ prims0[i] = tmp[0];
++ for (size_t j=1; j<n; j++)
++ prims0[ext_range_start+extra_elements+j-1] = tmp[j];
++ extra_elements += n-1;
++ }
++ }
++ set._end += extra_elements;
++ }
++ else
++ {
++ std::atomic<size_t> ext_elements;
++ ext_elements.store(0);
++ PrimInfo info = parallel_reduce( set.begin(), set.end(), CREATE_SPLITS_STEP_SIZE, PrimInfo(empty), [&](const range<size_t>& r) -> PrimInfo {
++ PrimInfo info(empty);
++ for (size_t i=r.begin(); i<r.end(); i++)
++ if (heuristic(prims0[i]))
++ {
++ PrimRef tmp[MAX_OPENED_CHILD_NODES];
++ const size_t n = nodeOpenerFunc(prims0[i],tmp);
++ const size_t ID = ext_elements.fetch_add(n-1);
++ assert(ID + n-1 <= set.ext_range_size());
++
++ for (size_t j=0; j<n; j++)
++ info.extend_center2(tmp[j]);
++
++ prims0[i] = tmp[0];
++ for (size_t j=1; j<n; j++)
++ prims0[ext_range_start+ID+j-1] = tmp[j];
++ }
++ return info;
++ }, [] (const PrimInfo& a, const PrimInfo& b) { return PrimInfo::merge(a,b); });
++ set.centBounds.extend(info.centBounds);
++ assert(ext_elements.load() <= set.ext_range_size());
++ set._end += ext_elements.load();
++ }
++ }
++
++ __noinline void openNodesBasedOnExtendLoop(PrimInfoExtRange& set, const size_t est_new_elements)
++ {
++ const OpenHeuristic heuristic(set);
++ size_t next_iteration_extra_elements = est_new_elements;
++
++ while (next_iteration_extra_elements <= set.ext_range_size())
++ {
++ next_iteration_extra_elements = 0;
++ size_t extra_elements = 0;
++ const size_t ext_range_start = set.end();
++
++ for (size_t i=set.begin(); i<set.end(); i++)
++ {
++ if (heuristic(prims0[i]))
++ {
++ PrimRef tmp[MAX_OPENED_CHILD_NODES];
++ const size_t n = nodeOpenerFunc(prims0[i],tmp);
++ assert(extra_elements + n-1 <= set.ext_range_size());
++ for (size_t j=0;j<n;j++)
++ set.extend_center2(tmp[j]);
++
++ prims0[i] = tmp[0];
++ for (size_t j=1;j<n;j++)
++ prims0[ext_range_start+extra_elements+j-1] = tmp[j];
++ extra_elements += n-1;
++
++ for (size_t j=0; j<n; j++)
++ if (heuristic(tmp[j]))
++ next_iteration_extra_elements += tmp[j].node.getN()-1; // coarse approximation
++
++ }
++ }
++ assert( extra_elements <= set.ext_range_size());
++ set._end += extra_elements;
++
++ for (size_t i=set.begin();i<set.end();i++)
++ assert(prims0[i].numPrimitives() > 0);
++
++ if (unlikely(next_iteration_extra_elements == 0)) break;
++ }
++ }
++
++ __noinline const Split find(PrimInfoExtRange& set, const size_t logBlockSize)
++ {
++ /* single element */
++ if (set.size() <= 1)
++ return Split();
++
++ /* disable opening if there is no overlap */
++ const size_t D = 4;
++ if (unlikely(set.has_ext_range() && set.size() <= D))
++ {
++ bool disjoint = true;
++ for (size_t j=set.begin(); j<set.end()-1; j++) {
++ for (size_t i=set.begin()+1; i<set.end(); i++) {
++ if (conjoint(prims0[j].bounds(),prims0[i].bounds())) {
++ disjoint = false; break;
++ }
++ }
++ }
++ if (disjoint) set.set_ext_range(set.end()); /* disables opening */
++ }
++
++ std::pair<size_t,bool> p(0,false);
++
++ /* disable opening when all primitives are from same geometry */
++ if (unlikely(set.has_ext_range()))
++ {
++ p = getProperties(set);
++ #if EQUAL_GEOMID_STOP_CRITERIA == 1
++ if (p.second) set.set_ext_range(set.end()); /* disable opening */
++ #endif
++ }
++
++ /* open nodes when we have sufficient space available */
++ if (unlikely(set.has_ext_range()))
++ {
++ #if USE_LOOP_OPENING == 1
++ openNodesBasedOnExtendLoop(set,p.first);
++ #else
++ if (p.first <= set.ext_range_size())
++ openNodesBasedOnExtend(set);
++ #endif
++
++ /* disable opening when unsufficient space for opening a node available */
++ if (set.ext_range_size() < max_open_size-1)
++ set.set_ext_range(set.end()); /* disable opening */
++ }
++
++ /* find best split */
++ return object_find(set,logBlockSize);
++ }
++
++
++ /*! finds the best object split */
++ __forceinline const Split object_find(const PrimInfoExtRange& set,const size_t logBlockSize)
++ {
++ if (set.size() < PARALLEL_THRESHOLD) return sequential_object_find(set,logBlockSize);
++ else return parallel_object_find (set,logBlockSize);
++ }
++
++ /*! finds the best object split */
++ __noinline const Split sequential_object_find(const PrimInfoExtRange& set, const size_t logBlockSize)
++ {
++ Binner binner(empty);
++ const BinMapping<OBJECT_BINS> mapping(set.centBounds);
++ binner.bin(prims0,set.begin(),set.end(),mapping);
++ return binner.best(mapping,logBlockSize);
++ }
++
++ /*! finds the best split */
++ __noinline const Split parallel_object_find(const PrimInfoExtRange& set, const size_t logBlockSize)
++ {
++ Binner binner(empty);
++ const BinMapping<OBJECT_BINS> mapping(set.centBounds);
++ const BinMapping<OBJECT_BINS>& _mapping = mapping; // CLANG 3.4 parser bug workaround
++ auto body = [&] (const range<size_t>& r) -> Binner {
++ Binner binner(empty); binner.bin(prims0+r.begin(),r.size(),_mapping); return binner;
++ };
++ auto reduction = [&] (const Binner& b0, const Binner& b1) -> Binner {
++ Binner r = b0; r.merge(b1,_mapping.size()); return r;
++ };
++ binner = parallel_reduce(set.begin(),set.end(),PARALLEL_FIND_BLOCK_SIZE,binner,body,reduction);
++ return binner.best(mapping,logBlockSize);
++ }
++
++ /*! array partitioning */
++ __noinline void split(const Split& split, const PrimInfoExtRange& set_i, PrimInfoExtRange& lset, PrimInfoExtRange& rset)
++ {
++ PrimInfoExtRange set = set_i;
++
++ /* valid split */
++ if (unlikely(!split.valid())) {
++ deterministic_order(set);
++ splitFallback(set,lset,rset);
++ return;
++ }
++
++ std::pair<size_t,size_t> ext_weights(0,0);
++
++ /* object split */
++ if (likely(set.size() < PARALLEL_THRESHOLD))
++ ext_weights = sequential_object_split(split,set,lset,rset);
++ else
++ ext_weights = parallel_object_split(split,set,lset,rset);
++
++ /* if we have an extended range, set extended child ranges and move right split range */
++ if (unlikely(set.has_ext_range()))
++ {
++ setExtentedRanges(set,lset,rset,ext_weights.first,ext_weights.second);
++ moveExtentedRange(set,lset,rset);
++ }
++ }
++
++ /*! array partitioning */
++ std::pair<size_t,size_t> sequential_object_split(const Split& split, const PrimInfoExtRange& set, PrimInfoExtRange& lset, PrimInfoExtRange& rset)
++ {
++ const size_t begin = set.begin();
++ const size_t end = set.end();
++ PrimInfo local_left(empty);
++ PrimInfo local_right(empty);
++ const unsigned int splitPos = split.pos;
++ const unsigned int splitDim = split.dim;
++ const unsigned int splitDimMask = (unsigned int)1 << splitDim;
++
++ const vint4 vSplitPos(splitPos);
++ const vbool4 vSplitMask( (int)splitDimMask );
++
++ size_t center = serial_partitioning(prims0,
++ begin,end,local_left,local_right,
++ [&] (const PrimRef& ref) { return split.mapping.bin_unsafe(ref,vSplitPos,vSplitMask); },
++ [] (PrimInfo& pinfo,const PrimRef& ref) { pinfo.add_center2(ref); });
++
++ new (&lset) PrimInfoExtRange(begin,center,center,local_left);
++ new (&rset) PrimInfoExtRange(center,end,end,local_right);
++ assert(area(lset.geomBounds) >= 0.0f);
++ assert(area(rset.geomBounds) >= 0.0f);
++ return std::pair<size_t,size_t>(local_left.size(),local_right.size());
++ }
++
++ /*! array partitioning */
++ __noinline std::pair<size_t,size_t> parallel_object_split(const Split& split, const PrimInfoExtRange& set, PrimInfoExtRange& lset, PrimInfoExtRange& rset)
++ {
++ const size_t begin = set.begin();
++ const size_t end = set.end();
++ PrimInfo left(empty);
++ PrimInfo right(empty);
++ const unsigned int splitPos = split.pos;
++ const unsigned int splitDim = split.dim;
++ const unsigned int splitDimMask = (unsigned int)1 << splitDim;
++
++ const vint4 vSplitPos(splitPos);
++ const vbool4 vSplitMask( (int)splitDimMask );
++ auto isLeft = [&] (const PrimRef& ref) { return split.mapping.bin_unsafe(ref,vSplitPos,vSplitMask); };
++
++ const size_t center = parallel_partitioning(
++ prims0,begin,end,EmptyTy(),left,right,isLeft,
++ [] (PrimInfo& pinfo,const PrimRef& ref) { pinfo.add_center2(ref); },
++ [] (PrimInfo& pinfo0,const PrimInfo& pinfo1) { pinfo0.merge(pinfo1); },
++ PARALLEL_PARTITION_BLOCK_SIZE);
++
++ new (&lset) PrimInfoExtRange(begin,center,center,left);
++ new (&rset) PrimInfoExtRange(center,end,end,right);
++ assert(area(lset.geomBounds) >= 0.0f);
++ assert(area(rset.geomBounds) >= 0.0f);
++
++ return std::pair<size_t,size_t>(left.size(),right.size());
++ }
++
++ void deterministic_order(const extended_range<size_t>& set)
++ {
++ /* required as parallel partition destroys original primitive order */
++ std::sort(&prims0[set.begin()],&prims0[set.end()]);
++ }
++
++ __forceinline void splitFallback(const PrimInfoExtRange& set, PrimInfoExtRange& lset, PrimInfoExtRange& rset)
++ {
++ const size_t begin = set.begin();
++ const size_t end = set.end();
++ const size_t center = (begin + end)/2;
++
++ PrimInfo left(empty);
++ for (size_t i=begin; i<center; i++)
++ left.add_center2(prims0[i]);
++
++ const size_t lweight = left.end;
++
++ PrimInfo right(empty);
++ for (size_t i=center; i<end; i++)
++ right.add_center2(prims0[i]);
++
++ const size_t rweight = right.end;
++ new (&lset) PrimInfoExtRange(begin,center,center,left);
++ new (&rset) PrimInfoExtRange(center,end,end,right);
++
++ /* if we have an extended range */
++ if (set.has_ext_range())
++ {
++ setExtentedRanges(set,lset,rset,lweight,rweight);
++ moveExtentedRange(set,lset,rset);
++ }
++ }
++
++ private:
++ PrimRef* const prims0;
++ const NodeOpenerFunc& nodeOpenerFunc;
++ size_t max_open_size;
++ };
++ }
++ }