initial commit, 4.5 stable

thirdparty/embree/kernels/builders/bvh_builder_hair.h

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