diff options
Diffstat (limited to 'thirdparty/embree/kernels/bvh/bvh_rotate.cpp')
| -rw-r--r-- | thirdparty/embree/kernels/bvh/bvh_rotate.cpp | 127 |
1 files changed, 127 insertions, 0 deletions
diff --git a/thirdparty/embree/kernels/bvh/bvh_rotate.cpp b/thirdparty/embree/kernels/bvh/bvh_rotate.cpp new file mode 100644 index 0000000000..460bd60c62 --- /dev/null +++ b/thirdparty/embree/kernels/bvh/bvh_rotate.cpp @@ -0,0 +1,127 @@ +// Copyright 2009-2021 Intel Corporation +// SPDX-License-Identifier: Apache-2.0 + +#include "bvh_rotate.h" + +namespace embree +{ + namespace isa + { + /*! Computes half surface area of box. */ + __forceinline float halfArea3f(const BBox<vfloat4>& box) { + const vfloat4 d = box.size(); + const vfloat4 a = d*shuffle<1,2,0,3>(d); + return a[0]+a[1]+a[2]; + } + + size_t BVHNRotate<4>::rotate(NodeRef parentRef, size_t depth) + { + /*! nothing to rotate if we reached a leaf node. */ + if (parentRef.isBarrier()) return 0; + if (parentRef.isLeaf()) return 0; + AABBNode* parent = parentRef.getAABBNode(); + + /*! rotate all children first */ + vint4 cdepth; + for (size_t c=0; c<4; c++) + cdepth[c] = (int)rotate(parent->child(c),depth+1); + + /* compute current areas of all children */ + vfloat4 sizeX = parent->upper_x-parent->lower_x; + vfloat4 sizeY = parent->upper_y-parent->lower_y; + vfloat4 sizeZ = parent->upper_z-parent->lower_z; + vfloat4 childArea = madd(sizeX,(sizeY + sizeZ),sizeY*sizeZ); + + /*! get node bounds */ + BBox<vfloat4> child1_0,child1_1,child1_2,child1_3; + parent->bounds(child1_0,child1_1,child1_2,child1_3); + + /*! Find best rotation. We pick a first child (child1) and a sub-child + (child2child) of a different second child (child2), and swap child1 + and child2child. We perform the best such swap. */ + float bestArea = 0; + size_t bestChild1 = -1, bestChild2 = -1, bestChild2Child = -1; + for (size_t c2=0; c2<4; c2++) + { + /*! ignore leaf nodes as we cannot descent into them */ + if (parent->child(c2).isBarrier()) continue; + if (parent->child(c2).isLeaf()) continue; + AABBNode* child2 = parent->child(c2).getAABBNode(); + + /*! transpose child bounds */ + BBox<vfloat4> child2c0,child2c1,child2c2,child2c3; + child2->bounds(child2c0,child2c1,child2c2,child2c3); + + /*! put child1_0 at each child2 position */ + float cost00 = halfArea3f(merge(child1_0,child2c1,child2c2,child2c3)); + float cost01 = halfArea3f(merge(child2c0,child1_0,child2c2,child2c3)); + float cost02 = halfArea3f(merge(child2c0,child2c1,child1_0,child2c3)); + float cost03 = halfArea3f(merge(child2c0,child2c1,child2c2,child1_0)); + vfloat4 cost0 = vfloat4(cost00,cost01,cost02,cost03); + vfloat4 min0 = vreduce_min(cost0); + int pos0 = (int)bsf(movemask(min0 == cost0)); + + /*! put child1_1 at each child2 position */ + float cost10 = halfArea3f(merge(child1_1,child2c1,child2c2,child2c3)); + float cost11 = halfArea3f(merge(child2c0,child1_1,child2c2,child2c3)); + float cost12 = halfArea3f(merge(child2c0,child2c1,child1_1,child2c3)); + float cost13 = halfArea3f(merge(child2c0,child2c1,child2c2,child1_1)); + vfloat4 cost1 = vfloat4(cost10,cost11,cost12,cost13); + vfloat4 min1 = vreduce_min(cost1); + int pos1 = (int)bsf(movemask(min1 == cost1)); + + /*! put child1_2 at each child2 position */ + float cost20 = halfArea3f(merge(child1_2,child2c1,child2c2,child2c3)); + float cost21 = halfArea3f(merge(child2c0,child1_2,child2c2,child2c3)); + float cost22 = halfArea3f(merge(child2c0,child2c1,child1_2,child2c3)); + float cost23 = halfArea3f(merge(child2c0,child2c1,child2c2,child1_2)); + vfloat4 cost2 = vfloat4(cost20,cost21,cost22,cost23); + vfloat4 min2 = vreduce_min(cost2); + int pos2 = (int)bsf(movemask(min2 == cost2)); + + /*! put child1_3 at each child2 position */ + float cost30 = halfArea3f(merge(child1_3,child2c1,child2c2,child2c3)); + float cost31 = halfArea3f(merge(child2c0,child1_3,child2c2,child2c3)); + float cost32 = halfArea3f(merge(child2c0,child2c1,child1_3,child2c3)); + float cost33 = halfArea3f(merge(child2c0,child2c1,child2c2,child1_3)); + vfloat4 cost3 = vfloat4(cost30,cost31,cost32,cost33); + vfloat4 min3 = vreduce_min(cost3); + int pos3 = (int)bsf(movemask(min3 == cost3)); + + /*! find best other child */ + vfloat4 area0123 = vfloat4(extract<0>(min0),extract<0>(min1),extract<0>(min2),extract<0>(min3)) - vfloat4(childArea[c2]); + int pos[4] = { pos0,pos1,pos2,pos3 }; + const size_t mbd = BVH4::maxBuildDepth; + vbool4 valid = vint4(int(depth+1))+cdepth <= vint4(mbd); // only select swaps that fulfill depth constraints + valid &= vint4(int(c2)) != vint4(step); + if (none(valid)) continue; + size_t c1 = select_min(valid,area0123); + float area = area0123[c1]; + if (c1 == c2) continue; // can happen if bounds are NANs + + /*! accept a swap when it reduces cost and is not swapping a node with itself */ + if (area < bestArea) { + bestArea = area; + bestChild1 = c1; + bestChild2 = c2; + bestChild2Child = pos[c1]; + } + } + + /*! if we did not find a swap that improves the SAH then do nothing */ + if (bestChild1 == size_t(-1)) return 1+reduce_max(cdepth); + + /*! perform the best found tree rotation */ + AABBNode* child2 = parent->child(bestChild2).getAABBNode(); + AABBNode::swap(parent,bestChild1,child2,bestChild2Child); + parent->setBounds(bestChild2,child2->bounds()); + AABBNode::compact(parent); + AABBNode::compact(child2); + + /*! This returned depth is conservative as the child that was + * pulled up in the tree could have been on the critical path. */ + cdepth[bestChild1]++; // bestChild1 was pushed down one level + return 1+reduce_max(cdepth); + } + } +} |