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367 lines
14 KiB
C++
367 lines
14 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 "../common/scene.h"
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#include "priminfo.h"
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namespace embree
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{
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static const unsigned int RESERVED_NUM_SPATIAL_SPLITS_GEOMID_BITS = 5;
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namespace isa
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{
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/*! mapping into bins */
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template<size_t BINS>
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struct SpatialBinMapping
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{
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public:
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__forceinline SpatialBinMapping() {}
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/*! calculates the mapping */
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__forceinline SpatialBinMapping(const CentGeomBBox3fa& pinfo)
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{
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const vfloat4 lower = (vfloat4) pinfo.geomBounds.lower;
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const vfloat4 upper = (vfloat4) pinfo.geomBounds.upper;
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const vfloat4 eps = 128.0f*vfloat4(ulp)*max(abs(lower),abs(upper));
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const vfloat4 diag = max(eps,(vfloat4) pinfo.geomBounds.size());
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scale = select(upper-lower <= eps,vfloat4(0.0f),vfloat4(BINS)/diag);
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ofs = (vfloat4) pinfo.geomBounds.lower;
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inv_scale = 1.0f / scale;
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}
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/*! slower but safe binning */
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__forceinline vint4 bin(const Vec3fa& p) const
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{
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const vint4 i = floori((vfloat4(p)-ofs)*scale);
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return clamp(i,vint4(0),vint4(BINS-1));
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}
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__forceinline std::pair<vint4,vint4> bin(const BBox3fa& b) const
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{
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#if defined(__AVX__)
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const vfloat8 ofs8(ofs);
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const vfloat8 scale8(scale);
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const vint8 lu = floori((vfloat8::loadu(&b)-ofs8)*scale8);
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const vint8 c_lu = clamp(lu,vint8(zero),vint8(BINS-1));
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return std::pair<vint4,vint4>(extract4<0>(c_lu),extract4<1>(c_lu));
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#else
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const vint4 lower = floori((vfloat4(b.lower)-ofs)*scale);
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const vint4 upper = floori((vfloat4(b.upper)-ofs)*scale);
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const vint4 c_lower = clamp(lower,vint4(0),vint4(BINS-1));
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const vint4 c_upper = clamp(upper,vint4(0),vint4(BINS-1));
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return std::pair<vint4,vint4>(c_lower,c_upper);
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#endif
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}
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/*! calculates left spatial position of bin */
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__forceinline float pos(const size_t bin, const size_t dim) const {
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return madd(float(bin),inv_scale[dim],ofs[dim]);
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}
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/*! calculates left spatial position of bin */
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template<size_t N>
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__forceinline vfloat<N> posN(const vfloat<N> bin, const size_t dim) const {
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return madd(bin,vfloat<N>(inv_scale[dim]),vfloat<N>(ofs[dim]));
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}
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/*! returns true if the mapping is invalid in some dimension */
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__forceinline bool invalid(const size_t dim) const {
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return scale[dim] == 0.0f;
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}
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public:
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vfloat4 ofs,scale,inv_scale; //!< linear function that maps to bin ID
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};
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/*! stores all information required to perform some split */
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template<size_t BINS>
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struct SpatialBinSplit
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{
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/*! construct an invalid split by default */
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__forceinline SpatialBinSplit()
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: sah(inf), dim(-1), pos(0), left(-1), right(-1), factor(1.0f) {}
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/*! constructs specified split */
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__forceinline SpatialBinSplit(float sah, int dim, int pos, const SpatialBinMapping<BINS>& mapping)
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: sah(sah), dim(dim), pos(pos), left(-1), right(-1), factor(1.0f), mapping(mapping) {}
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/*! constructs specified split */
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__forceinline SpatialBinSplit(float sah, int dim, int pos, int left, int right, float factor, const SpatialBinMapping<BINS>& mapping)
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: sah(sah), dim(dim), pos(pos), left(left), right(right), factor(factor), mapping(mapping) {}
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/*! tests if this split is valid */
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__forceinline bool valid() const { return dim != -1; }
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/*! calculates surface area heuristic for performing the split */
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__forceinline float splitSAH() const { return sah; }
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/*! stream output */
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friend embree_ostream operator<<(embree_ostream cout, const SpatialBinSplit& split) {
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return cout << "SpatialBinSplit { sah = " << split.sah << ", dim = " << split.dim << ", pos = " << split.pos << ", left = " << split.left << ", right = " << split.right << ", factor = " << split.factor << "}";
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}
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public:
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float sah; //!< SAH cost of the split
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int dim; //!< split dimension
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int pos; //!< split position
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int left; //!< number of elements on the left side
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int right; //!< number of elements on the right side
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float factor; //!< factor splitting the extended range
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SpatialBinMapping<BINS> mapping; //!< mapping into bins
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};
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/*! stores all binning information */
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template<size_t BINS, typename PrimRef>
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struct __aligned(64) SpatialBinInfo
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{
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SpatialBinInfo() {
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}
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__forceinline SpatialBinInfo(EmptyTy) {
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clear();
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}
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/*! clears the bin info */
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__forceinline void clear()
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{
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for (size_t i=0; i<BINS; i++) {
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bounds[i][0] = bounds[i][1] = bounds[i][2] = empty;
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numBegin[i] = numEnd[i] = 0;
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}
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}
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/*! adds binning data */
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__forceinline void add(const size_t dim,
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const size_t beginID,
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const size_t endID,
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const size_t binID,
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const BBox3fa &b,
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const size_t n = 1)
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{
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assert(beginID < BINS);
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assert(endID < BINS);
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assert(binID < BINS);
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numBegin[beginID][dim]+=(unsigned int)n;
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numEnd [endID][dim]+=(unsigned int)n;
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bounds [binID][dim].extend(b);
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}
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/*! extends binning bounds */
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__forceinline void extend(const size_t dim,
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const size_t binID,
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const BBox3fa &b)
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{
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assert(binID < BINS);
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bounds [binID][dim].extend(b);
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}
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/*! bins an array of primitives */
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template<typename PrimitiveSplitterFactory>
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__forceinline void bin2(const PrimitiveSplitterFactory& splitterFactory, const PrimRef* source, size_t begin, size_t end, const SpatialBinMapping<BINS>& mapping)
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{
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for (size_t i=begin; i<end; i++)
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{
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const PrimRef& prim = source[i];
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unsigned splits = prim.geomID() >> (32-RESERVED_NUM_SPATIAL_SPLITS_GEOMID_BITS);
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if (unlikely(splits <= 1))
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{
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const vint4 bin = mapping.bin(center(prim.bounds()));
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for (size_t dim=0; dim<3; dim++)
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{
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assert(bin[dim] >= (int)0 && bin[dim] < (int)BINS);
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add(dim,bin[dim],bin[dim],bin[dim],prim.bounds());
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}
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}
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else
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{
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const vint4 bin0 = mapping.bin(prim.bounds().lower);
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const vint4 bin1 = mapping.bin(prim.bounds().upper);
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for (size_t dim=0; dim<3; dim++)
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{
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if (unlikely(mapping.invalid(dim)))
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continue;
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size_t bin;
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size_t l = bin0[dim];
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size_t r = bin1[dim];
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// same bin optimization
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if (likely(l == r))
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{
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add(dim,l,l,l,prim.bounds());
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continue;
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}
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size_t bin_start = bin0[dim];
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size_t bin_end = bin1[dim];
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BBox3fa rest = prim.bounds();
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/* assure that split position always overlaps the primitive bounds */
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while (bin_start < bin_end && mapping.pos(bin_start+1,dim) <= rest.lower[dim]) bin_start++;
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while (bin_start < bin_end && mapping.pos(bin_end ,dim) >= rest.upper[dim]) bin_end--;
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const auto splitter = splitterFactory(prim);
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for (bin=bin_start; bin<bin_end; bin++)
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{
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const float pos = mapping.pos(bin+1,dim);
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BBox3fa left,right;
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splitter(rest,dim,pos,left,right);
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if (unlikely(left.empty())) l++;
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extend(dim,bin,left);
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rest = right;
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}
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if (unlikely(rest.empty())) r--;
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add(dim,l,r,bin,rest);
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}
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}
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}
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}
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/*! bins an array of primitives */
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__forceinline void binSubTreeRefs(const PrimRef* source, size_t begin, size_t end, const SpatialBinMapping<BINS>& mapping)
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{
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for (size_t i=begin; i<end; i++)
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{
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const PrimRef &prim = source[i];
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const vint4 bin0 = mapping.bin(prim.bounds().lower);
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const vint4 bin1 = mapping.bin(prim.bounds().upper);
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for (size_t dim=0; dim<3; dim++)
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{
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if (unlikely(mapping.invalid(dim)))
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continue;
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const size_t l = bin0[dim];
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const size_t r = bin1[dim];
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const unsigned int n = prim.primID();
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// same bin optimization
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if (likely(l == r))
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{
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add(dim,l,l,l,prim.bounds(),n);
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continue;
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}
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const size_t bin_start = bin0[dim];
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const size_t bin_end = bin1[dim];
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for (size_t bin=bin_start; bin<bin_end; bin++)
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add(dim,l,r,bin,prim.bounds(),n);
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}
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}
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}
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/*! merges in other binning information */
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void merge (const SpatialBinInfo& other)
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{
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for (size_t i=0; i<BINS; i++)
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{
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numBegin[i] += other.numBegin[i];
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numEnd [i] += other.numEnd [i];
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bounds[i][0].extend(other.bounds[i][0]);
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bounds[i][1].extend(other.bounds[i][1]);
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bounds[i][2].extend(other.bounds[i][2]);
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}
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}
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/*! merges in other binning information */
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static __forceinline const SpatialBinInfo reduce (const SpatialBinInfo& a, const SpatialBinInfo& b)
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{
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SpatialBinInfo c(empty);
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for (size_t i=0; i<BINS; i++)
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{
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c.numBegin[i] += a.numBegin[i]+b.numBegin[i];
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c.numEnd [i] += a.numEnd [i]+b.numEnd [i];
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c.bounds[i][0] = embree::merge(a.bounds[i][0],b.bounds[i][0]);
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c.bounds[i][1] = embree::merge(a.bounds[i][1],b.bounds[i][1]);
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c.bounds[i][2] = embree::merge(a.bounds[i][2],b.bounds[i][2]);
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}
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return c;
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}
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/*! finds the best split by scanning binning information */
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SpatialBinSplit<BINS> best(const SpatialBinMapping<BINS>& mapping, const size_t blocks_shift) const
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{
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/* sweep from right to left and compute parallel prefix of merged bounds */
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vfloat4 rAreas[BINS];
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vuint4 rCounts[BINS];
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vuint4 count = 0; BBox3fa bx = empty; BBox3fa by = empty; BBox3fa bz = empty;
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for (size_t i=BINS-1; i>0; i--)
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{
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count += numEnd[i];
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rCounts[i] = count;
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bx.extend(bounds[i][0]); rAreas[i][0] = halfArea(bx);
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by.extend(bounds[i][1]); rAreas[i][1] = halfArea(by);
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bz.extend(bounds[i][2]); rAreas[i][2] = halfArea(bz);
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rAreas[i][3] = 0.0f;
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}
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/* sweep from left to right and compute SAH */
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vuint4 blocks_add = (1 << blocks_shift)-1;
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vuint4 ii = 1; vfloat4 vbestSAH = pos_inf; vuint4 vbestPos = 0; vuint4 vbestlCount = 0; vuint4 vbestrCount = 0;
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count = 0; bx = empty; by = empty; bz = empty;
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for (size_t i=1; i<BINS; i++, ii+=1)
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{
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count += numBegin[i-1];
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bx.extend(bounds[i-1][0]); float Ax = halfArea(bx);
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by.extend(bounds[i-1][1]); float Ay = halfArea(by);
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bz.extend(bounds[i-1][2]); float Az = halfArea(bz);
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const vfloat4 lArea = vfloat4(Ax,Ay,Az,Az);
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const vfloat4 rArea = rAreas[i];
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const vuint4 lCount = (count +blocks_add) >> (unsigned int)(blocks_shift);
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const vuint4 rCount = (rCounts[i]+blocks_add) >> (unsigned int)(blocks_shift);
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const vfloat4 sah = madd(lArea,vfloat4(lCount),rArea*vfloat4(rCount));
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// const vfloat4 sah = madd(lArea,vfloat4(vint4(lCount)),rArea*vfloat4(vint4(rCount)));
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const vbool4 mask = sah < vbestSAH;
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vbestPos = select(mask,ii ,vbestPos);
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vbestSAH = select(mask,sah,vbestSAH);
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vbestlCount = select(mask,count,vbestlCount);
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vbestrCount = select(mask,rCounts[i],vbestrCount);
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}
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/* find best dimension */
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float bestSAH = inf;
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int bestDim = -1;
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int bestPos = 0;
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unsigned int bestlCount = 0;
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unsigned int bestrCount = 0;
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for (int dim=0; dim<3; dim++)
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{
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/* ignore zero sized dimensions */
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if (unlikely(mapping.invalid(dim)))
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continue;
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/* test if this is a better dimension */
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if (vbestSAH[dim] < bestSAH && vbestPos[dim] != 0) {
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bestDim = dim;
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bestPos = vbestPos[dim];
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bestSAH = vbestSAH[dim];
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bestlCount = vbestlCount[dim];
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bestrCount = vbestrCount[dim];
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}
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}
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assert(bestSAH >= 0.0f);
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/* return invalid split if no split found */
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if (bestDim == -1)
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return SpatialBinSplit<BINS>(inf,-1,0,mapping);
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/* return best found split */
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return SpatialBinSplit<BINS>(bestSAH,bestDim,bestPos,bestlCount,bestrCount,1.0f,mapping);
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}
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private:
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BBox3fa bounds[BINS][3]; //!< geometry bounds for each bin in each dimension
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vuint4 numBegin[BINS]; //!< number of primitives starting in bin
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vuint4 numEnd[BINS]; //!< number of primitives ending in bin
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};
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}
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}
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