virtualx-engine/thirdparty/embree/kernels/builders/heuristic_spatial.h
jfons 767e374dce Upgrade Embree to the latest official release.
Since Embree v3.13.0 supports AARCH64, switch back to the
official repo instead of using Embree-aarch64.

`thirdparty/embree/patches/godot-changes.patch` should now contain
an accurate diff of the changes done to the library.
2021-05-21 17:00:24 +02:00

414 lines
15 KiB
C++

// Copyright 2009-2021 Intel Corporation
// SPDX-License-Identifier: Apache-2.0
#pragma once
#include "../common/scene.h"
#include "priminfo.h"
namespace embree
{
static const unsigned int RESERVED_NUM_SPATIAL_SPLITS_GEOMID_BITS = 5;
namespace isa
{
/*! mapping into bins */
template<size_t BINS>
struct SpatialBinMapping
{
public:
__forceinline SpatialBinMapping() {}
/*! calculates the mapping */
__forceinline SpatialBinMapping(const CentGeomBBox3fa& pinfo)
{
const vfloat4 lower = (vfloat4) pinfo.geomBounds.lower;
const vfloat4 upper = (vfloat4) pinfo.geomBounds.upper;
const vfloat4 eps = 128.0f*vfloat4(ulp)*max(abs(lower),abs(upper));
const vfloat4 diag = max(eps,(vfloat4) pinfo.geomBounds.size());
scale = select(upper-lower <= eps,vfloat4(0.0f),vfloat4(BINS)/diag);
ofs = (vfloat4) pinfo.geomBounds.lower;
inv_scale = 1.0f / scale;
}
/*! slower but safe binning */
__forceinline vint4 bin(const Vec3fa& p) const
{
const vint4 i = floori((vfloat4(p)-ofs)*scale);
return clamp(i,vint4(0),vint4(BINS-1));
}
__forceinline std::pair<vint4,vint4> bin(const BBox3fa& b) const
{
#if defined(__AVX__)
const vfloat8 ofs8(ofs);
const vfloat8 scale8(scale);
const vint8 lu = floori((vfloat8::loadu(&b)-ofs8)*scale8);
const vint8 c_lu = clamp(lu,vint8(zero),vint8(BINS-1));
return std::pair<vint4,vint4>(extract4<0>(c_lu),extract4<1>(c_lu));
#else
const vint4 lower = floori((vfloat4(b.lower)-ofs)*scale);
const vint4 upper = floori((vfloat4(b.upper)-ofs)*scale);
const vint4 c_lower = clamp(lower,vint4(0),vint4(BINS-1));
const vint4 c_upper = clamp(upper,vint4(0),vint4(BINS-1));
return std::pair<vint4,vint4>(c_lower,c_upper);
#endif
}
/*! calculates left spatial position of bin */
__forceinline float pos(const size_t bin, const size_t dim) const {
return madd(float(bin),inv_scale[dim],ofs[dim]);
}
/*! calculates left spatial position of bin */
template<size_t N>
__forceinline vfloat<N> posN(const vfloat<N> bin, const size_t dim) const {
return madd(bin,vfloat<N>(inv_scale[dim]),vfloat<N>(ofs[dim]));
}
/*! returns true if the mapping is invalid in some dimension */
__forceinline bool invalid(const size_t dim) const {
return scale[dim] == 0.0f;
}
public:
vfloat4 ofs,scale,inv_scale; //!< linear function that maps to bin ID
};
/*! stores all information required to perform some split */
template<size_t BINS>
struct SpatialBinSplit
{
/*! construct an invalid split by default */
__forceinline SpatialBinSplit()
: sah(inf), dim(-1), pos(0), left(-1), right(-1), factor(1.0f) {}
/*! constructs specified split */
__forceinline SpatialBinSplit(float sah, int dim, int pos, const SpatialBinMapping<BINS>& mapping)
: sah(sah), dim(dim), pos(pos), left(-1), right(-1), factor(1.0f), mapping(mapping) {}
/*! constructs specified split */
__forceinline SpatialBinSplit(float sah, int dim, int pos, int left, int right, float factor, const SpatialBinMapping<BINS>& mapping)
: sah(sah), dim(dim), pos(pos), left(left), right(right), factor(factor), mapping(mapping) {}
/*! tests if this split is valid */
__forceinline bool valid() const { return dim != -1; }
/*! calculates surface area heuristic for performing the split */
__forceinline float splitSAH() const { return sah; }
/*! stream output */
friend embree_ostream operator<<(embree_ostream cout, const SpatialBinSplit& split) {
return cout << "SpatialBinSplit { sah = " << split.sah << ", dim = " << split.dim << ", pos = " << split.pos << ", left = " << split.left << ", right = " << split.right << ", factor = " << split.factor << "}";
}
public:
float sah; //!< SAH cost of the split
int dim; //!< split dimension
int pos; //!< split position
int left; //!< number of elements on the left side
int right; //!< number of elements on the right side
float factor; //!< factor splitting the extended range
SpatialBinMapping<BINS> mapping; //!< mapping into bins
};
/*! stores all binning information */
template<size_t BINS, typename PrimRef>
struct __aligned(64) SpatialBinInfo
{
SpatialBinInfo() {
}
__forceinline SpatialBinInfo(EmptyTy) {
clear();
}
/*! clears the bin info */
__forceinline void clear()
{
for (size_t i=0; i<BINS; i++) {
bounds[i][0] = bounds[i][1] = bounds[i][2] = empty;
numBegin[i] = numEnd[i] = 0;
}
}
/*! adds binning data */
__forceinline void add(const size_t dim,
const size_t beginID,
const size_t endID,
const size_t binID,
const BBox3fa &b,
const size_t n = 1)
{
assert(beginID < BINS);
assert(endID < BINS);
assert(binID < BINS);
numBegin[beginID][dim]+=(unsigned int)n;
numEnd [endID][dim]+=(unsigned int)n;
bounds [binID][dim].extend(b);
}
/*! extends binning bounds */
__forceinline void extend(const size_t dim,
const size_t binID,
const BBox3fa &b)
{
assert(binID < BINS);
bounds [binID][dim].extend(b);
}
/*! bins an array of triangles */
template<typename SplitPrimitive>
__forceinline void bin(const SplitPrimitive& splitPrimitive, const PrimRef* prims, size_t N, const SpatialBinMapping<BINS>& mapping)
{
for (size_t i=0; i<N; i++)
{
const PrimRef prim = prims[i];
unsigned splits = prim.geomID() >> (32-RESERVED_NUM_SPATIAL_SPLITS_GEOMID_BITS);
if (unlikely(splits == 1))
{
const vint4 bin = mapping.bin(center(prim.bounds()));
for (size_t dim=0; dim<3; dim++)
{
assert(bin[dim] >= (int)0 && bin[dim] < (int)BINS);
numBegin[bin[dim]][dim]++;
numEnd [bin[dim]][dim]++;
bounds [bin[dim]][dim].extend(prim.bounds());
}
}
else
{
const vint4 bin0 = mapping.bin(prim.bounds().lower);
const vint4 bin1 = mapping.bin(prim.bounds().upper);
for (size_t dim=0; dim<3; dim++)
{
size_t bin;
PrimRef rest = prim;
size_t l = bin0[dim];
size_t r = bin1[dim];
// same bin optimization
if (likely(l == r))
{
numBegin[l][dim]++;
numEnd [l][dim]++;
bounds [l][dim].extend(prim.bounds());
continue;
}
for (bin=(size_t)bin0[dim]; bin<(size_t)bin1[dim]; bin++)
{
const float pos = mapping.pos(bin+1,dim);
PrimRef left,right;
splitPrimitive(rest,(int)dim,pos,left,right);
if (unlikely(left.bounds().empty())) l++;
bounds[bin][dim].extend(left.bounds());
rest = right;
}
if (unlikely(rest.bounds().empty())) r--;
numBegin[l][dim]++;
numEnd [r][dim]++;
bounds [bin][dim].extend(rest.bounds());
}
}
}
}
/*! bins a range of primitives inside an array */
template<typename SplitPrimitive>
void bin(const SplitPrimitive& splitPrimitive, const PrimRef* prims, size_t begin, size_t end, const SpatialBinMapping<BINS>& mapping) {
bin(splitPrimitive,prims+begin,end-begin,mapping);
}
/*! bins an array of primitives */
template<typename PrimitiveSplitterFactory>
__forceinline void bin2(const PrimitiveSplitterFactory& splitterFactory, const PrimRef* source, size_t begin, size_t end, const SpatialBinMapping<BINS>& mapping)
{
for (size_t i=begin; i<end; i++)
{
const PrimRef &prim = source[i];
const vint4 bin0 = mapping.bin(prim.bounds().lower);
const vint4 bin1 = mapping.bin(prim.bounds().upper);
for (size_t dim=0; dim<3; dim++)
{
if (unlikely(mapping.invalid(dim)))
continue;
size_t bin;
size_t l = bin0[dim];
size_t r = bin1[dim];
// same bin optimization
if (likely(l == r))
{
add(dim,l,l,l,prim.bounds());
continue;
}
const size_t bin_start = bin0[dim];
const size_t bin_end = bin1[dim];
BBox3fa rest = prim.bounds();
const auto splitter = splitterFactory(prim);
for (bin=bin_start; bin<bin_end; bin++)
{
const float pos = mapping.pos(bin+1,dim);
BBox3fa left,right;
splitter(rest,dim,pos,left,right);
if (unlikely(left.empty())) l++;
extend(dim,bin,left);
rest = right;
}
if (unlikely(rest.empty())) r--;
add(dim,l,r,bin,rest);
}
}
}
/*! bins an array of primitives */
__forceinline void binSubTreeRefs(const PrimRef* source, size_t begin, size_t end, const SpatialBinMapping<BINS>& mapping)
{
for (size_t i=begin; i<end; i++)
{
const PrimRef &prim = source[i];
const vint4 bin0 = mapping.bin(prim.bounds().lower);
const vint4 bin1 = mapping.bin(prim.bounds().upper);
for (size_t dim=0; dim<3; dim++)
{
if (unlikely(mapping.invalid(dim)))
continue;
const size_t l = bin0[dim];
const size_t r = bin1[dim];
const unsigned int n = prim.primID();
// same bin optimization
if (likely(l == r))
{
add(dim,l,l,l,prim.bounds(),n);
continue;
}
const size_t bin_start = bin0[dim];
const size_t bin_end = bin1[dim];
for (size_t bin=bin_start; bin<bin_end; bin++)
add(dim,l,r,bin,prim.bounds(),n);
}
}
}
/*! merges in other binning information */
void merge (const SpatialBinInfo& other)
{
for (size_t i=0; i<BINS; i++)
{
numBegin[i] += other.numBegin[i];
numEnd [i] += other.numEnd [i];
bounds[i][0].extend(other.bounds[i][0]);
bounds[i][1].extend(other.bounds[i][1]);
bounds[i][2].extend(other.bounds[i][2]);
}
}
/*! merges in other binning information */
static __forceinline const SpatialBinInfo reduce (const SpatialBinInfo& a, const SpatialBinInfo& b)
{
SpatialBinInfo c(empty);
for (size_t i=0; i<BINS; i++)
{
c.numBegin[i] += a.numBegin[i]+b.numBegin[i];
c.numEnd [i] += a.numEnd [i]+b.numEnd [i];
c.bounds[i][0] = embree::merge(a.bounds[i][0],b.bounds[i][0]);
c.bounds[i][1] = embree::merge(a.bounds[i][1],b.bounds[i][1]);
c.bounds[i][2] = embree::merge(a.bounds[i][2],b.bounds[i][2]);
}
return c;
}
/*! finds the best split by scanning binning information */
SpatialBinSplit<BINS> best(const SpatialBinMapping<BINS>& mapping, const size_t blocks_shift) const
{
/* sweep from right to left and compute parallel prefix of merged bounds */
vfloat4 rAreas[BINS];
vuint4 rCounts[BINS];
vuint4 count = 0; BBox3fa bx = empty; BBox3fa by = empty; BBox3fa bz = empty;
for (size_t i=BINS-1; i>0; i--)
{
count += numEnd[i];
rCounts[i] = count;
bx.extend(bounds[i][0]); rAreas[i][0] = halfArea(bx);
by.extend(bounds[i][1]); rAreas[i][1] = halfArea(by);
bz.extend(bounds[i][2]); rAreas[i][2] = halfArea(bz);
rAreas[i][3] = 0.0f;
}
/* sweep from left to right and compute SAH */
vuint4 blocks_add = (1 << blocks_shift)-1;
vuint4 ii = 1; vfloat4 vbestSAH = pos_inf; vuint4 vbestPos = 0; vuint4 vbestlCount = 0; vuint4 vbestrCount = 0;
count = 0; bx = empty; by = empty; bz = empty;
for (size_t i=1; i<BINS; i++, ii+=1)
{
count += numBegin[i-1];
bx.extend(bounds[i-1][0]); float Ax = halfArea(bx);
by.extend(bounds[i-1][1]); float Ay = halfArea(by);
bz.extend(bounds[i-1][2]); float Az = halfArea(bz);
const vfloat4 lArea = vfloat4(Ax,Ay,Az,Az);
const vfloat4 rArea = rAreas[i];
const vuint4 lCount = (count +blocks_add) >> (unsigned int)(blocks_shift);
const vuint4 rCount = (rCounts[i]+blocks_add) >> (unsigned int)(blocks_shift);
const vfloat4 sah = madd(lArea,vfloat4(lCount),rArea*vfloat4(rCount));
// const vfloat4 sah = madd(lArea,vfloat4(vint4(lCount)),rArea*vfloat4(vint4(rCount)));
const vbool4 mask = sah < vbestSAH;
vbestPos = select(mask,ii ,vbestPos);
vbestSAH = select(mask,sah,vbestSAH);
vbestlCount = select(mask,count,vbestlCount);
vbestrCount = select(mask,rCounts[i],vbestrCount);
}
/* find best dimension */
float bestSAH = inf;
int bestDim = -1;
int bestPos = 0;
unsigned int bestlCount = 0;
unsigned int bestrCount = 0;
for (int dim=0; dim<3; dim++)
{
/* ignore zero sized dimensions */
if (unlikely(mapping.invalid(dim)))
continue;
/* test if this is a better dimension */
if (vbestSAH[dim] < bestSAH && vbestPos[dim] != 0) {
bestDim = dim;
bestPos = vbestPos[dim];
bestSAH = vbestSAH[dim];
bestlCount = vbestlCount[dim];
bestrCount = vbestrCount[dim];
}
}
assert(bestSAH >= 0.0f);
/* return invalid split if no split found */
if (bestDim == -1)
return SpatialBinSplit<BINS>(inf,-1,0,mapping);
/* return best found split */
return SpatialBinSplit<BINS>(bestSAH,bestDim,bestPos,bestlCount,bestrCount,1.0f,mapping);
}
private:
BBox3fa bounds[BINS][3]; //!< geometry bounds for each bin in each dimension
vuint4 numBegin[BINS]; //!< number of primitives starting in bin
vuint4 numEnd[BINS]; //!< number of primitives ending in bin
};
}
}