virtualx-engine/thirdparty/embree/kernels/builders/primrefgen_presplit.h
Jakub Mateusz Marcowski c43eab55a4
embree: Update to 4.3.1
2024-03-27 22:10:35 +01:00

468 lines
19 KiB
C++

// Copyright 2009-2021 Intel Corporation
// SPDX-License-Identifier: Apache-2.0
#pragma once
#include "../../common/algorithms/parallel_reduce.h"
#include "../../common/algorithms/parallel_sort.h"
#include "../builders/heuristic_spatial.h"
#include "../builders/splitter.h"
#include "../../common/algorithms/parallel_partition.h"
#include "../../common/algorithms/parallel_for_for.h"
#include "../../common/algorithms/parallel_for_for_prefix_sum.h"
#define DBG_PRESPLIT(x)
#define CHECK_PRESPLIT(x)
#define GRID_SIZE 1024
//#define MAX_PRESPLITS_PER_PRIMITIVE_LOG 6
#define MAX_PRESPLITS_PER_PRIMITIVE_LOG 5
#define MAX_PRESPLITS_PER_PRIMITIVE (1<<MAX_PRESPLITS_PER_PRIMITIVE_LOG)
//#define PRIORITY_CUTOFF_THRESHOLD 2.0f
#define PRIORITY_SPLIT_POS_WEIGHT 1.5f
namespace embree
{
namespace isa
{
struct SplittingGrid
{
__forceinline SplittingGrid(const BBox3fa& bounds)
{
base = bounds.lower;
const Vec3fa diag = bounds.size();
extend = max(diag.x,max(diag.y,diag.z));
scale = extend == 0.0f ? 0.0f : GRID_SIZE / extend;
}
__forceinline bool split_pos(const PrimRef& prim, unsigned int& dim_o, float& fsplit_o) const
{
/* compute morton code */
const Vec3fa lower = prim.lower;
const Vec3fa upper = prim.upper;
const Vec3fa glower = (lower-base)*Vec3fa(scale)+Vec3fa(0.2f);
const Vec3fa gupper = (upper-base)*Vec3fa(scale)-Vec3fa(0.2f);
Vec3ia ilower(floor(glower));
Vec3ia iupper(floor(gupper));
/* this ignores dimensions that are empty */
iupper = (Vec3ia)select(vint4(glower) >= vint4(gupper),vint4(ilower),vint4(iupper));
/* compute a morton code for the lower and upper grid coordinates. */
const unsigned int lower_code = bitInterleave(ilower.x,ilower.y,ilower.z);
const unsigned int upper_code = bitInterleave(iupper.x,iupper.y,iupper.z);
/* if all bits are equal then we cannot split */
if (unlikely(lower_code == upper_code))
return false;
/* compute octree level and dimension to perform the split in */
const unsigned int diff = 31 - lzcnt(lower_code^upper_code);
const unsigned int level = diff / 3;
const unsigned int dim = diff % 3;
/* now we compute the grid position of the split */
const unsigned int isplit = iupper[dim] & ~((1<<level)-1);
/* compute world space position of split */
const float inv_grid_size = 1.0f / GRID_SIZE;
const float fsplit = base[dim] + isplit * inv_grid_size * extend;
assert(prim.lower[dim] <= fsplit && prim.upper[dim] >= fsplit);
dim_o = dim;
fsplit_o = fsplit;
return true;
}
__forceinline Vec2i computeMC(const PrimRef& ref) const
{
const Vec3fa lower = ref.lower;
const Vec3fa upper = ref.upper;
const Vec3fa glower = (lower-base)*Vec3fa(scale)+Vec3fa(0.2f);
const Vec3fa gupper = (upper-base)*Vec3fa(scale)-Vec3fa(0.2f);
Vec3ia ilower(floor(glower));
Vec3ia iupper(floor(gupper));
/* this ignores dimensions that are empty */
iupper = (Vec3ia)select(vint4(glower) >= vint4(gupper),vint4(ilower),vint4(iupper));
/* compute a morton code for the lower and upper grid coordinates. */
const unsigned int lower_code = bitInterleave(ilower.x,ilower.y,ilower.z);
const unsigned int upper_code = bitInterleave(iupper.x,iupper.y,iupper.z);
return Vec2i(lower_code,upper_code);
}
Vec3fa base;
float scale;
float extend;
};
struct PresplitItem
{
union {
float priority;
unsigned int data;
};
unsigned int index;
__forceinline operator unsigned() const {
return data;
}
template<typename ProjectedPrimitiveAreaFunc>
__forceinline static float compute_priority(const ProjectedPrimitiveAreaFunc& primitiveArea, const PrimRef &ref, const Vec2i &mc)
{
const float area_aabb = area(ref.bounds());
const float area_prim = primitiveArea(ref);
if (area_prim == 0.0f) return 0.0f;
const unsigned int diff = 31 - lzcnt(mc.x^mc.y);
//assert(area_prim <= area_aabb); // may trigger due to numerical issues
const float area_diff = max(0.0f, area_aabb - area_prim);
//const float priority = powf(area_diff * powf(PRIORITY_SPLIT_POS_WEIGHT,(float)diff),1.0f/4.0f);
const float priority = sqrtf(sqrtf( area_diff * powf(PRIORITY_SPLIT_POS_WEIGHT,(float)diff) ));
//const float priority = sqrtf(sqrtf( area_diff ) );
//const float priority = sqrtfarea_diff;
//const float priority = area_diff; // 104 fps !!!!!!!!!!
//const float priority = 0.2f*area_aabb + 0.8f*area_diff; // 104 fps
//const float priority = area_aabb * max(area_aabb/area_prim,32.0f);
//const float priority = area_prim;
assert(priority >= 0.0f && priority < FLT_LARGE);
return priority;
}
};
inline std::ostream &operator<<(std::ostream &cout, const PresplitItem& item) {
return cout << "index " << item.index << " priority " << item.priority;
};
#if 1
template<typename Splitter>
void splitPrimitive(const Splitter& splitter,
const PrimRef& prim,
const unsigned int splitprims,
const SplittingGrid& grid,
PrimRef subPrims[MAX_PRESPLITS_PER_PRIMITIVE],
unsigned int& numSubPrims)
{
assert(splitprims > 0 && splitprims <= MAX_PRESPLITS_PER_PRIMITIVE);
if (splitprims == 1)
{
assert(numSubPrims < MAX_PRESPLITS_PER_PRIMITIVE);
subPrims[numSubPrims++] = prim;
}
else
{
unsigned int dim; float fsplit;
if (!grid.split_pos(prim, dim, fsplit))
{
assert(numSubPrims < MAX_PRESPLITS_PER_PRIMITIVE);
subPrims[numSubPrims++] = prim;
return;
}
/* split primitive */
PrimRef left,right;
splitter(prim,dim,fsplit,left,right);
assert(!left.bounds().empty());
assert(!right.bounds().empty());
const unsigned int splitprims_left = splitprims/2;
const unsigned int splitprims_right = splitprims - splitprims_left;
splitPrimitive(splitter,left,splitprims_left,grid,subPrims,numSubPrims);
splitPrimitive(splitter,right,splitprims_right,grid,subPrims,numSubPrims);
}
}
#else
template<typename Splitter>
void splitPrimitive(const Splitter& splitter,
const PrimRef& prim,
const unsigned int targetSubPrims,
const SplittingGrid& grid,
PrimRef subPrims[MAX_PRESPLITS_PER_PRIMITIVE],
unsigned int& numSubPrims)
{
assert(targetSubPrims > 0 && targetSubPrims <= MAX_PRESPLITS_PER_PRIMITIVE);
auto compare = [] ( const PrimRef& a, const PrimRef& b ) {
return area(a.bounds()) < area(b.bounds());
};
subPrims[numSubPrims++] = prim;
while (numSubPrims < targetSubPrims)
{
/* get top heap element */
std::pop_heap(subPrims+0,subPrims+numSubPrims, compare);
PrimRef top = subPrims[--numSubPrims];
unsigned int dim; float fsplit;
if (!grid.split_pos(top, dim, fsplit))
{
assert(numSubPrims < MAX_PRESPLITS_PER_PRIMITIVE);
subPrims[numSubPrims++] = top;
return;
}
/* split primitive */
PrimRef left,right;
splitter(top,dim,fsplit,left,right);
assert(!left.bounds().empty());
assert(!right.bounds().empty());
subPrims[numSubPrims++] = left;
std::push_heap(subPrims+0, subPrims+numSubPrims, compare);
subPrims[numSubPrims++] = right;
std::push_heap(subPrims+0, subPrims+numSubPrims, compare);
}
}
#endif
#if !defined(RTHWIF_STANDALONE)
template<typename Mesh, typename SplitterFactory>
PrimInfo createPrimRefArray_presplit(Geometry* geometry, unsigned int geomID, size_t numPrimRefs, mvector<PrimRef>& prims, BuildProgressMonitor& progressMonitor)
{
ParallelPrefixSumState<PrimInfo> pstate;
/* first try */
progressMonitor(0);
PrimInfo pinfo = parallel_prefix_sum( pstate, size_t(0), geometry->size(), size_t(1024), PrimInfo(empty), [&](const range<size_t>& r, const PrimInfo& base) -> PrimInfo {
return geometry->createPrimRefArray(prims,r,r.begin(),geomID);
}, [](const PrimInfo& a, const PrimInfo& b) -> PrimInfo { return PrimInfo::merge(a,b); });
/* if we need to filter out geometry, run again */
if (pinfo.size() != numPrimRefs)
{
progressMonitor(0);
pinfo = parallel_prefix_sum( pstate, size_t(0), geometry->size(), size_t(1024), PrimInfo(empty), [&](const range<size_t>& r, const PrimInfo& base) -> PrimInfo {
return geometry->createPrimRefArray(prims,r,base.size(),geomID);
}, [](const PrimInfo& a, const PrimInfo& b) -> PrimInfo { return PrimInfo::merge(a,b); });
}
return pinfo;
}
#endif
template<typename SplitPrimitiveFunc, typename ProjectedPrimitiveAreaFunc, typename PrimVector>
PrimInfo createPrimRefArray_presplit(size_t numPrimRefs,
PrimVector& prims,
const PrimInfo& pinfo,
const SplitPrimitiveFunc& splitPrimitive,
const ProjectedPrimitiveAreaFunc& primitiveArea)
{
static const size_t MIN_STEP_SIZE = 128;
/* use correct number of primitives */
size_t numPrimitives = pinfo.size();
const size_t numPrimitivesExt = prims.size();
const size_t numSplitPrimitivesBudget = numPrimitivesExt - numPrimitives;
/* allocate double buffer presplit items */
avector<PresplitItem> preSplitItem0(numPrimitivesExt);
avector<PresplitItem> preSplitItem1(numPrimitivesExt);
/* compute grid */
SplittingGrid grid(pinfo.geomBounds);
/* init presplit items and get total sum */
const float psum = parallel_reduce( size_t(0), numPrimitives, size_t(MIN_STEP_SIZE), 0.0f, [&](const range<size_t>& r) -> float {
float sum = 0.0f;
for (size_t i=r.begin(); i<r.end(); i++)
{
preSplitItem0[i].index = (unsigned int)i;
const Vec2i mc = grid.computeMC(prims[i]);
/* if all bits are equal then we cannot split */
preSplitItem0[i].priority = (mc.x != mc.y) ? PresplitItem::compute_priority(primitiveArea,prims[i],mc) : 0.0f;
/* FIXME: sum undeterministic */
sum += preSplitItem0[i].priority;
}
return sum;
},[](const float& a, const float& b) -> float { return a+b; });
/* compute number of splits per primitive */
const float inv_psum = 1.0f / psum;
parallel_for( size_t(0), numPrimitives, size_t(MIN_STEP_SIZE), [&](const range<size_t>& r) -> void {
for (size_t i=r.begin(); i<r.end(); i++)
{
if (preSplitItem0[i].priority <= 0.0f) {
preSplitItem0[i].data = 1;
continue;
}
const float rel_p = (float)numSplitPrimitivesBudget * preSplitItem0[i].priority * inv_psum;
if (rel_p < 1) {
preSplitItem0[i].data = 1;
continue;
}
//preSplitItem0[i].data = max(min(ceilf(rel_p),(float)MAX_PRESPLITS_PER_PRIMITIVE),1.0f);
preSplitItem0[i].data = max(min(ceilf(logf(rel_p)/logf(2.0f)),(float)MAX_PRESPLITS_PER_PRIMITIVE_LOG),1.0f);
preSplitItem0[i].data = 1 << preSplitItem0[i].data;
assert(preSplitItem0[i].data <= MAX_PRESPLITS_PER_PRIMITIVE);
}
});
auto isLeft = [&] (const PresplitItem &ref) { return ref.data <= 1; };
size_t center = parallel_partitioning(preSplitItem0.data(),0,numPrimitives,isLeft,1024);
assert(center <= numPrimitives);
/* anything to split ? */
if (center >= numPrimitives)
return pinfo;
size_t numPrimitivesToSplit = numPrimitives - center;
assert(preSplitItem0[center].data >= 1.0f);
/* sort presplit items in ascending order */
radix_sort_u32(preSplitItem0.data() + center,preSplitItem1.data() + center,numPrimitivesToSplit,1024);
CHECK_PRESPLIT(
parallel_for( size_t(center+1), numPrimitives, size_t(MIN_STEP_SIZE), [&](const range<size_t>& r) -> void {
for (size_t i=r.begin(); i<r.end(); i++)
assert(preSplitItem0[i-1].data <= preSplitItem0[i].data);
});
);
unsigned int* primOffset0 = (unsigned int*)preSplitItem1.data();
unsigned int* primOffset1 = (unsigned int*)preSplitItem1.data() + numPrimitivesToSplit;
/* compute actual number of sub-primitives generated within the [center;numPrimitives-1] range */
const size_t totalNumSubPrims = parallel_reduce( size_t(center), numPrimitives, size_t(MIN_STEP_SIZE), size_t(0), [&](const range<size_t>& t) -> size_t {
size_t sum = 0;
for (size_t i=t.begin(); i<t.end(); i++)
{
const unsigned int primrefID = preSplitItem0[i].index;
const unsigned int splitprims = preSplitItem0[i].data;
assert(splitprims >= 1 && splitprims <= MAX_PRESPLITS_PER_PRIMITIVE);
unsigned int numSubPrims = 0;
PrimRef subPrims[MAX_PRESPLITS_PER_PRIMITIVE];
splitPrimitive(prims[primrefID],splitprims,grid,subPrims,numSubPrims);
assert(numSubPrims);
numSubPrims--; // can reuse slot
sum+=numSubPrims;
preSplitItem0[i].data = (numSubPrims << 16) | splitprims;
primOffset0[i-center] = numSubPrims;
}
return sum;
},[](const size_t& a, const size_t& b) -> size_t { return a+b; });
/* if we are over budget, need to shrink the range */
if (totalNumSubPrims > numSplitPrimitivesBudget)
{
size_t new_center = numPrimitives-1;
size_t sum = 0;
for (;new_center>=center;new_center--)
{
const unsigned int numSubPrims = preSplitItem0[new_center].data >> 16;
if (unlikely(sum + numSubPrims >= numSplitPrimitivesBudget)) break;
sum += numSubPrims;
}
new_center++;
primOffset0 += new_center - center;
numPrimitivesToSplit -= new_center - center;
center = new_center;
assert(numPrimitivesToSplit == (numPrimitives - center));
}
/* parallel prefix sum to compute offsets for storing sub-primitives */
const unsigned int offset = parallel_prefix_sum(primOffset0,primOffset1,numPrimitivesToSplit,(unsigned int)0,std::plus<unsigned int>());
assert(numPrimitives+offset <= numPrimitivesExt);
/* iterate over range, and split primitives into sub primitives and append them to prims array */
parallel_for( size_t(center), numPrimitives, size_t(MIN_STEP_SIZE), [&](const range<size_t>& rn) -> void {
for (size_t j=rn.begin(); j<rn.end(); j++)
{
const unsigned int primrefID = preSplitItem0[j].index;
const unsigned int splitprims = preSplitItem0[j].data & 0xFFFF;
assert(splitprims >= 1 && splitprims <= MAX_PRESPLITS_PER_PRIMITIVE);
unsigned int numSubPrims = 0;
PrimRef subPrims[MAX_PRESPLITS_PER_PRIMITIVE];
splitPrimitive(prims[primrefID],splitprims,grid,subPrims,numSubPrims);
const unsigned int numSubPrimsExpected MAYBE_UNUSED = preSplitItem0[j].data >> 16;
assert(numSubPrims-1 == numSubPrimsExpected);
const size_t newID = numPrimitives + primOffset1[j-center];
assert(newID+numSubPrims-1 <= numPrimitivesExt);
prims[primrefID] = subPrims[0];
for (size_t i=1;i<numSubPrims;i++)
prims[newID+i-1] = subPrims[i];
}
});
numPrimitives += offset;
/* recompute centroid bounding boxes */
const PrimInfo pinfo1 = parallel_reduce(size_t(0),numPrimitives,size_t(MIN_STEP_SIZE),PrimInfo(empty),[&] (const range<size_t>& r) -> PrimInfo {
PrimInfo p(empty);
for (size_t j=r.begin(); j<r.end(); j++)
p.add_center2(prims[j]);
return p;
}, [](const PrimInfo& a, const PrimInfo& b) -> PrimInfo { return PrimInfo::merge(a,b); });
assert(pinfo1.size() == numPrimitives);
return pinfo1;
}
#if !defined(RTHWIF_STANDALONE)
template<typename Mesh, typename SplitterFactory>
PrimInfo createPrimRefArray_presplit(Scene* scene, Geometry::GTypeMask types, bool mblur, size_t numPrimRefs, mvector<PrimRef>& prims, BuildProgressMonitor& progressMonitor)
{
ParallelForForPrefixSumState<PrimInfo> pstate;
Scene::Iterator2 iter(scene,types,mblur);
/* first try */
progressMonitor(0);
pstate.init(iter,size_t(1024));
PrimInfo pinfo = parallel_for_for_prefix_sum0( pstate, iter, PrimInfo(empty), [&](Geometry* mesh, const range<size_t>& r, size_t k, size_t geomID) -> PrimInfo {
return mesh->createPrimRefArray(prims,r,k,(unsigned)geomID);
}, [](const PrimInfo& a, const PrimInfo& b) -> PrimInfo { return PrimInfo::merge(a,b); });
/* if we need to filter out geometry, run again */
if (pinfo.size() != numPrimRefs)
{
progressMonitor(0);
pinfo = parallel_for_for_prefix_sum1( pstate, iter, PrimInfo(empty), [&](Geometry* mesh, const range<size_t>& r, size_t k, size_t geomID, const PrimInfo& base) -> PrimInfo {
return mesh->createPrimRefArray(prims,r,base.size(),(unsigned)geomID);
}, [](const PrimInfo& a, const PrimInfo& b) -> PrimInfo { return PrimInfo::merge(a,b); });
}
SplitterFactory Splitter(scene);
auto split_primitive = [&] (const PrimRef &prim,
const unsigned int splitprims,
const SplittingGrid& grid,
PrimRef subPrims[MAX_PRESPLITS_PER_PRIMITIVE],
unsigned int& numSubPrims)
{
const auto splitter = Splitter(prim);
splitPrimitive(splitter,prim,splitprims,grid,subPrims,numSubPrims);
};
auto primitiveArea = [&] (const PrimRef &ref) {
const unsigned int geomID = ref.geomID();
const unsigned int primID = ref.primID();
return ((Mesh*)scene->get(geomID))->projectedPrimitiveArea(primID);
};
return createPrimRefArray_presplit(numPrimRefs,prims,pinfo,split_primitive,primitiveArea);
}
#endif
}
}