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godot/thirdparty/embree/kernels/builders/primrefgen_presplit.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

372 lines
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// Copyright 2009-2021 Intel Corporation
// SPDX-License-Identifier: Apache-2.0
#pragma once
#include "../builders/primrefgen.h"
#include "../builders/heuristic_spatial.h"
#include "../builders/splitter.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 5
#define MAX_PRESPLITS_PER_PRIMITIVE (1<<MAX_PRESPLITS_PER_PRIMITIVE_LOG)
#define PRIORITY_CUTOFF_THRESHOLD 1.0f
#define PRIORITY_SPLIT_POS_WEIGHT 1.5f
namespace embree
{
namespace isa
{
struct PresplitItem
{
union {
float priority;
unsigned int data;
};
unsigned int index;
__forceinline operator unsigned() const
{
return reinterpret_cast<const unsigned&>(priority);
}
__forceinline bool operator < (const PresplitItem& item) const
{
return (priority < item.priority);
}
template<typename Mesh>
__forceinline static float compute_priority(const PrimRef &ref, Scene *scene, const Vec2i &mc)
{
const unsigned int geomID = ref.geomID();
const unsigned int primID = ref.primID();
const float area_aabb = area(ref.bounds());
const float area_prim = ((Mesh*)scene->get(geomID))->projectedPrimitiveArea(primID);
const unsigned int diff = 31 - lzcnt(mc.x^mc.y);
assert(area_prim <= area_aabb);
//const float priority = powf((area_aabb - area_prim) * powf(PRIORITY_SPLIT_POS_WEIGHT,(float)diff),1.0f/4.0f);
const float priority = sqrtf(sqrtf( (area_aabb - area_prim) * powf(PRIORITY_SPLIT_POS_WEIGHT,(float)diff) ));
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;
};
template<typename SplitterFactory>
void splitPrimitive(SplitterFactory &Splitter,
const PrimRef &prim,
const unsigned int geomID,
const unsigned int primID,
const unsigned int split_level,
const Vec3fa &grid_base,
const float grid_scale,
const float grid_extend,
PrimRef subPrims[MAX_PRESPLITS_PER_PRIMITIVE],
unsigned int& numSubPrims)
{
assert(split_level <= MAX_PRESPLITS_PER_PRIMITIVE_LOG);
if (split_level == 0)
{
assert(numSubPrims < MAX_PRESPLITS_PER_PRIMITIVE);
subPrims[numSubPrims++] = prim;
}
else
{
const Vec3fa lower = prim.lower;
const Vec3fa upper = prim.upper;
const Vec3fa glower = (lower-grid_base)*Vec3fa(grid_scale)+Vec3fa(0.2f);
const Vec3fa gupper = (upper-grid_base)*Vec3fa(grid_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))
{
assert(numSubPrims < MAX_PRESPLITS_PER_PRIMITIVE);
subPrims[numSubPrims++] = prim;
return;
}
/* 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 = grid_base[dim] + isplit * inv_grid_size * grid_extend;
assert(prim.lower[dim] <= fsplit &&
prim.upper[dim] >= fsplit);
/* split primitive */
const auto splitter = Splitter(prim);
BBox3fa left,right;
splitter(prim.bounds(),dim,fsplit,left,right);
assert(!left.empty());
assert(!right.empty());
splitPrimitive(Splitter,PrimRef(left ,geomID,primID),geomID,primID,split_level-1,grid_base,grid_scale,grid_extend,subPrims,numSubPrims);
splitPrimitive(Splitter,PrimRef(right,geomID,primID),geomID,primID,split_level-1,grid_base,grid_scale,grid_extend,subPrims,numSubPrims);
}
}
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;
}
__forceinline Vec2i computeMC(const Vec3fa &grid_base, const float grid_scale, const PrimRef &ref)
{
const Vec3fa lower = ref.lower;
const Vec3fa upper = ref.upper;
const Vec3fa glower = (lower-grid_base)*Vec3fa(grid_scale)+Vec3fa(0.2f);
const Vec3fa gupper = (upper-grid_base)*Vec3fa(grid_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);
}
template<typename Mesh, typename SplitterFactory>
PrimInfo createPrimRefArray_presplit(Scene* scene, Geometry::GTypeMask types, bool mblur, size_t numPrimRefs, mvector<PrimRef>& prims, BuildProgressMonitor& progressMonitor)
{
static const size_t MIN_STEP_SIZE = 128;
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); });
}
/* use correct number of primitives */
size_t numPrimitives = pinfo.size();
const size_t alloc_numPrimitives = prims.size();
const size_t numSplitPrimitivesBudget = alloc_numPrimitives - numPrimitives;
/* set up primitive splitter */
SplitterFactory Splitter(scene);
DBG_PRESPLIT(
const size_t org_numPrimitives = pinfo.size();
PRINT(numPrimitives);
PRINT(alloc_numPrimitives);
PRINT(numSplitPrimitivesBudget);
);
/* allocate double buffer presplit items */
const size_t presplit_allocation_size = sizeof(PresplitItem)*alloc_numPrimitives;
PresplitItem *presplitItem = (PresplitItem*)alignedMalloc(presplit_allocation_size,64);
PresplitItem *tmp_presplitItem = (PresplitItem*)alignedMalloc(presplit_allocation_size,64);
/* compute grid */
const Vec3fa grid_base = pinfo.geomBounds.lower;
const Vec3fa grid_diag = pinfo.geomBounds.size();
const float grid_extend = max(grid_diag.x,max(grid_diag.y,grid_diag.z));
const float grid_scale = grid_extend == 0.0f ? 0.0f : GRID_SIZE / grid_extend;
/* 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++)
{
presplitItem[i].index = (unsigned int)i;
const Vec2i mc = computeMC(grid_base,grid_scale,prims[i]);
/* if all bits are equal then we cannot split */
presplitItem[i].priority = (mc.x != mc.y) ? PresplitItem::compute_priority<Mesh>(prims[i],scene,mc) : 0.0f;
/* FIXME: sum undeterministic */
sum += presplitItem[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 (presplitItem[i].priority > 0.0f)
{
const float rel_p = (float)numSplitPrimitivesBudget * presplitItem[i].priority * inv_psum;
if (rel_p >= PRIORITY_CUTOFF_THRESHOLD) // need at least a split budget that generates two sub-prims
{
presplitItem[i].priority = max(min(ceilf(logf(rel_p)/logf(2.0f)),(float)MAX_PRESPLITS_PER_PRIMITIVE_LOG),1.0f);
//presplitItem[i].priority = min(floorf(logf(rel_p)/logf(2.0f)),(float)MAX_PRESPLITS_PER_PRIMITIVE_LOG);
assert(presplitItem[i].priority >= 0.0f && presplitItem[i].priority <= (float)MAX_PRESPLITS_PER_PRIMITIVE_LOG);
}
else
presplitItem[i].priority = 0.0f;
}
}
});
auto isLeft = [&] (const PresplitItem &ref) { return ref.priority < PRIORITY_CUTOFF_THRESHOLD; };
size_t center = parallel_partitioning(presplitItem,0,numPrimitives,isLeft,1024);
/* anything to split ? */
if (center < numPrimitives)
{
const size_t numPrimitivesToSplit = numPrimitives - center;
assert(presplitItem[center].priority >= 1.0f);
/* sort presplit items in ascending order */
radix_sort_u32(presplitItem + center,tmp_presplitItem + 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(presplitItem[i-1].priority <= presplitItem[i].priority);
});
);
unsigned int *const primOffset0 = (unsigned int*)tmp_presplitItem;
unsigned int *const primOffset1 = (unsigned int*)tmp_presplitItem + 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++)
{
PrimRef subPrims[MAX_PRESPLITS_PER_PRIMITIVE];
assert(presplitItem[i].priority >= 1.0f);
const unsigned int primrefID = presplitItem[i].index;
const float prio = presplitItem[i].priority;
const unsigned int geomID = prims[primrefID].geomID();
const unsigned int primID = prims[primrefID].primID();
const unsigned int split_levels = (unsigned int)prio;
unsigned int numSubPrims = 0;
splitPrimitive(Splitter,prims[primrefID],geomID,primID,split_levels,grid_base,grid_scale,grid_extend,subPrims,numSubPrims);
assert(numSubPrims);
numSubPrims--; // can reuse slot
sum+=numSubPrims;
presplitItem[i].data = (numSubPrims << MAX_PRESPLITS_PER_PRIMITIVE_LOG) | split_levels;
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 = presplitItem[new_center].data >> MAX_PRESPLITS_PER_PRIMITIVE_LOG;
if (unlikely(sum + numSubPrims >= numSplitPrimitivesBudget)) break;
sum += numSubPrims;
}
new_center++;
center = new_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>());
/* 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++)
{
PrimRef subPrims[MAX_PRESPLITS_PER_PRIMITIVE];
const unsigned int primrefID = presplitItem[j].index;
const unsigned int geomID = prims[primrefID].geomID();
const unsigned int primID = prims[primrefID].primID();
const unsigned int split_levels = presplitItem[j].data & ((unsigned int)(1 << MAX_PRESPLITS_PER_PRIMITIVE_LOG)-1);
assert(split_levels);
assert(split_levels <= MAX_PRESPLITS_PER_PRIMITIVE_LOG);
unsigned int numSubPrims = 0;
splitPrimitive(Splitter,prims[primrefID],geomID,primID,split_levels,grid_base,grid_scale,grid_extend,subPrims,numSubPrims);
const size_t newID = numPrimitives + primOffset1[j-center];
assert(newID+numSubPrims <= alloc_numPrimitives);
prims[primrefID] = subPrims[0];
for (size_t i=1;i<numSubPrims;i++)
prims[newID+i-1] = subPrims[i];
}
});
numPrimitives += offset;
DBG_PRESPLIT(
PRINT(pinfo.size());
PRINT(numPrimitives);
PRINT((float)numPrimitives/org_numPrimitives));
}
/* recompute centroid bounding boxes */
pinfo = 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(pinfo.size() == numPrimitives);
/* free double buffer presplit items */
alignedFree(tmp_presplitItem);
alignedFree(presplitItem);
return pinfo;
}
}
}
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