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/*
* Adapted from code copyright 2009-2011 Intel Corporation
* Modifications Copyright 2012, Blender Foundation.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
//#define __KERNEL_SSE__
#include <stdlib.h>
#include "bvh_binning.h"
#include "util_algorithm.h"
#include "util_boundbox.h"
#include "util_types.h"
CCL_NAMESPACE_BEGIN
/* SSE replacements */
__forceinline void prefetch_L1 (const void* ptr) { }
__forceinline void prefetch_L2 (const void* ptr) { }
__forceinline void prefetch_L3 (const void* ptr) { }
__forceinline void prefetch_NTA(const void* ptr) { }
template<size_t src> __forceinline float extract(const int4& b)
{ return b[src]; }
template<size_t dst> __forceinline const float4 insert(const float4& a, const float b)
{ float4 r = a; r[dst] = b; return r; }
__forceinline int get_best_dimension(const float4& bestSAH)
{
// return (int)__bsf(movemask(reduce_min(bestSAH) == bestSAH));
float minSAH = min(bestSAH.x, min(bestSAH.y, bestSAH.z));
if(bestSAH.x == minSAH) return 0;
else if(bestSAH.y == minSAH) return 1;
else return 2;
}
/* BVH Object Binning */
BVHObjectBinning::BVHObjectBinning(const BVHRange& job, BVHReference *prims)
: BVHRange(job), splitSAH(FLT_MAX), dim(0), pos(0)
{
/* compute number of bins to use and precompute scaling factor for binning */
num_bins = min(size_t(MAX_BINS), size_t(4.0f + 0.05f*size()));
scale = rcp(cent_bounds().size()) * make_float3((float)num_bins);
/* initialize binning counter and bounds */
BoundBox bin_bounds[MAX_BINS][4]; /* bounds for every bin in every dimension */
int4 bin_count[MAX_BINS]; /* number of primitives mapped to bin */
for(size_t i = 0; i < num_bins; i++) {
bin_count[i] = make_int4(0);
bin_bounds[i][0] = bin_bounds[i][1] = bin_bounds[i][2] = BoundBox::empty;
}
/* map geometry to bins, unrolled once */
{
ssize_t i;
for(i = 0; i < ssize_t(size()) - 1; i += 2) {
prefetch_L2(&prims[start() + i + 8]);
/* map even and odd primitive to bin */
BVHReference prim0 = prims[start() + i + 0];
BVHReference prim1 = prims[start() + i + 1];
int4 bin0 = get_bin(prim0.bounds());
int4 bin1 = get_bin(prim1.bounds());
/* increase bounds for bins for even primitive */
int b00 = extract<0>(bin0); bin_count[b00][0]++; bin_bounds[b00][0].grow(prim0.bounds());
int b01 = extract<1>(bin0); bin_count[b01][1]++; bin_bounds[b01][1].grow(prim0.bounds());
int b02 = extract<2>(bin0); bin_count[b02][2]++; bin_bounds[b02][2].grow(prim0.bounds());
/* increase bounds of bins for odd primitive */
int b10 = extract<0>(bin1); bin_count[b10][0]++; bin_bounds[b10][0].grow(prim1.bounds());
int b11 = extract<1>(bin1); bin_count[b11][1]++; bin_bounds[b11][1].grow(prim1.bounds());
int b12 = extract<2>(bin1); bin_count[b12][2]++; bin_bounds[b12][2].grow(prim1.bounds());
}
/* for uneven number of primitives */
if(i < ssize_t(size())) {
/* map primitive to bin */
BVHReference prim0 = prims[start() + i];
int4 bin0 = get_bin(prim0.bounds());
/* increase bounds of bins */
int b00 = extract<0>(bin0); bin_count[b00][0]++; bin_bounds[b00][0].grow(prim0.bounds());
int b01 = extract<1>(bin0); bin_count[b01][1]++; bin_bounds[b01][1].grow(prim0.bounds());
int b02 = extract<2>(bin0); bin_count[b02][2]++; bin_bounds[b02][2].grow(prim0.bounds());
}
}
/* sweep from right to left and compute parallel prefix of merged bounds */
float4 r_area[MAX_BINS]; /* area of bounds of primitives on the right */
float4 r_count[MAX_BINS]; /* number of primitives on the right */
int4 count = make_int4(0);
BoundBox bx = BoundBox::empty;
BoundBox by = BoundBox::empty;
BoundBox bz = BoundBox::empty;
for(size_t i = num_bins - 1; i > 0; i--) {
count = count + bin_count[i];
r_count[i] = blocks(count);
bx = merge(bx,bin_bounds[i][0]); r_area[i][0] = bx.half_area();
by = merge(by,bin_bounds[i][1]); r_area[i][1] = by.half_area();
bz = merge(bz,bin_bounds[i][2]); r_area[i][2] = bz.half_area();
r_area[i][3] = r_area[i][2];
}
/* sweep from left to right and compute SAH */
int4 ii = make_int4(1);
float4 bestSAH = make_float4(FLT_MAX);
int4 bestSplit = make_int4(-1);
count = make_int4(0);
bx = BoundBox::empty;
by = BoundBox::empty;
bz = BoundBox::empty;
for(size_t i = 1; i < num_bins; i++, ii += make_int4(1)) {
count = count + bin_count[i-1];
bx = merge(bx,bin_bounds[i-1][0]); float Ax = bx.half_area();
by = merge(by,bin_bounds[i-1][1]); float Ay = by.half_area();
bz = merge(bz,bin_bounds[i-1][2]); float Az = bz.half_area();
float4 lCount = blocks(count);
float4 lArea = make_float4(Ax,Ay,Az,Az);
float4 sah = lArea*lCount + r_area[i]*r_count[i];
bestSplit = select(sah < bestSAH,ii,bestSplit);
bestSAH = min(sah,bestSAH);
}
int4 mask = float3_to_float4(cent_bounds().size()) <= make_float4(0.0f);
bestSAH = insert<3>(select(mask, make_float4(FLT_MAX), bestSAH), FLT_MAX);
/* find best dimension */
dim = get_best_dimension(bestSAH);
splitSAH = bestSAH[dim];
pos = bestSplit[dim];
leafSAH = bounds().half_area() * blocks(size());
}
void BVHObjectBinning::split(BVHReference* prims, BVHObjectBinning& left_o, BVHObjectBinning& right_o) const
{
size_t N = size();
BoundBox lgeom_bounds = BoundBox::empty;
BoundBox rgeom_bounds = BoundBox::empty;
BoundBox lcent_bounds = BoundBox::empty;
BoundBox rcent_bounds = BoundBox::empty;
ssize_t l = 0, r = N-1;
while(l <= r) {
prefetch_L2(&prims[start() + l + 8]);
prefetch_L2(&prims[start() + r - 8]);
BVHReference prim = prims[start() + l];
float3 center = prim.bounds().center2();
if(get_bin(center)[dim] < pos) {
lgeom_bounds.grow(prim.bounds());
lcent_bounds.grow(center);
l++;
}
else {
rgeom_bounds.grow(prim.bounds());
rcent_bounds.grow(center);
swap(prims[start()+l],prims[start()+r]);
r--;
}
}
/* finish */
if(l != 0 && N-1-r != 0) {
right_o = BVHObjectBinning(BVHRange(rgeom_bounds, rcent_bounds, start() + l, N-1-r), prims);
left_o = BVHObjectBinning(BVHRange(lgeom_bounds, lcent_bounds, start(), l), prims);
return;
}
/* object medium split if we did not make progress, can happen when all
* primitives have same centroid */
lgeom_bounds = BoundBox::empty;
rgeom_bounds = BoundBox::empty;
lcent_bounds = BoundBox::empty;
rcent_bounds = BoundBox::empty;
for(size_t i = 0; i < N/2; i++) {
lgeom_bounds.grow(prims[start()+i].bounds());
lcent_bounds.grow(prims[start()+i].bounds().center2());
}
for(size_t i = N/2; i < N; i++) {
rgeom_bounds.grow(prims[start()+i].bounds());
rcent_bounds.grow(prims[start()+i].bounds().center2());
}
right_o = BVHObjectBinning(BVHRange(rgeom_bounds, rcent_bounds, start() + N/2, N/2 + N%2), prims);
left_o = BVHObjectBinning(BVHRange(lgeom_bounds, lcent_bounds, start(), N/2), prims);
}
CCL_NAMESPACE_END
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