forked from bartvdbraak/blender
b03e66e75f
This is a special builder type which is allowed to orient nodes to strands direction, hence minimizing their surface area in comparison with axis-aligned nodes. Such nodes are much more efficient for hair rendering. Implementation of BVH builder is based on Embree, and generally idea there is to calculate axis-aligned SAH and oriented SAH and if SAH of oriented node is smaller than axis-aligned SAH we create unaligned node. We store both aligned and unaligned nodes in the same tree (which seems to be different from what Embree is doing) so we don't have any any extra calculations needed to set up hair ray for BVH traversal, hence avoiding any possible negative effect of this new BVH nodes type. This new builder is currently not in use, still need to make BVH traversal code aware of unaligned nodes.
554 lines
18 KiB
C++
554 lines
18 KiB
C++
/*
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* Adapted from code copyright 2009-2010 NVIDIA Corporation
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* Modifications Copyright 2011, Blender Foundation.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include "bvh_build.h"
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#include "bvh_split.h"
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#include "bvh_sort.h"
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#include "mesh.h"
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#include "object.h"
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#include "util_algorithm.h"
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CCL_NAMESPACE_BEGIN
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/* Object Split */
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BVHObjectSplit::BVHObjectSplit(BVHBuild *builder,
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BVHSpatialStorage *storage,
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const BVHRange& range,
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vector<BVHReference> *references,
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float nodeSAH,
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const BVHUnaligned *unaligned_heuristic,
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const Transform *aligned_space)
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: sah(FLT_MAX),
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dim(0),
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num_left(0),
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left_bounds(BoundBox::empty),
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right_bounds(BoundBox::empty),
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storage_(storage),
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references_(references),
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unaligned_heuristic_(unaligned_heuristic),
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aligned_space_(aligned_space)
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{
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const BVHReference *ref_ptr = &references_->at(range.start());
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float min_sah = FLT_MAX;
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storage_->right_bounds.resize(range.size());
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for(int dim = 0; dim < 3; dim++) {
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/* Sort references. */
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bvh_reference_sort(range.start(),
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range.end(),
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&references_->at(0),
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dim,
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unaligned_heuristic_,
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aligned_space_);
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/* sweep right to left and determine bounds. */
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BoundBox right_bounds = BoundBox::empty;
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for(int i = range.size() - 1; i > 0; i--) {
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BoundBox prim_bounds = get_prim_bounds(ref_ptr[i]);
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right_bounds.grow(prim_bounds);
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storage_->right_bounds[i - 1] = right_bounds;
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}
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/* sweep left to right and select lowest SAH. */
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BoundBox left_bounds = BoundBox::empty;
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for(int i = 1; i < range.size(); i++) {
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BoundBox prim_bounds = get_prim_bounds(ref_ptr[i - 1]);
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left_bounds.grow(prim_bounds);
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right_bounds = storage_->right_bounds[i - 1];
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float sah = nodeSAH +
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left_bounds.safe_area() * builder->params.primitive_cost(i) +
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right_bounds.safe_area() * builder->params.primitive_cost(range.size() - i);
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if(sah < min_sah) {
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min_sah = sah;
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this->sah = sah;
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this->dim = dim;
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this->num_left = i;
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this->left_bounds = left_bounds;
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this->right_bounds = right_bounds;
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}
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}
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}
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}
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void BVHObjectSplit::split(BVHRange& left,
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BVHRange& right,
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const BVHRange& range)
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{
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assert(references_->size() > 0);
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/* sort references according to split */
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bvh_reference_sort(range.start(),
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range.end(),
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&references_->at(0),
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this->dim,
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unaligned_heuristic_,
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aligned_space_);
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BoundBox effective_left_bounds, effective_right_bounds;
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const int num_right = range.size() - this->num_left;
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if(aligned_space_ == NULL) {
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effective_left_bounds = left_bounds;
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effective_right_bounds = right_bounds;
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}
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else {
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effective_left_bounds = BoundBox::empty;
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effective_right_bounds = BoundBox::empty;
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for(int i = 0; i < this->num_left; ++i) {
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BoundBox prim_boundbox = references_->at(range.start() + i).bounds();
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effective_left_bounds.grow(prim_boundbox);
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}
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for(int i = 0; i < num_right; ++i) {
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BoundBox prim_boundbox = references_->at(range.start() + this->num_left + i).bounds();
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effective_right_bounds.grow(prim_boundbox);
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}
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}
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/* split node ranges */
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left = BVHRange(effective_left_bounds, range.start(), this->num_left);
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right = BVHRange(effective_right_bounds, left.end(), num_right);
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}
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/* Spatial Split */
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BVHSpatialSplit::BVHSpatialSplit(const BVHBuild& builder,
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BVHSpatialStorage *storage,
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const BVHRange& range,
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vector<BVHReference> *references,
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float nodeSAH,
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const BVHUnaligned *unaligned_heuristic,
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const Transform *aligned_space)
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: sah(FLT_MAX),
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dim(0),
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pos(0.0f),
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storage_(storage),
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references_(references),
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unaligned_heuristic_(unaligned_heuristic),
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aligned_space_(aligned_space)
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{
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/* initialize bins. */
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BoundBox range_bounds;
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if(aligned_space == NULL) {
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range_bounds = range.bounds();
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}
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else {
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range_bounds = unaligned_heuristic->compute_aligned_boundbox(
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range,
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&references->at(0),
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*aligned_space);
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}
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float3 origin = range_bounds.min;
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float3 binSize = (range_bounds.max - origin) * (1.0f / (float)BVHParams::NUM_SPATIAL_BINS);
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float3 invBinSize = 1.0f / binSize;
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for(int dim = 0; dim < 3; dim++) {
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for(int i = 0; i < BVHParams::NUM_SPATIAL_BINS; i++) {
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BVHSpatialBin& bin = storage_->bins[dim][i];
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bin.bounds = BoundBox::empty;
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bin.enter = 0;
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bin.exit = 0;
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}
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}
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/* chop references into bins. */
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for(unsigned int refIdx = range.start(); refIdx < range.end(); refIdx++) {
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const BVHReference& ref = references_->at(refIdx);
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BoundBox prim_bounds = get_prim_bounds(ref);
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float3 firstBinf = (prim_bounds.min - origin) * invBinSize;
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float3 lastBinf = (prim_bounds.max - origin) * invBinSize;
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int3 firstBin = make_int3((int)firstBinf.x, (int)firstBinf.y, (int)firstBinf.z);
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int3 lastBin = make_int3((int)lastBinf.x, (int)lastBinf.y, (int)lastBinf.z);
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firstBin = clamp(firstBin, 0, BVHParams::NUM_SPATIAL_BINS - 1);
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lastBin = clamp(lastBin, firstBin, BVHParams::NUM_SPATIAL_BINS - 1);
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for(int dim = 0; dim < 3; dim++) {
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BVHReference currRef(get_prim_bounds(ref),
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ref.prim_index(),
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ref.prim_object(),
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ref.prim_type());
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for(int i = firstBin[dim]; i < lastBin[dim]; i++) {
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BVHReference leftRef, rightRef;
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split_reference(builder, leftRef, rightRef, currRef, dim, origin[dim] + binSize[dim] * (float)(i + 1));
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storage_->bins[dim][i].bounds.grow(leftRef.bounds());
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currRef = rightRef;
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}
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storage_->bins[dim][lastBin[dim]].bounds.grow(currRef.bounds());
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storage_->bins[dim][firstBin[dim]].enter++;
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storage_->bins[dim][lastBin[dim]].exit++;
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}
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}
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/* select best split plane. */
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storage_->right_bounds.resize(BVHParams::NUM_SPATIAL_BINS);
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for(int dim = 0; dim < 3; dim++) {
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/* sweep right to left and determine bounds. */
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BoundBox right_bounds = BoundBox::empty;
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for(int i = BVHParams::NUM_SPATIAL_BINS - 1; i > 0; i--) {
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right_bounds.grow(storage_->bins[dim][i].bounds);
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storage_->right_bounds[i - 1] = right_bounds;
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}
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/* sweep left to right and select lowest SAH. */
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BoundBox left_bounds = BoundBox::empty;
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int leftNum = 0;
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int rightNum = range.size();
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for(int i = 1; i < BVHParams::NUM_SPATIAL_BINS; i++) {
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left_bounds.grow(storage_->bins[dim][i - 1].bounds);
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leftNum += storage_->bins[dim][i - 1].enter;
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rightNum -= storage_->bins[dim][i - 1].exit;
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float sah = nodeSAH +
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left_bounds.safe_area() * builder.params.primitive_cost(leftNum) +
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storage_->right_bounds[i - 1].safe_area() * builder.params.primitive_cost(rightNum);
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if(sah < this->sah) {
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this->sah = sah;
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this->dim = dim;
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this->pos = origin[dim] + binSize[dim] * (float)i;
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}
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}
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}
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}
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void BVHSpatialSplit::split(BVHBuild *builder,
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BVHRange& left,
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BVHRange& right,
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const BVHRange& range)
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{
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/* Categorize references and compute bounds.
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*
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* Left-hand side: [left_start, left_end[
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* Uncategorized/split: [left_end, right_start[
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* Right-hand side: [right_start, refs.size()[ */
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vector<BVHReference>& refs = *references_;
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int left_start = range.start();
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int left_end = left_start;
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int right_start = range.end();
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int right_end = range.end();
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BoundBox left_bounds = BoundBox::empty;
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BoundBox right_bounds = BoundBox::empty;
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for(int i = left_end; i < right_start; i++) {
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BoundBox prim_bounds = get_prim_bounds(refs[i]);
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if(prim_bounds.max[this->dim] <= this->pos) {
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/* entirely on the left-hand side */
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left_bounds.grow(prim_bounds);
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swap(refs[i], refs[left_end++]);
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}
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else if(prim_bounds.min[this->dim] >= this->pos) {
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/* entirely on the right-hand side */
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right_bounds.grow(prim_bounds);
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swap(refs[i--], refs[--right_start]);
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}
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}
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/* Duplicate or unsplit references intersecting both sides.
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*
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* Duplication happens into a temporary pre-allocated vector in order to
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* reduce number of memmove() calls happening in vector.insert().
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*/
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vector<BVHReference>& new_refs = storage_->new_references;
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new_refs.clear();
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new_refs.reserve(right_start - left_end);
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while(left_end < right_start) {
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/* split reference. */
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BVHReference curr_ref(get_prim_bounds(refs[left_end]),
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refs[left_end].prim_index(),
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refs[left_end].prim_object(),
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refs[left_end].prim_type());
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BVHReference lref, rref;
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split_reference(*builder, lref, rref, curr_ref, this->dim, this->pos);
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/* compute SAH for duplicate/unsplit candidates. */
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BoundBox lub = left_bounds; // Unsplit to left: new left-hand bounds.
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BoundBox rub = right_bounds; // Unsplit to right: new right-hand bounds.
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BoundBox ldb = left_bounds; // Duplicate: new left-hand bounds.
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BoundBox rdb = right_bounds; // Duplicate: new right-hand bounds.
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lub.grow(curr_ref.bounds());
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rub.grow(curr_ref.bounds());
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ldb.grow(lref.bounds());
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rdb.grow(rref.bounds());
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float lac = builder->params.primitive_cost(left_end - left_start);
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float rac = builder->params.primitive_cost(right_end - right_start);
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float lbc = builder->params.primitive_cost(left_end - left_start + 1);
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float rbc = builder->params.primitive_cost(right_end - right_start + 1);
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float unsplitLeftSAH = lub.safe_area() * lbc + right_bounds.safe_area() * rac;
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float unsplitRightSAH = left_bounds.safe_area() * lac + rub.safe_area() * rbc;
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float duplicateSAH = ldb.safe_area() * lbc + rdb.safe_area() * rbc;
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float minSAH = min(min(unsplitLeftSAH, unsplitRightSAH), duplicateSAH);
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if(minSAH == unsplitLeftSAH) {
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/* unsplit to left */
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left_bounds = lub;
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left_end++;
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}
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else if(minSAH == unsplitRightSAH) {
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/* unsplit to right */
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right_bounds = rub;
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swap(refs[left_end], refs[--right_start]);
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}
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else {
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/* duplicate */
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left_bounds = ldb;
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right_bounds = rdb;
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refs[left_end++] = lref;
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new_refs.push_back(rref);
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right_end++;
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}
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}
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/* Insert duplicated references into actual array in one go. */
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if(new_refs.size() != 0) {
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refs.insert(refs.begin() + (right_end - new_refs.size()),
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new_refs.begin(),
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new_refs.end());
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}
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if(aligned_space_ != NULL) {
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left_bounds = right_bounds = BoundBox::empty;
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for(int i = left_start; i < left_end - left_start; ++i) {
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BoundBox prim_boundbox = references_->at(i).bounds();
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left_bounds.grow(prim_boundbox);
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}
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for(int i = right_start; i < right_end - right_start; ++i) {
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BoundBox prim_boundbox = references_->at(i).bounds();
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right_bounds.grow(prim_boundbox);
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}
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}
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left = BVHRange(left_bounds, left_start, left_end - left_start);
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right = BVHRange(right_bounds, right_start, right_end - right_start);
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}
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void BVHSpatialSplit::split_triangle_primitive(const Mesh *mesh,
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const Transform *tfm,
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int prim_index,
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int dim,
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float pos,
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BoundBox& left_bounds,
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BoundBox& right_bounds)
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{
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Mesh::Triangle t = mesh->get_triangle(prim_index);
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const float3 *verts = &mesh->verts[0];
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float3 v1 = tfm ? transform_point(tfm, verts[t.v[2]]) : verts[t.v[2]];
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v1 = get_unaligned_point(v1);
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for(int i = 0; i < 3; i++) {
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float3 v0 = v1;
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int vindex = t.v[i];
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v1 = tfm ? transform_point(tfm, verts[vindex]) : verts[vindex];
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v1 = get_unaligned_point(v1);
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float v0p = v0[dim];
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float v1p = v1[dim];
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/* insert vertex to the boxes it belongs to. */
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if(v0p <= pos)
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left_bounds.grow(v0);
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if(v0p >= pos)
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right_bounds.grow(v0);
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/* edge intersects the plane => insert intersection to both boxes. */
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if((v0p < pos && v1p > pos) || (v0p > pos && v1p < pos)) {
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float3 t = lerp(v0, v1, clamp((pos - v0p) / (v1p - v0p), 0.0f, 1.0f));
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left_bounds.grow(t);
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right_bounds.grow(t);
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}
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}
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}
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void BVHSpatialSplit::split_curve_primitive(const Mesh *mesh,
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const Transform *tfm,
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int prim_index,
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int segment_index,
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int dim,
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float pos,
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BoundBox& left_bounds,
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BoundBox& right_bounds)
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{
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/* curve split: NOTE - Currently ignores curve width and needs to be fixed.*/
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Mesh::Curve curve = mesh->get_curve(prim_index);
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const int k0 = curve.first_key + segment_index;
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const int k1 = k0 + 1;
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float3 v0 = mesh->curve_keys[k0];
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float3 v1 = mesh->curve_keys[k1];
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if(tfm != NULL) {
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v0 = transform_point(tfm, v0);
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v1 = transform_point(tfm, v1);
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}
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v0 = get_unaligned_point(v0);
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v1 = get_unaligned_point(v1);
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float v0p = v0[dim];
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float v1p = v1[dim];
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/* insert vertex to the boxes it belongs to. */
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if(v0p <= pos)
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left_bounds.grow(v0);
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if(v0p >= pos)
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right_bounds.grow(v0);
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if(v1p <= pos)
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left_bounds.grow(v1);
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if(v1p >= pos)
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right_bounds.grow(v1);
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/* edge intersects the plane => insert intersection to both boxes. */
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if((v0p < pos && v1p > pos) || (v0p > pos && v1p < pos)) {
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float3 t = lerp(v0, v1, clamp((pos - v0p) / (v1p - v0p), 0.0f, 1.0f));
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left_bounds.grow(t);
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right_bounds.grow(t);
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}
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}
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void BVHSpatialSplit::split_triangle_reference(const BVHReference& ref,
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const Mesh *mesh,
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int dim,
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float pos,
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BoundBox& left_bounds,
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BoundBox& right_bounds)
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{
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split_triangle_primitive(mesh,
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NULL,
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ref.prim_index(),
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dim,
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pos,
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left_bounds,
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right_bounds);
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}
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void BVHSpatialSplit::split_curve_reference(const BVHReference& ref,
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const Mesh *mesh,
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int dim,
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float pos,
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BoundBox& left_bounds,
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BoundBox& right_bounds)
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{
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split_curve_primitive(mesh,
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NULL,
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ref.prim_index(),
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PRIMITIVE_UNPACK_SEGMENT(ref.prim_type()),
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dim,
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pos,
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left_bounds,
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right_bounds);
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}
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void BVHSpatialSplit::split_object_reference(const Object *object,
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int dim,
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float pos,
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BoundBox& left_bounds,
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BoundBox& right_bounds)
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{
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Mesh *mesh = object->mesh;
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for(int tri_idx = 0; tri_idx < mesh->num_triangles(); ++tri_idx) {
|
|
split_triangle_primitive(mesh,
|
|
&object->tfm,
|
|
tri_idx,
|
|
dim,
|
|
pos,
|
|
left_bounds,
|
|
right_bounds);
|
|
}
|
|
for(int curve_idx = 0; curve_idx < mesh->num_curves(); ++curve_idx) {
|
|
Mesh::Curve curve = mesh->get_curve(curve_idx);
|
|
for(int segment_idx = 0;
|
|
segment_idx < curve.num_keys - 1;
|
|
++segment_idx)
|
|
{
|
|
split_curve_primitive(mesh,
|
|
&object->tfm,
|
|
curve_idx,
|
|
segment_idx,
|
|
dim,
|
|
pos,
|
|
left_bounds,
|
|
right_bounds);
|
|
}
|
|
}
|
|
}
|
|
|
|
void BVHSpatialSplit::split_reference(const BVHBuild& builder,
|
|
BVHReference& left,
|
|
BVHReference& right,
|
|
const BVHReference& ref,
|
|
int dim,
|
|
float pos)
|
|
{
|
|
/* initialize boundboxes */
|
|
BoundBox left_bounds = BoundBox::empty;
|
|
BoundBox right_bounds = BoundBox::empty;
|
|
|
|
/* loop over vertices/edges. */
|
|
const Object *ob = builder.objects[ref.prim_object()];
|
|
const Mesh *mesh = ob->mesh;
|
|
|
|
if(ref.prim_type() & PRIMITIVE_ALL_TRIANGLE) {
|
|
split_triangle_reference(ref,
|
|
mesh,
|
|
dim,
|
|
pos,
|
|
left_bounds,
|
|
right_bounds);
|
|
}
|
|
else if(ref.prim_type() & PRIMITIVE_ALL_CURVE) {
|
|
split_curve_reference(ref,
|
|
mesh,
|
|
dim,
|
|
pos,
|
|
left_bounds,
|
|
right_bounds);
|
|
}
|
|
else {
|
|
split_object_reference(ob,
|
|
dim,
|
|
pos,
|
|
left_bounds,
|
|
right_bounds);
|
|
}
|
|
|
|
/* intersect with original bounds. */
|
|
left_bounds.max[dim] = pos;
|
|
right_bounds.min[dim] = pos;
|
|
|
|
left_bounds.intersect(ref.bounds());
|
|
right_bounds.intersect(ref.bounds());
|
|
|
|
/* set references */
|
|
left = BVHReference(left_bounds, ref.prim_index(), ref.prim_object(), ref.prim_type());
|
|
right = BVHReference(right_bounds, ref.prim_index(), ref.prim_object(), ref.prim_type());
|
|
}
|
|
|
|
CCL_NAMESPACE_END
|