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.
116 lines
3.4 KiB
C++
116 lines
3.4 KiB
C++
/*
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* Adapted from code copyright 2009-2011 Intel Corporation
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* Modifications Copyright 2012, 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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#ifndef __BVH_BINNING_H__
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#define __BVH_BINNING_H__
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#include "bvh_params.h"
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#include "bvh_unaligned.h"
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#include "util_types.h"
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CCL_NAMESPACE_BEGIN
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class BVHBuild;
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/* Single threaded object binner. Finds the split with the best SAH heuristic
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* by testing for each dimension multiple partitionings for regular spaced
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* partition locations. A partitioning for a partition location is computed,
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* by putting primitives whose centroid is on the left and right of the split
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* location to different sets. The SAH is evaluated by computing the number of
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* blocks occupied by the primitives in the partitions. */
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class BVHObjectBinning : public BVHRange
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{
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public:
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__forceinline BVHObjectBinning() : leafSAH(FLT_MAX) {}
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BVHObjectBinning(const BVHRange& job,
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BVHReference *prims,
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const BVHUnaligned *unaligned_heuristic = NULL,
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const Transform *aligned_space = NULL);
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void split(BVHReference *prims,
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BVHObjectBinning& left_o,
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BVHObjectBinning& right_o) const;
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__forceinline const BoundBox& unaligned_bounds() { return bounds_; }
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float splitSAH; /* SAH cost of the best split */
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float leafSAH; /* SAH cost of creating a leaf */
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protected:
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int dim; /* best split dimension */
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int pos; /* best split position */
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size_t num_bins; /* actual number of bins to use */
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float3 scale; /* scaling factor to compute bin */
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/* Effective bounds and centroid bounds. */
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BoundBox bounds_;
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BoundBox cent_bounds_;
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const BVHUnaligned *unaligned_heuristic_;
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const Transform *aligned_space_;
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enum { MAX_BINS = 32 };
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enum { LOG_BLOCK_SIZE = 2 };
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/* computes the bin numbers for each dimension for a box. */
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__forceinline int4 get_bin(const BoundBox& box) const
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{
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int4 a = make_int4((box.center2() - cent_bounds_.min)*scale - make_float3(0.5f));
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int4 mn = make_int4(0);
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int4 mx = make_int4((int)num_bins-1);
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return clamp(a, mn, mx);
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}
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/* computes the bin numbers for each dimension for a point. */
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__forceinline int4 get_bin(const float3& c) const
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{
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return make_int4((c - cent_bounds_.min)*scale - make_float3(0.5f));
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}
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/* compute the number of blocks occupied for each dimension. */
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__forceinline float4 blocks(const int4& a) const
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{
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return make_float4((a + make_int4((1 << LOG_BLOCK_SIZE)-1)) >> LOG_BLOCK_SIZE);
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}
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/* compute the number of blocks occupied in one dimension. */
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__forceinline int blocks(size_t a) const
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{
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return (int)((a+((1LL << LOG_BLOCK_SIZE)-1)) >> LOG_BLOCK_SIZE);
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}
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__forceinline BoundBox get_prim_bounds(const BVHReference& prim) const
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{
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if(aligned_space_ == NULL) {
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return prim.bounds();
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}
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else {
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return unaligned_heuristic_->compute_aligned_prim_boundbox(
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prim, *aligned_space_);
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}
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}
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};
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CCL_NAMESPACE_END
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#endif
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