1 files changed, 293 insertions, 0 deletions
diff --git a/intern/cycles/bvh/bvh_split.cpp b/intern/cycles/bvh/bvh_split.cpp
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+++ b/intern/cycles/bvh/bvh_split.cpp
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+/*
+ * Adapted from code copyright 2009-2010 NVIDIA Corporation
+ * Modifications Copyright 2011, 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.
+ */
+
+#include "bvh_build.h"
+#include "bvh_split.h"
+#include "bvh_sort.h"
+
+#include "mesh.h"
+#include "object.h"
+
+#include "util_algorithm.h"
+
+CCL_NAMESPACE_BEGIN
+
+/* Object Split */
+
+BVHObjectSplit::BVHObjectSplit(BVHBuild *builder, const BVHRange& range, float nodeSAH)
+: sah(FLT_MAX), dim(0), num_left(0), left_bounds(BoundBox::empty), right_bounds(BoundBox::empty)
+{
+	const BVHReference *ref_ptr = &builder->references[range.start()];
+	float min_sah = FLT_MAX;
+
+	for(int dim = 0; dim < 3; dim++) {
+		/* sort references */
+		bvh_reference_sort(range.start(), range.end(), &builder->references[0], dim);
+
+		/* sweep right to left and determine bounds. */
+		BoundBox right_bounds = BoundBox::empty;
+
+		for(int i = range.size() - 1; i > 0; i--) {
+			right_bounds.grow(ref_ptr[i].bounds());
+			builder->spatial_right_bounds[i - 1] = right_bounds;
+		}
+
+		/* sweep left to right and select lowest SAH. */
+		BoundBox left_bounds = BoundBox::empty;
+
+		for(int i = 1; i < range.size(); i++) {
+			left_bounds.grow(ref_ptr[i - 1].bounds());
+			right_bounds = builder->spatial_right_bounds[i - 1];
+
+			float sah = nodeSAH +
+				left_bounds.safe_area() * builder->params.triangle_cost(i) +
+				right_bounds.safe_area() * builder->params.triangle_cost(range.size() - i);
+
+			if(sah < min_sah) {
+				min_sah = sah;
+
+				this->sah = sah;
+				this->dim = dim;
+				this->num_left = i;
+				this->left_bounds = left_bounds;
+				this->right_bounds = right_bounds;
+			}
+		}
+	}
+}
+
+void BVHObjectSplit::split(BVHBuild *builder, BVHRange& left, BVHRange& right, const BVHRange& range)
+{
+	/* sort references according to split */
+	bvh_reference_sort(range.start(), range.end(), &builder->references[0], this->dim);
+
+	/* split node ranges */
+	left = BVHRange(this->left_bounds, range.start(), this->num_left);
+	right = BVHRange(this->right_bounds, left.end(), range.size() - this->num_left);
+
+}
+
+/* Spatial Split */
+
+BVHSpatialSplit::BVHSpatialSplit(BVHBuild *builder, const BVHRange& range, float nodeSAH)
+: sah(FLT_MAX), dim(0), pos(0.0f)
+{
+	/* initialize bins. */
+	float3 origin = range.bounds().min;
+	float3 binSize = (range.bounds().max - origin) * (1.0f / (float)BVHParams::NUM_SPATIAL_BINS);
+	float3 invBinSize = 1.0f / binSize;
+
+	for(int dim = 0; dim < 3; dim++) {
+		for(int i = 0; i < BVHParams::NUM_SPATIAL_BINS; i++) {
+			BVHSpatialBin& bin = builder->spatial_bins[dim][i];
+
+			bin.bounds = BoundBox::empty;
+			bin.enter = 0;
+			bin.exit = 0;
+		}
+	}
+
+	/* chop references into bins. */
+	for(unsigned int refIdx = range.start(); refIdx < range.end(); refIdx++) {
+		const BVHReference& ref = builder->references[refIdx];
+		float3 firstBinf = (ref.bounds().min - origin) * invBinSize;
+		float3 lastBinf = (ref.bounds().max - origin) * invBinSize;
+		int3 firstBin = make_int3((int)firstBinf.x, (int)firstBinf.y, (int)firstBinf.z);
+		int3 lastBin = make_int3((int)lastBinf.x, (int)lastBinf.y, (int)lastBinf.z);
+
+		firstBin = clamp(firstBin, 0, BVHParams::NUM_SPATIAL_BINS - 1);
+		lastBin = clamp(lastBin, firstBin, BVHParams::NUM_SPATIAL_BINS - 1);
+
+		for(int dim = 0; dim < 3; dim++) {
+			BVHReference currRef = ref;
+
+			for(int i = firstBin[dim]; i < lastBin[dim]; i++) {
+				BVHReference leftRef, rightRef;
+
+				split_reference(builder, leftRef, rightRef, currRef, dim, origin[dim] + binSize[dim] * (float)(i + 1));
+				builder->spatial_bins[dim][i].bounds.grow(leftRef.bounds());
+				currRef = rightRef;
+			}
+
+			builder->spatial_bins[dim][lastBin[dim]].bounds.grow(currRef.bounds());
+			builder->spatial_bins[dim][firstBin[dim]].enter++;
+			builder->spatial_bins[dim][lastBin[dim]].exit++;
+		}
+	}
+
+	/* select best split plane. */
+	for(int dim = 0; dim < 3; dim++) {
+		/* sweep right to left and determine bounds. */
+		BoundBox right_bounds = BoundBox::empty;
+
+		for(int i = BVHParams::NUM_SPATIAL_BINS - 1; i > 0; i--) {
+			right_bounds.grow(builder->spatial_bins[dim][i].bounds);
+			builder->spatial_right_bounds[i - 1] = right_bounds;
+		}
+
+		/* sweep left to right and select lowest SAH. */
+		BoundBox left_bounds = BoundBox::empty;
+		int leftNum = 0;
+		int rightNum = range.size();
+
+		for(int i = 1; i < BVHParams::NUM_SPATIAL_BINS; i++) {
+			left_bounds.grow(builder->spatial_bins[dim][i - 1].bounds);
+			leftNum += builder->spatial_bins[dim][i - 1].enter;
+			rightNum -= builder->spatial_bins[dim][i - 1].exit;
+
+			float sah = nodeSAH +
+				left_bounds.safe_area() * builder->params.triangle_cost(leftNum) +
+				builder->spatial_right_bounds[i - 1].safe_area() * builder->params.triangle_cost(rightNum);
+
+			if(sah < this->sah) {
+				this->sah = sah;
+				this->dim = dim;
+				this->pos = origin[dim] + binSize[dim] * (float)i;
+			}
+		}
+	}
+}
+
+void BVHSpatialSplit::split(BVHBuild *builder, BVHRange& left, BVHRange& right, const BVHRange& range)
+{
+	/* Categorize references and compute bounds.
+	 *
+	 * Left-hand side:			[left_start, left_end[
+	 * Uncategorized/split:		[left_end, right_start[
+	 * Right-hand side:			[right_start, refs.size()[ */
+
+	vector<BVHReference>& refs = builder->references;
+	int left_start = range.start();
+	int left_end = left_start;
+	int right_start = range.end();
+	int right_end = range.end();
+	BoundBox left_bounds = BoundBox::empty;
+	BoundBox right_bounds = BoundBox::empty;
+
+	for(int i = left_end; i < right_start; i++) {
+		if(refs[i].bounds().max[this->dim] <= this->pos) {
+			/* entirely on the left-hand side */
+			left_bounds.grow(refs[i].bounds());
+			swap(refs[i], refs[left_end++]);
+		}
+		else if(refs[i].bounds().min[this->dim] >= this->pos) {
+			/* entirely on the right-hand side */
+			right_bounds.grow(refs[i].bounds());
+			swap(refs[i--], refs[--right_start]);
+		}
+	}
+
+	/* duplicate or unsplit references intersecting both sides. */
+	while(left_end < right_start) {
+		/* split reference. */
+		BVHReference lref, rref;
+
+		split_reference(builder, lref, rref, refs[left_end], this->dim, this->pos);
+
+		/* compute SAH for duplicate/unsplit candidates. */
+		BoundBox lub = left_bounds;		// Unsplit to left:		new left-hand bounds.
+		BoundBox rub = right_bounds;	// Unsplit to right:	new right-hand bounds.
+		BoundBox ldb = left_bounds;		// Duplicate:			new left-hand bounds.
+		BoundBox rdb = right_bounds;	// Duplicate:			new right-hand bounds.
+
+		lub.grow(refs[left_end].bounds());
+		rub.grow(refs[left_end].bounds());
+		ldb.grow(lref.bounds());
+		rdb.grow(rref.bounds());
+
+		float lac = builder->params.triangle_cost(left_end - left_start);
+		float rac = builder->params.triangle_cost(right_end - right_start);
+		float lbc = builder->params.triangle_cost(left_end - left_start + 1);
+		float rbc = builder->params.triangle_cost(right_end - right_start + 1);
+
+		float unsplitLeftSAH = lub.safe_area() * lbc + right_bounds.safe_area() * rac;
+		float unsplitRightSAH = left_bounds.safe_area() * lac + rub.safe_area() * rbc;
+		float duplicateSAH = ldb.safe_area() * lbc + rdb.safe_area() * rbc;
+		float minSAH = min(min(unsplitLeftSAH, unsplitRightSAH), duplicateSAH);
+
+		if(minSAH == unsplitLeftSAH) {
+			/* unsplit to left */
+			left_bounds = lub;
+			left_end++;
+		}
+		else if(minSAH == unsplitRightSAH) {
+			/* unsplit to right */
+			right_bounds = rub;
+			swap(refs[left_end], refs[--right_start]);
+		}
+		else {
+			/* duplicate */
+			left_bounds = ldb;
+			right_bounds = rdb;
+			refs[left_end++] = lref;
+			refs.insert(refs.begin() + right_end, rref);
+			right_end++;
+		}
+	}
+
+	left = BVHRange(left_bounds, left_start, left_end - left_start);
+	right = BVHRange(right_bounds, right_start, right_end - right_start);
+}
+
+void BVHSpatialSplit::split_reference(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. */
+	Object *ob = builder->objects[ref.prim_object()];
+	const Mesh *mesh = ob->mesh;
+	const int *inds = mesh->triangles[ref.prim_index()].v;
+	const float3 *verts = &mesh->verts[0];
+	const float3* v1 = &verts[inds[2]];
+
+	for(int i = 0; i < 3; i++) {
+		const float3* v0 = v1;
+		int vindex = inds[i];
+		v1 = &verts[vindex];
+		float v0p = (*v0)[dim];
+		float v1p = (*v1)[dim];
+
+		/* insert vertex to the boxes it belongs to. */
+		if(v0p <= pos)
+			left_bounds.grow(*v0);
+
+		if(v0p >= pos)
+			right_bounds.grow(*v0);
+
+		/* edge intersects the plane => insert intersection to both boxes. */
+		if((v0p < pos && v1p > pos) || (v0p > pos && v1p < pos)) {
+			float3 t = lerp(*v0, *v1, clamp((pos - v0p) / (v1p - v0p), 0.0f, 1.0f));
+			left_bounds.grow(t);
+			right_bounds.grow(t);
+		}
+	}
+
+	/* 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 referecnes */
+	left = BVHReference(left_bounds, ref.prim_index(), ref.prim_object());
+	right = BVHReference(right_bounds, ref.prim_index(), ref.prim_object());
+}
+
+CCL_NAMESPACE_END
+