Cycles: Implement unaligned nodes BVH builder

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.

1 files changed, 16 insertions, 11 deletions

diff --git a/intern/cycles/bvh/bvh_build.h b/intern/cycles/bvh/bvh_build.h
index a015b89d72f..64180349935 100644
--- a/intern/cycles/bvh/bvh_build.h
+++ b/intern/cycles/bvh/bvh_build.h
@@ -22,6 +22,7 @@
 
 #include "bvh.h"
 #include "bvh_binning.h"
+#include "bvh_unaligned.h"
 
 #include "util_boundbox.h"
 #include "util_task.h"
@@ -59,13 +60,14 @@ protected:
 	friend class BVHSpatialSplit;
 	friend class BVHBuildTask;
 	friend class BVHSpatialSplitBuildTask;
+	friend class BVHObjectBinning;
 
-	/* adding references */
+	/* Adding references. */
 	void add_reference_mesh(BoundBox& root, BoundBox& center, Mesh *mesh, int i);
 	void add_reference_object(BoundBox& root, BoundBox& center, Object *ob, int i);
 	void add_references(BVHRange& root);
 
-	/* building */
+	/* Building. */
 	BVHNode *build_node(const BVHRange& range,
 	                    vector<BVHReference> *references,
 	                    int level,
@@ -78,7 +80,7 @@ protected:
 	bool range_within_max_leaf_size(const BVHRange& range,
 	                                const vector<BVHReference>& references) const;
 
-	/* threads */
+	/* Threads. */
 	enum { THREAD_TASK_SIZE = 4096 };
 	void thread_build_node(InnerNode *node,
 	                       int child,
@@ -92,41 +94,44 @@ protected:
 	                                     int thread_id);
 	thread_mutex build_mutex;
 
-	/* progress */
+	/* Progress. */
 	void progress_update();
 
-	/* tree rotations */
+	/* Tree rotations. */
 	void rotate(BVHNode *node, int max_depth);
 	void rotate(BVHNode *node, int max_depth, int iterations);
 
-	/* objects and primitive references */
+	/* Objects and primitive references. */
 	vector<Object*> objects;
 	vector<BVHReference> references;
 	int num_original_references;
 
-	/* output primitive indexes and objects */
+	/* Output primitive indexes and objects. */
 	array<int>& prim_type;
 	array<int>& prim_index;
 	array<int>& prim_object;
 
-	/* build parameters */
+	/* Build parameters. */
 	BVHParams params;
 
-	/* progress reporting */
+	/* Progress reporting. */
 	Progress& progress;
 	double progress_start_time;
 	size_t progress_count;
 	size_t progress_total;
 	size_t progress_original_total;
 
-	/* spatial splitting */
+	/* Spatial splitting. */
 	float spatial_min_overlap;
 	vector<BVHSpatialStorage> spatial_storage;
 	size_t spatial_free_index;
 	thread_spin_lock spatial_spin_lock;
 
-	/* threads */
+	/* Threads. */
 	TaskPool task_pool;
+
+	/* Unaligned building. */
+	BVHUnaligned unaligned_heuristic;
 };
 
 CCL_NAMESPACE_END