Cycles: merging features from tomato branch.

=== BVH build time optimizations ===

* BVH building was multithreaded. Not all building is multithreaded, packing
  and the initial bounding/splitting is still single threaded, but recursive
  splitting is, which was the main bottleneck.

* Object splitting now uses binning rather than sorting of all elements, using
  code from the Embree raytracer from Intel.
  http://software.intel.com/en-us/articles/embree-photo-realistic-ray-tracing-kernels/

* Other small changes to avoid allocations, pack memory more tightly, avoid
  some unnecessary operations, ...

These optimizations do not work yet when Spatial Splits are enabled, for that
more work is needed. There's also other optimizations still needed, in
particular for the case of many low poly objects, the packing step and node
memory allocation.

BVH raytracing time should remain about the same, but BVH build time should be
significantly reduced, test here show speedup of about 5x to 10x on a dual core
and 5x to 25x on an 8-core machine, depending on the scene.

=== Threads ===

Centralized task scheduler for multithreading, which is basically the
CPU device threading code wrapped into something reusable.

Basic idea is that there is a single TaskScheduler that keeps a pool of threads,
one for each core. Other places in the code can then create a TaskPool that they
can drop Tasks in to be executed by the scheduler, and wait for them to complete
or cancel them early.

=== Normal ====

Added a Normal output to the texture coordinate node. This currently
gives the object space normal, which is the same under object animation.

In the future this might become a "generated" normal so it's also stable for
deforming objects, but for now it's already useful for non-deforming objects.

=== Render Layers ===

Per render layer Samples control, leaving it to 0 will use the common scene
setting.

Environment pass will now render environment even if film is set to transparent.

Exclude Layers" added. Scene layers (all object that influence the render,
directly or indirectly) are shared between all render layers. However sometimes
it's useful to leave out some object influence for a particular render layer.
That's what this option allows you to do.

=== Filter Glossy ===

When using a value higher than 0.0, this will blur glossy reflections after
blurry bounces, to reduce noise at the cost of accuracy. 1.0 is a good
starting value to tweak.

Some light paths have a low probability of being found while contributing much
light to the pixel. As a result these light paths will be found in some pixels
and not in others, causing fireflies. An example of such a difficult path might
be a small light that is causing a small specular highlight on a sharp glossy
material, which we are seeing through a rough glossy material. With path tracing
it is difficult to find the specular highlight, but if we increase the roughness
on the material the highlight gets bigger and softer, and so easier to find.

Often this blurring will be hardly noticeable, because we are seeing it through
a blurry material anyway, but there are also cases where this will lead to a
loss of detail in lighting.

1 files changed, 110 insertions, 0 deletions

diff --git a/intern/cycles/bvh/bvh_split.h b/intern/cycles/bvh/bvh_split.h
new file mode 100644
index 00000000000..1f4befbe8e2
--- /dev/null
+++ b/intern/cycles/bvh/bvh_split.h
@@ -0,0 +1,110 @@
+/*
+ * 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.
+ */
+
+#ifndef __BVH_SPLIT_H__
+#define __BVH_SPLIT_H__
+
+#include "bvh_build.h"
+#include "bvh_params.h"
+
+CCL_NAMESPACE_BEGIN
+
+class BVHBuild;
+
+/* Object Split */
+
+class BVHObjectSplit
+{
+public:
+	float sah;
+	int dim;
+	int num_left;
+	BoundBox left_bounds;
+	BoundBox right_bounds;
+
+	BVHObjectSplit() {}
+	BVHObjectSplit(BVHBuild *builder, const BVHRange& range, float nodeSAH);
+
+	void split(BVHBuild *builder, BVHRange& left, BVHRange& right, const BVHRange& range);
+};
+
+/* Spatial Split */
+
+class BVHSpatialSplit
+{
+public:
+	float sah;
+	int dim;
+	float pos;
+
+	BVHSpatialSplit() : sah(FLT_MAX), dim(0), pos(0.0f) {}
+	BVHSpatialSplit(BVHBuild *builder, const BVHRange& range, float nodeSAH);
+
+	void split(BVHBuild *builder, BVHRange& left, BVHRange& right, const BVHRange& range);
+	void split_reference(BVHBuild *builder, BVHReference& left, BVHReference& right, const BVHReference& ref, int dim, float pos);
+};
+
+/* Mixed Object-Spatial Split */
+
+class BVHMixedSplit
+{
+public:
+	BVHObjectSplit object;
+	BVHSpatialSplit spatial;
+
+	float leafSAH;
+	float nodeSAH;
+	float minSAH;
+
+	bool no_split;
+
+	__forceinline BVHMixedSplit(BVHBuild *builder, const BVHRange& range, int level)
+	{
+		/* find split candidates. */
+		float area = range.bounds().safe_area();
+
+		leafSAH = area * builder->params.triangle_cost(range.size());
+		nodeSAH = area * builder->params.node_cost(2);
+
+		object = BVHObjectSplit(builder, range, nodeSAH);
+
+		if(builder->params.use_spatial_split && level < BVHParams::MAX_SPATIAL_DEPTH) {
+			BoundBox overlap = object.left_bounds;
+			overlap.intersect(object.right_bounds);
+
+			if(overlap.safe_area() >= builder->spatial_min_overlap)
+				spatial = BVHSpatialSplit(builder, range, nodeSAH);
+		}
+
+		/* leaf SAH is the lowest => create leaf. */
+		minSAH = min(min(leafSAH, object.sah), spatial.sah);
+		no_split = (minSAH == leafSAH && range.size() <= builder->params.max_leaf_size);
+	}
+
+	__forceinline void split(BVHBuild *builder, BVHRange& left, BVHRange& right, const BVHRange& range)
+	{
+		if(builder->params.use_spatial_split && minSAH == spatial.sah)
+			spatial.split(builder, left, right, range);
+		if(!left.size() || !right.size())
+			object.split(builder, left, right, range);
+	}
+};
+
+CCL_NAMESPACE_END
+
+#endif /* __BVH_SPLIT_H__ */
+