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, 70 insertions, 0 deletions

diff --git a/intern/cycles/bvh/bvh_node.cpp b/intern/cycles/bvh/bvh_node.cpp
index 8294690da7d..f5cd699bdf4 100644
--- a/intern/cycles/bvh/bvh_node.cpp
+++ b/intern/cycles/bvh/bvh_node.cpp
@@ -61,6 +61,76 @@ int BVHNode::getSubtreeSize(BVH_STAT stat) const
 				}
 			}
 			return cnt;
+		case BVH_STAT_ALIGNED_COUNT:
+			if(!is_unaligned()) {
+				cnt = 1;
+			}
+			break;
+		case BVH_STAT_UNALIGNED_COUNT:
+			if(is_unaligned()) {
+				cnt = 1;
+			}
+			break;
+		case BVH_STAT_ALIGNED_INNER_COUNT:
+			if(!is_leaf()) {
+				bool has_unaligned = false;
+				for(int j = 0; j < num_children(); j++) {
+					has_unaligned |= get_child(j)->is_unaligned();
+				}
+				cnt += has_unaligned? 0: 1;
+			}
+			break;
+		case BVH_STAT_UNALIGNED_INNER_COUNT:
+			if(!is_leaf()) {
+				bool has_unaligned = false;
+				for(int j = 0; j < num_children(); j++) {
+					has_unaligned |= get_child(j)->is_unaligned();
+				}
+				cnt += has_unaligned? 1: 0;
+			}
+			break;
+		case BVH_STAT_ALIGNED_INNER_QNODE_COUNT:
+			{
+				bool has_unaligned = false;
+				for(int i = 0; i < num_children(); i++) {
+					BVHNode *node = get_child(i);
+					if(node->is_leaf()) {
+						has_unaligned |= node->is_unaligned();
+					}
+					else {
+						for(int j = 0; j < node->num_children(); j++) {
+							cnt += node->get_child(j)->getSubtreeSize(stat);
+							has_unaligned |= node->get_child(j)->is_unaligned();
+						}
+					}
+				}
+				cnt += has_unaligned? 0: 1;
+			}
+			return cnt;
+		case BVH_STAT_UNALIGNED_INNER_QNODE_COUNT:
+			{
+				bool has_unaligned = false;
+				for(int i = 0; i < num_children(); i++) {
+					BVHNode *node = get_child(i);
+					if(node->is_leaf()) {
+						has_unaligned |= node->is_unaligned();
+					}
+					else {
+						for(int j = 0; j < node->num_children(); j++) {
+							cnt += node->get_child(j)->getSubtreeSize(stat);
+							has_unaligned |= node->get_child(j)->is_unaligned();
+						}
+					}
+				}
+				cnt += has_unaligned? 1: 0;
+			}
+			return cnt;
+		case BVH_STAT_ALIGNED_LEAF_COUNT:
+			cnt = (is_leaf() && !is_unaligned()) ? 1 : 0;
+			break;
+		case BVH_STAT_UNALIGNED_LEAF_COUNT:
+			cnt = (is_leaf() && is_unaligned()) ? 1 : 0;
+			break;
 		default:
 			assert(0); /* unknown mode */
 	}