void BVH4BuilderFast::recurseSAH(BuildRecord& current, Allocator& nodeAlloc, Allocator& leafAlloc, const size_t mode, const size_t threadID, const size_t numThreads)
{
__aligned(64) BuildRecord children[BVH4::N];
/* create leaf node */
if (current.depth >= BVH4::maxBuildDepth || current.isLeaf()) {
assert(mode != BUILD_TOP_LEVEL);
createLeaf(current,nodeAlloc,leafAlloc,threadID,numThreads);
return;
}
/* fill all 4 children by always splitting the one with the largest surface area */
unsigned int numChildren = 1;
children[0] = current;
do {
/* find best child with largest bounding box area */
int bestChild = -1;
float bestArea = neg_inf;
for (unsigned int i=0; i<numChildren; i++)
{
/* ignore leaves as they cannot get split */
if (children[i].isLeaf())
continue;
/* remember child with largest area */
if (children[i].sceneArea() > bestArea) {
bestArea = children[i].sceneArea();
bestChild = i;
}
}
if (bestChild == -1) break;
/*! split best child into left and right child */
__aligned(64) BuildRecord left, right;
if (!split(children[bestChild],left,right,mode,threadID,numThreads))
continue;
/* add new children left and right */
left.depth = right.depth = current.depth+1;
children[bestChild] = children[numChildren-1];
children[numChildren-1] = left;
children[numChildren+0] = right;
numChildren++;
} while (numChildren < BVH4::N);
/* create leaf node if no split is possible */
if (numChildren == 1) {
assert(mode != BUILD_TOP_LEVEL);
createLeaf(current,nodeAlloc,leafAlloc,threadID,numThreads);
return;
}
/* allocate node */
Node* node = (Node*) nodeAlloc.malloc(sizeof(Node)); node->clear();
*(NodeRef*)current.parentNode = bvh->encodeNode(node);
/* recurse into each child */
for (unsigned int i=0; i<numChildren; i++)
{
node->set(i,children[i].bounds.geometry);
children[i].parentNode = (size_t)&node->child(i);
children[i].depth = current.depth+1;
recurse(children[i],nodeAlloc,leafAlloc,mode,threadID,numThreads);
}
}
