BVHBuildNode *BVH::recursiveBuild(int start, int end, int *numTotalNodes)
{
AABoundingBox bbox;
for(int i=start; i<end; i++){
bbox.join(m_buildData[i].m_bbox);
}
BVHBuildNode *node = new BVHBuildNode();
(*numTotalNodes)++;
int numTriangles = end - start;
if(numTriangles == 1){
createLeafNode(start,end,bbox,node, numTotalNodes);
}
else{
AABoundingBox bboxCentroids;
for(int i=start; i<end; i++){
bboxCentroids.join(m_buildData[i].m_centroid);
}
int dim = bboxCentroids.getMaximumExtent();
if(bboxCentroids.min(dim) == bboxCentroids.max(dim)){
createLeafNode(start,end,bbox,node,numTotalNodes);
}
else{
float splitCost;
int splitBucket;
findSAHSplit(dim,start,end,bboxCentroids,bbox, &splitCost, &splitBucket);
if(numTriangles > 6 || splitCost < numTriangles){
BVHTriangleInfo *midPtr = std::partition(&m_buildData[start], &m_buildData[end], CompareToBucket(dim, splitBucket, 12, bboxCentroids));
int mid = midPtr - &m_buildData[0];
if(mid == start || mid == end){
mid = start+1;
}
node->initInterior(dim, recursiveBuild(start,mid,numTotalNodes), recursiveBuild(mid,end,numTotalNodes));
}
else{
createLeafNode(start,end,bbox,node,numTotalNodes);
}
}
}
return node;
}
