private Node BuildSubTree(RenderableCollection primitives, int start, int end)
{
if (start - end == 0)
return null;
AABB bound = primitives.GetRange(start, end - start).Select(prim => prim.WorldBound(sceneVertices)).Aggregate((b1, b2) => b1.Union(b2));
var node = new Node() { Bound = bound, SplitAxis = (Axis)bound.MaximumExtent() };
bvhNodesCount++;
if ((end - start) <= PrimitivesInNode)
{
node.StartOffset = start;
node.nPrims = end - start;
//node.Primitives = primitives.GetRange(start, (end - start));
return node;
}
//float pmid;
int axis = bound.MaximumExtent();
Comparison<Triangle> tc = (t1, t2) => CompareTriangles(t1, t2, (Axis)bound.MaximumExtent());
primitives.PartialSort(tc, start, end);
//FindBestSplit(primitives, start, end, out pmid, out axis);
//var pmid = .5f * (bound.Min[axis] + bound.Max[axis]);
//FindBestSplit(primitives.GetRange(start, end-start), start, end, out pmid, out axis);
//var cmp = new MidComparer() { dim = axis, pMid = pmid, vertices = sceneVertices};
node.SplitAxis = (Axis)axis;
var mid =
//start+Algorithms.Partition(primitives.GetRange(start, end - start), cmp.Compare);
(start + end) / 2;
node.Left = this.BuildSubTree(primitives, start, mid);
node.Right = this.BuildSubTree(primitives, mid, end);
return node;
}
