private void Subdivide(BVHNode[] leafs, int leafCount, int addNext)
{
if (leafCount == 1)
{
_nodes[addNext] = leafs.First();
return;
}
var bounds = leafs.Aggregate(Nothing, (cur, n) => BoundingBox.Merge(cur, n.Bounds));
var comparer = new AxisBVHNodeComparer(bounds.Maximum - bounds.Minimum);
Array.Sort(leafs, comparer);
_nodes[addNext++] = BVHNode.CreateBranch(ChildCountFor(leafCount), ref bounds);
var leftCount = leafCount / 2;
var rightCount = leafCount - leftCount;
if (leafCount >= MinimumLeafCountForParallelism)
{
Parallel.Invoke(_parallelOptions,
() => Subdivide(leafs.Take(leftCount).ToArray(), leftCount, addNext),
() => Subdivide(leafs.Skip(leftCount).ToArray(), rightCount, addNext + ChildCountFor(leftCount)));
}
else
{
Subdivide(leafs.Take(leftCount).ToArray(), leftCount, addNext);
Subdivide(leafs.Skip(leftCount).ToArray(), rightCount, addNext + ChildCountFor(leftCount));
}
}
private static BVHNode[] ReduceToBVHNodes(IEnumerable <SceneObject> scene)
{
return(scene
.SelectMany(s => s.Geometry.Triangles
.Select((t, i) =>
{
var bounds = t.BoundsIn(s.Geometry.Vertices);
return BVHNode.CreateLeaf(s, i, ref bounds);
}))
.ToArray());
}