When do we make node a leaf? Is it when there is only one primitive or some other cases too?

@alpaca In slide 30 there is a formula for calculating the cost of splitting a node into two children. If the cost of splitting the current node is less than traversing the current node as a leaf, we will stop splitting and make it a leaf.

I think this algorithm could become really slow when we have many triangles with different coordinates right? Can we just randomly shoot rays and then cluster the triangles based on how many similar rays do they encounter during simulation?

I think randomly shooting rays brings up the question of, what rays do we actually expect to see and whether the simulation is robust enough.