Trying to implement BSP - any advice? (Solved)

[nemyax]

I ended up with this:

Code:

walk([], Order, [], Data) -> % Data is {We,SplitPlaneNormal}
    {Order,Data};
walk([], Before, [H|T], Data) ->
    walk(H, Before, T, Data);
walk(A, Before, After, Data) ->
    {F,L1,L2,Data0} = distribute(A, Data),
    walk(L1, [F|Before], [L2|After], Data0).

It seems to flatten the "tree" just the way I need.