Use your fingers or mouse to control model
(hold shift key or use mouse wheel to zoom it).
Random dichotomic tree with environment lights.
New twig is accepted if it is not shadowed
(there is no neighbour above or to the left, right, before or behind).
128x128 array is used to store top heights.
Top height values make draft tree outline. It is used to
make more realistic leaves shadowing.
"Shadowing" trees are fast and funny.
I'm not sure if foliation is accurate (not self intersected).
7 trees demo with only top lights.