The reubild frequency of the spatial tree was causing calculations to
operate on old information. This is not the intended behavior. The
default schedule seems to be to run every frame.
I also lowered the debug pointer coefficient. Boids moving at a normal
velocity are actually fast enough to draw a meaningful line. Maybe I'll
switch it into some kind of exponential space so small changes are
visible, and big changes don't draw a line all the way across the
screen.
Robert Garrett
bb33fda018