 # constants
-qt = Math.PI / 2
+qt  = Math.PI / 2
+tau = Math.PI * 2
 
 # general handle on everything; keeps track of geometry of entities it contains
 class Universe

    return unless radius > 0
    ctx = @universe.ctx
    ctx.beginPath()
    ctx.arc x, y, radius, 0, Math.PI*2
    ctx.fillStyle = color
    ctx.fill()
  setAttributes: ( options = {} ) ->

  # choose a pace to try to place a baby
  babyPoint: ->
    length = 2 * @radius + Math.random() * ( @dispersalRadius() - 2 * @radius )
    angle = Math.random() * tau
    x = Math.round( @x + length * Math.cos angle )
    y = Math.round( @y + length * Math.sin angle )
    # bounce points outside universe back in
