     w = @universe.width
     h = @universe.height
     if @universe.torus
-      x = ( x + w ) %% w
-      y = ( y + h ) %% h
+      x = x %% w
+      y = y %% h
     else
       if x < 0
         x *= -1

dfh.Universe = class Universe
  # default initialization parameters
  defaults: ->
    torus: true
    width:  500
    height: 500
    cell:   20

    h = @height
    if x - radius < 0 || x + radius >= w || y - radius < 0 || y + radius >= h
      if @torus
        map points, (p) -> [ p[0] %% w, p[1] %% h ]
      else
        grep points, (p) -> 0 <= p[0] < w && 0 <= p[1] < h
    else
