 transitionFunc = parseTransitionFunction "B 3 S 2 3", tessellation.group.n, tessellation.group.m
 dragHandler = null
 
-tfm = M.eye()
 cells = new NodeHashMap
 cells.put null, 1
 

    @cellOffsets = (node2array(c) for c in @cells)
    @cellTransforms = (nodeMatrixRepr(c, @tessellation.group) for c in @cells)
    @drawEmpty = true
  rebuildAt: (newCenter) ->
    @center = newCenter
    @cells = for offset in @cellOffsets

  xp = x/s - 1
  yp = y/s - 1
  xyt = poincare2hyperblic xp, yp
  if xyt isnt null
    #inverse transform it...
    xyt = M.mulv (M.inv observer.tfm), xyt
    visibleCell = xytFromCell xyt
    cell = eliminateFinalA appendRewrite(observer.center, node2array(visibleCell)), appendRewrite, tessellation.group.n
    #console.log showNode cell
