     @x = attrs.x
     @y = attrs.y
     @key = attrs.key
+
+  # returns true if the node hasn't good coordinates
+  bad_node: =>
+    return true unless @x? && @y?
+    return true if @x == 0 && @y == 0
+    false
 
 class Link
   constructor: (left, right) ->

    for l in data.links
      left = @nodes_map[l.left]
      right = @nodes_map[l.right]
      @links.push new Link(left, right)

    @svg = d3.select('#topology')
      .append('svg')

        classes: "ui-tooltip-tipsy"

  rescale: =>
    trans = d3.event.translate
    scale = d3.event.scale
    @svg.attr("transform", "translate(#{trans}) scale(#{scale})")
