anchor.diff:  
           let viewTrafo = DefaultCameraController.control win.Mouse win.Keyboard win.Time view
   
  +        let colors = [| C4b.Gray; C4b.Green; C4b.Red; C4b.VRVisGreen; C4b.Blue; |]
  +
           let rand = Random()
  -        let randomPoints (bounds : Box3d) pointCount =
  +        let randomPoints (bounds : Box3d) level pointCount =
               let randomV3f() = V3d(rand.NextDouble(), rand.NextDouble(), rand.NextDouble()) * bounds.Size + bounds.Min |> V3f.op_Explicit
  -            let randomColor() = C4b(rand.NextDouble(), rand.NextDouble(), rand.NextDouble(), 1.0)
  +            let randomColor() = colors.[level]// C4b(rand.NextDouble(), rand.NextDouble(), rand.NextDouble(), 1.0)
   
               IndexedGeometry(
                   Mode = IndexedGeometryMode.PointList,
  -                IndexArray = Array.init pointCount id,
                   IndexedAttributes = 
                       SymDict.ofList [
                            DefaultSemantic.Positions, Array.init pointCount (fun _ -> randomV3f()) :> Array
  
positive.code:         use app = new OpenGlApplication()
          let win = app.CreateSimpleRenderWindow(1)
     
          let view = CameraView.LookAt(V3d(150.0,150.0,150.0), V3d(50,50,50), V3d.OOI)
          let perspective = 
              win.Sizes 
                |> Mod.map (fun s -> Frustum.perspective 60.0 0.1 1000.0 (float s.X / float s.Y))
  
negative.code: 
          let sg = 
              scene |> ASet.mapM ( getLodRepr viewTrafo perspective ) 
              |> Sg.geometrySet IndexedGeometryMode.PointList attributeTypes
              //|> ASet.map Sg.ofIndexedGeometry |> Sg.set
  
  
          let final =
  