anchor.diff:          )
   
           
  -        tessGrid 64
  +        tessGrid 128
               |> Sg.ofIndexedGeometry
               |> Sg.effect [ 
                   Shader.pgmVertex |> toEffect
  -                Shader.pgmHeight |> toEffect
  +                //Shader.pgmHeight |> toEffect
                   Shader.pgmTessControl |> toEffect
                   Shader.pgmTessEval |> toEffect
                   Shader.pgmFragment |> toEffect
  
positive.code: //            let c = V2d (V2i (c / pixelSize)) * pixelSize + V2d(pixelSize / 2.0, pixelSize / 2.0)
  //            let tc = c / V2d heightSampler.Size
  
              let h = heightSampler.SampleLevel(tc, 0.0).X * heightScale
              let wp = world + V4d(0.0, 0.0, h, 0.0)
              wp
  
  
negative.code:                 return { innerLevel = [|i0; i1|]; outerLevel = [| t0; t1; t2; t3 |]}  
              }
  
  
  
  
  
  