anchor.diff:  module TrefoilKnot = 
       open SharpGL.SceneGraph.Shaders
       open System.Collections.Generic
  -    //open SharpGL.Shaders
  +    open SharpGL.Shaders
       open SharpGL.Enumerations
   
       //  Original Source: http://prideout.net/blog/?p=22
  
positive.code:         //  Add a bit to theta (how much we're rotating the scene) and create the modelview
          //  and normal matrices.
    
          theta <- 0.01f
          scene.CreateModelviewAndNormalMatrix(theta)
              
          //  Clear the color and depth buffer.
  
negative.code:     let vertexCount = slices * stacks
      let indexCount = vertexCount * 6
  
      let mutable vertices : vec3[] = Array.init<vec3> vertexCount (fun _ -> new vec3()) 
      let mutable normals : vec3[] = Array.init<vec3> vertexCount (fun _ -> new vec3())
      let mutable indices : uint16[] = Array.init<uint16> indexCount (fun _ -> 0us)
  
      let vertexBuffer = new VertexBuffer()
      let normalBuffer = new VertexBuffer()
  