(program	
 (fun vertex vs_main -> float4 (@position)
  [(:= pos float3 (@position))] 
  (if (> pos.x 100)
      (return (float4 pos 1))
      (if (> pos.x 50)
          (return (float4 pos 1))
          (return (float4 1)))) 
  (return (float4 0))))