anchor.diff:  
               // get active stream information for stream 0.  currently we ignore other streams (will log a warning below if the declaration
               // uses data from non-stream 0).
  -            let mutable vb:VertexBuffer = null
               let mutable offsetBytes = 0
               let mutable strideBytes = 0
   
  
positive.code: 
              // lock vb and ib
              let vbDS = vb.Lock(0, vb.Description.SizeInBytes, LockFlags.ReadOnly)
              if not vbDS.CanRead then failwith "Failed to lock vertex buffer for reading"
              use vbReader = new BinaryReader(vbDS) // disposable
  
              let ibDS = ib.Lock(0, ib.Description.Size, LockFlags.ReadOnly)
              if not ibDS.CanRead then failwith "Failed to lock index buffer for reading"
              use ibReader = new BinaryReader(ibDS) // disposable
  
  
negative.code:                 |> List.map (fun i ->
                      let texName = sprintf "%s_texture%d.dds" sbasename i
                      let texPath = Path.Combine(baseDir, texName)
                      // log.Info "Saving texture %d to %s" i texPath
                      if saveTexture(i, texPath) then
                          i,(texName,texPath)
                      else
  