anchor.diff:                      texCoordses.[u+2] <- v2 texCoordX2 texCoordY2
                       texCoordses.[u+3] <- v2 texCoordX texCoordY
                       texCoordses.[u+4] <- v2 texCoordX2 texCoordY2
  -                    texCoordses.[u+5] <- v2 texCoordX texCoordY
  +                    texCoordses.[u+5] <- v2 texCoordX texCoordY2
                   | None -> ()
   
           // make normals array
  
positive.code:                  Content.staticModelSurface Gen.name
                      [Entity.SurfaceIndex == 1
                       Entity.StaticModel <== field --|> fun field world -> snd (Field.getFieldModelDescriptorsAndAssetTag field world)
                       Entity.RenderStyle == Forward 1.0f]]]]
  
      // here we create the scenery in an imperative fashion
      // NOTE: performance goal: 60fps, current: 57fps.
  
negative.code:                     let tileId = tile.Gid - tileSet.FirstGid
                      let columns = tileSet.Columns.Value
                      let rows = tileSet.TileCount.Value / columns
                      let tileX = tileId % tileSet.Columns.Value
                      let tileY = tileId / tileSet.Columns.Value
                      let texCoordX = single tileX / single columns
                      let texCoordY = single tileY / single rows
                      let texCoordX2 = texCoordX + single tileSet.TileWidth / single tileSet.Image.Width.Value
  