anchor.diff:                      let position = &positions.[u+5]
                       position.X <- (positionM1.X + position.X) / 2.0f
   
  -            let normals = Array.zeroCreate<Vector3> (tileMap.Width * tileMap.Height * 6)
  -
  -            for i in 1 .. dec tileMap.Width do
  -                for j in 1 .. dec tileMap.Height do
  -                    let u = i * tileMap.Width + j
  +            let normals = Array.zeroCreate<Vector3> (tileMapWidth * tileMapHeight * 6)
  +
  +            for i in 1 .. dec tileMapWidth do
  +                for j in 1 .. dec tileMapHeight do
  +                    let u = i * tileMapWidth + j
                       let normal = Vector3.Normalize (Vector3.Cross (positions.[u+1] - positions.[u], positions.[u+5] - positions.[u]))
                       normals.[u] <- normal
                       normals.[u+1] <- normal
  
positive.code:                         texCoords.[u+5] <- v2 texCoordX texCoordY
                      | None -> ()
  
              let positions = Array.zeroCreate<Vector3> (tileMap.Width * tileMap.Height * 6)
  
              for i in 0 .. dec tileMap.Width do
                  for j in 0 .. dec tileMap.Height do
                      let t = i * tileMap.Width + j
                      let tile = untraversableHeightLayer.Tiles.[t]
                      let mutable tileSetOpt = None
                      for (tileSet, _) in tileSets do
                          match tileSetOpt with
                          | None ->
                              if tile.Gid = 0 then
  
negative.code: 
  module Field =
  
      let CachedGeometries = dictPlus HashIdentity.Structural []
  
      let private createGeometryFromLayers tileMapWidth tileMapHeight (tileSets : TmxTileset array) (tileLayer : TmxLayer) (heightLayer : TmxLayer) =
          
              let texCoords = Array.zeroCreate<Vector2> (tileMapWidth * tileMapHeight * 6)
  
              for i in 0 .. dec tileMapWidth do
                  for j in 0 .. dec tileMapHeight do
                      let t = i * tileMapWidth + j
                      let tile = tileLayer.Tiles.[t]
                      let mutable tileSetOpt = None
                      for tileSet in tileSets do
                          match tileSetOpt with
                          | None ->
                              if tile.Gid = 0 then
  