anchor.diff:          Array.Resize(&arr, cnt)
           arr
       
  -    // Patch Size to index array (skipping faces with invalid points)
  -    let computeIndexArray (size : V2i) (invalidPoints : int Set) =
  +    // Patch Size to index array (faces with invalid points will be degenerated or skipped)
  +    let computeIndexArray (size : V2i) (degenerateInvalids : bool) (invalidPoints : int Set) =
         // vertex x/y to point index of face
         let getFaceIndices y x sizeX =
           let pntA = y * sizeX + x
  
positive.code:             positions.Data |> Array.map (fun x ->  x.ToV3d() |> matrix.TransformPos)
  
          let invalidIndices = getInvalidIndices data
          let index = computeIndexArray (positions.Size.XY.ToV2i()) (Set.ofList invalidIndices)
                
          let triangles =             
              index 
  
negative.code:         [| pntA; pntB; pntC;
             pntC; pntB; pntD |]
      
        // replace invalid faces with another array (invalidReplacement)
        let getFaceIndicesWReplacedInvalids invalidReplacement y x sizeX =
          let faceIndices = getFaceIndices y x sizeX
          if faceIndices |> Array.exists (fun i -> Set.contains i invalidPoints) then 
            invalidReplacement
          else 
            faceIndices
            
        // choose function to use
        let f = 
          match (invalidPoints.IsEmptyOrNull(), degenerateInvalids) with
          | (true, _)      -> getFaceIndices
          // skip faces with invalid points
          | (false, false) -> getFaceIndicesWReplacedInvalids Array.empty
          // replace invalid faces with degenerated face
          | (false, true)  ->
              // find first valid point
              let p = [| 0..(size.X * size.Y - 1) |] |> Array.find (fun i -> not (Set.contains i invalidPoints))
              getFaceIndicesWReplacedInvalids [| p; p; p; p; p; p |]
          
        // step through all vertices to get index-array per face      
        let indexArray = 
          [|
            for y in [| 0..(size.Y-2) |] do
              for x in [| 0..(size.X-2) |] do
                yield f y x size.X
          |]
      
  