anchor.diff:      let cloud =
           Sg.pointCloud data {
               targetPointDistance     = Mod.constant 40.0
  +            maxReuseRatio           = 0.5
  +            minReuseCount           = 1L <<< 20
  +            pruneInterval           = 500
               customView              = Some (gridCam |> Mod.map CameraView.viewTrafo)
               customProjection        = Some (gridProj |> Mod.map Frustum.projTrafo)
               attributeTypes =
  
positive.code:                 |> Sg.effect [
                      DefaultSurfaces.trafo |> toEffect                  
                      DefaultSurfaces.vertexColor  |> toEffect         
                      DefaultSurfaces.pointSprite  |> toEffect     
                      DefaultSurfaces.pointSpriteFragment  |> toEffect 
                  ]
              Helpers.frustum gridCam gridProj
  
  
negative.code:     // ===================================================================================
      type PointCloudInfo =
          {
              /// the element-types for all available attributes
              attributeTypes : Map<Symbol, Type>
  
              /// the target point distance in pixels
  