anchor.diff:                              for v in q1.EdgeLines do
                                   let mutable t = nan
                                   match u.Ray2d.Intersects(v, &t) with
  -                                    | true when t > 0.1 && t < 0.9 -> yield true
  +                                    | true when t > 0.001 && t < 0.999 -> yield true
                                       | _ -> ()
                       }
                   realIntersections |> Seq.isEmpty |> not
  
positive.code:                         let p2Inside = p2.PosLeftOfLineValue(p0, p3) > 0.0
  
                          let overlapping = allSplines |> Seq.exists (overlap q)
                          if overlapping && not (p1Inside || p2Inside) then
  
                              let m0 = 0.5 * (p1 + p0)
                              let m1 = 0.5 * (p1 + p2)
  
negative.code:                |> Sg.projTrafo (perspective |> Mod.map Frustum.projTrafo    )
           
                 |> Sg.fillMode fillMode
                 //|> Sg.andAlso osg
  
                 |> Sg.trafo (Trafo3d.FromOrthoNormalBasis(V3d.IOO, -V3d.OIO, -V3d.OOI)  |> Mod.constant)
                 //|> Sg.trafo (win.Sizes |> Mod.map (fun s -> Trafo3d.Scale((float s.Y / float s.X), 1.0, 1.0) * Trafo3d.Scale(size, size, 1.0)))        
  