Hello guys,

thanks for clicking this post,

I am trying to make a basic cableway but unfortunately I got stuck at one point. I was trying to put there windows but the glass panes don´t seem to work properly. They are not solid, just regular planes with a material which I´ll put a screenshot of. It looks as if they had different behavior on each side but I don´t understand why. Can you help me find the solution?

enter image description here One side of the cableway (this one looks good)

enter image description here and the other side... (Same lighting and everything, just different camera position)

enter image description here ... And this is the material I use for the glass panes.

Thanks for your time, Daniel!

  • 1
    $\begingroup$ Did you check the normals on the back planes? They might be pointing inward on one side and outward on the other side. They should all be pointing outward. Also, if you're using Cycles render, you could just use the "Glass" shader. $\endgroup$ Dec 31, 2018 at 1:35
  • $\begingroup$ @ElliotThomas I was told that if you´re using just a plane, not a solid shape, it is better and easier to use this material instead of the glass, is it not? I really don´t know but you might be right. And I´ll check the normals, thank you! $\endgroup$ Dec 31, 2018 at 11:51

1 Answer 1


Your 'Fake Glass' using a single plane instead of a solid works as expected when the plane is viewed from the 'front' side (the side that the normal is facing) but the Fresnel node produces different results when viewed from the 'back'. In order to correct for this you need to adjust the IOR to 1/IOR when viewing the surface from the 'back' and this can be achieved as follows :

fresnel adjusted for back-facing

Here the Backfacing geometry node controls the Mix between IOR and 1/IOR so that when viewed from the 'back' of the surface it still behaves the same as from the 'front'.

Replace the Fresnel node in your example with the above nodes and this should resolve your problem.


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