I want to colorize these stylised bronchial tubes in an animation from the top (wider tube) to the bottom (narrow tubes). Do you have an idea how to achive this? Maybe with animation nodes? How would you do it?

Ideas are very welcome, thank you in advance!

enter image description here

  • $\begingroup$ i don't think that's possible...but i am very curious for the answers here... ;) It should be possible with python so... $\endgroup$
    – John MC
    Sep 4, 2021 at 14:23
  • 2
    $\begingroup$ Have a look at the answers here, and the links out to @Pali's OSL scripts. 'Thickness Shader' might be a good search-term. $\endgroup$
    – Robin Betts
    Sep 4, 2021 at 14:54

1 Answer 1


I would do a UV Unwrap > Project from View, align the UV islands (subtrees) along the Y(V)-axis, and use a UVWrap modifier with 2 Empties or a driver in the Mapping Node to animate it:

example animation

If you want to make it perfect you need to rotate and align every branch top-down. I did it only for the main branches:

UV map

Set the extrapolation mode for the Image Textexure node to Extended:

material setup

Use the UV Warp modifier or the Y value of the Mapping node to animate the color.

  • $\begingroup$ Very smart solution! Thank you @Blunder! $\endgroup$
    – Chrischan
    Sep 5, 2021 at 6:43

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