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I want to Animate a Crack/Split forming progressively. It should achieve a similar look as in the following gif which i have taken from this video: https://youtu.be/faG0A4hTMGw

enter image description here

I'm specifically talking about how the Crack in the middle forms, which comes from the bottom part of the nib(not the ornamental engraving), and at the end also creates the circular hole in the topology, which would change up the topology. Right now I'm trying to animate it using a boolean modifier and animate the boolean cutter. My problem with that is, that since it is destructive, i can't really clean it up using bevel/subdivision modifier. I have tried animating using shape keys, but in my opinion they don't work that well for what I'm trying to do.

Here is what I have so far using boolean modifier: enter image description here enter image description here

Any help is appreciated. Tutorials or other posts on this topic would also be a big help, since i don't know how to research this topic.

(I have figured, that I would do the animation of the ornamental engraving by using a shrinkwrap modifier, which is driven by dynamic vertex paint. If you have a better idea on how to achieve that look better please let me know.)

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  • $\begingroup$ Hello and welcome. While files, images, and external videos or links may be helpful additions they should not be the only way to obtain information about your issue. Don't make understanding your question rely on downloading a file, watching a video or visiting an external site. Use the builtin tools to upload images or gifs, along with thoroughly explaining the problem in written form so it can be indexed and searched for thus helping future visitors with similar issues. $\endgroup$
    – Duarte Farrajota Ramos ♦
    Commented Feb 1, 2022 at 21:47
  • $\begingroup$ maybe you can animate with bones? and to make sure that you don't see the join at the beginning you can use the Data Transfer modifier, it will allow you to copy the split normals of a non broken version of your object $\endgroup$
    – moonboots
    Commented Feb 2, 2022 at 10:14

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One approach to this would be to use an animated bump-map.

  • Construct your engraving as a curve in the XY plane . You can test it for radius, etc, using its native Bevel, set in its Geometry panel (left, below)...

enter image description here

  • When done, though, set its Bevel back to 0. For convenience, we're going to put it through a Geometry Nodes modifier, and we want it to be a curve, not a mesh, when it gets there:

enter image description here

A curve doesn't have a 'Generated' texture-space, and to map its height conveniently, we could do with one. The GN group above grabs the max and min Z of the curve's bounding box and maps those to a range -1 to 1. We only want the 0-1 half, above the XY plane.

Add a black emissive plane in XY as a background,

  • Simply shade the curve with the output 'Height' from the GN group (I called mine 'h' in the modifier):

enter image description here

  • In this simplified case the 'Trim' of the curve is keyframed.. all its splines grow together. You could split those off as separate objects, or treat them differently in the GN tree.
  • Shoot the animation of the curve and the bg plane from directly above, with an Orthographic camera, obtaining an image sequence something like this:

enter image description here

.. which can be used in a material something like this one, to shade your metallic surface. Here, it's used to make the bottom of the grooves a bit rougher, too:

enter image description here

With this kind of result (not flattered by the .gif):

enter image description here

If, instead of plugging the image sequence into the Roughness of the BSDF, you plug a threshold of it into the Alpha:

enter image description here

You get a pretty good perforation:

enter image description here

At least, good enough to carry you over to a cut / dissolve :)

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    $\begingroup$ thank you! that is very helpful and I will definitely keep that in mind. Unfortunately I didn't make myself clear enough, as I need help making the split/crack animation in the topology, meaning the $\endgroup$
    – LetMeStay2
    Commented Feb 2, 2022 at 18:02
  • $\begingroup$ Hi @LetMeStay2 ! Sure; that's why I deleted my answer, initially. I'm fairly confident, though, that the lengthening straight-slot in this video will have been made with a method something like this one. The nib never bifurcates in-shot. At the end, the nib splays, but by then it is already separated (The slot is physical, for that shot, and partially concealed by the ink-object). There's also a lot of cross-cutting being covered by depth-of-field, IMO. The round hole could be a bump, too. Just add a cylinder or a sphere to the height-map. $\endgroup$
    – Robin Betts ♦
    Commented Feb 2, 2022 at 18:42
  • $\begingroup$ Thanks for the Reply @Robin Betts, Do you have any Idea how bifurcations in 3d animation are done generally? I feel like it should be quite important in 3d animation, yet I can't seem to find anything on the internet explaining this. $\endgroup$
    – LetMeStay2
    Commented Feb 2, 2022 at 22:21
  • $\begingroup$ @LetMeStay2 Personally, I think it's always tricky, automating the creation of clean polygonal surfaces, so it's always case-by-case. (Others may contradict me.) In my commercial experience, only the pixels matter, and it's a question of getting them right enough, and in the can as quickly as possible.. ( Think: Ian Hubert ) so more often than not, splits would be allowed to survive to post-production, and painted over. I think the above method works for your case as described. But by all means, specify further :) $\endgroup$
    – Robin Betts ♦
    Commented Feb 3, 2022 at 5:50

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