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I have a metre device with one handle, which rotates, clockwise. I'd like to know how to make cracks appear gradually from the centre of the device and go outwards. When the cracks appear from a smooth transition to more intense cracks, (as the hand goes from 0 to 100).

PS: Also the cracks remain on the object, they do not fall, or have colliding object.

PS: If masking method is needed, I can do it with builder modifier to reveal the animating cracks.

enter image description here

Here a few examples:

( This one has cracks, but they disintegrate and fall apart, I'd just like the cracks to appear gradually)

https://www.dreamstime.com/destruction-chocolate-surface-white-ice-cream-filling-chocolate-surface-white-ice-cream-filling-cracks-breaks-video249313129

https://www.dreamstime.com/cracks-wall-green-screen-motion-graphics-earthquake-video195952942

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2 Answers 2

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So let me show you my approach.

  1. Enable Cell Fracture add-on

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  1. Get your object to crack and make sure that it has thickness and scale is applied. Add a particle system to it:

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Number - amount of cracks
Frame end - 1

  1. Open Object -> Quick effects -> Cell fracture.

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You can play with settings, I have left all by default.

  1. After few seconds you will get cracked object pieces in the place. Hide original mesh after cracks has been generated. Select all cracks and move into a new separate collection.

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You can select all of them by select -> select pattern. Then press M -> new collection.

  1. Then make new mesh (cube for example, points will not be used), add a new geometry nodes modifier and put the collection with cracks into the geometry nodes output, replacing original geometry:

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  1. Put scale and set position between the nodes. And check separate children so that we can move cells separately.

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  1. Add Empty object in the scene, we will use it as controller.

  2. Use vector math node in distance mode to calculate distance between the empty and each crack:

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  1. Use map range node to set up influence:

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this is the final result:

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  • $\begingroup$ Hi, I am adding a particle system and Im getting spheres generating: ibb.co/YfXSk7w $\endgroup$ Feb 21, 2023 at 8:33
  • $\begingroup$ In Step 5, when you instruct: Make new mesh, do I make again new mesh with generated Cracks? I'm confused from this step. $\endgroup$ Feb 21, 2023 at 8:40
  • $\begingroup$ Hide original mesh after cracks has been generated. Step 5 - add a new mesh, a cube for example, it doesn't matter, because its vertices will be replaced by collection with cracks. $\endgroup$
    – Crantisz
    Feb 21, 2023 at 9:00
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I don't know if there'd be a shader or particle approach -- I couldn't think of one.

Possible approaches would include ideas to "fake out" the appearance of the cracked surface.

Here, I have a second surface (object), slightly rounded (squashed sphere), with some animated shape keys, that is then animated to move above the surface.

enter image description here

Some other fake approaches might be to un-Decimate a more static overlay.

However, if you are looking for cracks to form crack-by-crack, with increasing/snaked channels, these are not good approaches. You might instead need to create an animated gif or sequence of images.

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