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I have made an animation in which a box rotates, falls down, and explodes.enter image description here

As you can see, there is a round doughnut in the box (there are more boxes and doughnuts but for now I haven't added them and anyway it would be less complex.) When the box falls down, I want this one to collide with more doughnuts like these and get them crushed. So when the box explodes open, I want some food objects (an example shown in the image) to tumble around, collide with each other, and get smashed/crushed. I tried doing this using cell fracture, but it didn't work.

In conclusion, I want some food items to collide and get smashed/cracked (and they're not hollow, they should be solid from the inside). I hope this much detail is probably enough.

Edit: Even the doughnut breaking into 2 pieces after falling down is probably enough, I guess.

Edit: Even though I found a way around cracking/smashing the food, I'm keeping the question open for any more ideas..... of how to do it without it getting hollow from the inside.

Here's the file on dropbox. Since the file is 40 MB (2 attached doughnuts add up to a million faces) blend -exchange takes forever to upload.

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  • $\begingroup$ Is this possible? $\endgroup$
    – Yousuf Chaudhry
    May 23, 2022 at 18:14
  • $\begingroup$ As is, the image doesn't help much. It seems the relevant part of the image is a small donut in the middle. smashing/crushing is not very clear either: Do you want the donut to simply scale down on Z axis to 0, or do you want some physical axis of the dough ripping apart? $\endgroup$
    – Markus von Broady
    May 26, 2022 at 17:05
  • $\begingroup$ Oh and the tag "rigid body simulation" goes pretty much against "smashing", "crushing" or any other form of deformation, by definition of what a rigid body is. $\endgroup$
    – Markus von Broady
    May 26, 2022 at 17:05
  • $\begingroup$ @MarkusvonBroady -- I took a stab at a solution, below. $\endgroup$
    – james_t
    May 26, 2022 at 17:32
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    $\begingroup$ And anyways, since the donut is pretty detailed up close, even after decimating, rigid bodies are very time consuming $\endgroup$
    – Yousuf Chaudhry
    May 28, 2022 at 14:04

2 Answers 2

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Yes it is possible, try out this example blend file. Be sure to "Bake" the soft-body simulation included. (unfortunately the blend-exchange upload site is rejecting blend files again today!!! UGH)

I use two modifiers: Soft Body for the crushing effect, and Explosion for enhancing with some crumbs falling away after the collision of two spheres.

Soft body will deform your donut:

enter image description here

You'll see that I created two vertex sets: Goal set is used in the SB goal properties, so that the object can be somewhat pinned and not fall away. I didn't add a collision plane (bottom of box) and could have used that instead of pin-goals.

then I included all vertices in vertex group 'Springs' to participate in the Edges parameters of soft body. Not that I set Plasticity to the max of 100, so that the donut would not spring back after the collision:

enter image description here

To include some crumbs falling off, I included the Explosion modifier onto the donut. I used the Object >> Quick Effects >> Explosion, so that the particle system would also be set up for me (I guess you've already used this in your question so are familiar). I selected a group of vertices to participate, then Select >> Invert and added these to the vertex group 'Explode'. I did some weight-painting to include a bit beyond what I selected:

enter image description here

This gives me the crushing plus crumbs effect you may be looking for:

enter image description here

If you are going to do this for may donuts, the crumbs effect may be a bit tricky to figure out -- where will the collisions occur and how to vary this so it doesn't look artificial.

If you want the boxes to crush the donuts -- you may have to make your particles into objects that have Collision modifiers.

If you want several donuts to "crush" each other -- add a Collision modifier to these as well. Depending on the number the Bake time may be rather onerous.

And per your solidify comment below, I add a Solidify modifier with a separate material for the internal, less-browned cake:

enter image description here

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    $\begingroup$ I would hope for some animation of the crushed/smashed/exploding donut :). If you make sure the blend-exchange doesn't work, you might want to write in the thread again. BTW in regards to explosions, I've recently made one in geonodes, though geonodes aren't iterative so you need something to control that effect... i.imgur.com/eilcCVs.gif - I actually control it with vertex weights stage i.imgur.com/EolzeS1.png, so perhaps you could draw on it with dynamic paint... $\endgroup$
    – Markus von Broady
    May 26, 2022 at 18:58
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    $\begingroup$ Thanks, nice solution! @MarkusvonBroady you too. However, the problem I mentioned that forced me of this workflow (I decided to skip the smashing, but I'm keeping the question open for more ideas for future reference and help to anyone who searches), was that the object inside should not appear hollow, since it would be visible. (and of course there is no such thing as a hollow doughnut) $\endgroup$
    – Yousuf Chaudhry
    May 28, 2022 at 14:08
  • $\begingroup$ @ChaudhryYousuf -- good point. What about the solidify modifier? I've updated my answer (and file). You'd only see this in places where the doughnut gets chipped (explosion-removed surfaces), which is imperfect. Perhaps this can be improved by reducing the explosion effects so that pieces don't travel far: I added a clear surface collision object. $\endgroup$
    – james_t
    May 29, 2022 at 15:40
  • $\begingroup$ I would say these solutions are pretty good, but what about when it comes to detailed objects like in my image? Doing these tricks on primitive shapes work at my end too, but what I'm experimenting with is something much more detailed. I have edited my question to include the doughnut I have attached in the image. (By the way, It's more of a sphere than a doughnut ;) ) $\endgroup$
    – Yousuf Chaudhry
    May 30, 2022 at 11:06
  • $\begingroup$ @ChaudhryYousuf -- meshes are meshes, no matter what the starting shape, and I like my jelly/cream-filled doughnuts on a rare occasion! But I am more a french bread/pastry fan (baguettes, croissant) :). If you want more input on your "detailed" mesh, you may need to include a small sample file, but that might give away your proprietary design, sadly. $\endgroup$
    – james_t
    May 30, 2022 at 16:47
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Might want to try cell fracture plugin, start with soft body collision then at some frame switch to fractured objects with rigid body simulation. Depending on camera might need to apply subsurface and decimation to make the bits look a little softer.

enable cell fracture plugin apply to donut results

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  • $\begingroup$ Interesting. Time to experiment ! $\endgroup$
    – james_t
    May 29, 2022 at 15:44
  • $\begingroup$ The question used to mention Cell Fracture but then it was removed... $\endgroup$
    – Markus von Broady
    May 29, 2022 at 23:04
  • $\begingroup$ Yes, because for some reason, the fractured pieces seemed very intent on exploding so far in one frame that they just disappeared. Even though I made sure the meshes weren't intersecting. $\endgroup$
    – Yousuf Chaudhry
    May 30, 2022 at 10:23
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    $\begingroup$ @ChaudhryYousuf i had the same issue with the initial velocity for the cell fractures after adding rigid bodies. Was going to suggest applying a displace modifier to create space between the cells, but I'm having difficulty recreating the problem with convex collision hulls. $\endgroup$
    – Lowlande52
    May 31, 2022 at 4:50
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    $\begingroup$ problem solved! youtu.be/Xdrz7icUvC4?t=174 $\endgroup$
    – Lowlande52
    May 31, 2022 at 4:52

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