Thursday, 27th of August

Figuring out Rigid Bodies in Blender

Ah, Rigid Bodies. One of the more frustrating parts of Blender. Coincidentally I tried to use Rigid Body simulations twice this week, and the first time with absolutely no success. I gave up after an hour of trying everything I could think of:

  • Changing the scale (Blender doesn’t like to simulate small stuff)

  • Checking for hidden, overlapping objects

  • Setting the collision margin smaller

  • Using Mesh instead of Bounding Box for the collision shape

  • Making sure the scale of the objects was applied

  • Making sure nothing was starting off too close to other Rigid Bodies

  • Setting the origins of all the objects to their center of mass

  • Removing and re-adding the Rigid Body World

  • Increasing the fidelity of the simulation

  • Appending everything in a ‘fresh’ scene, just in case I’d been using some weird setting accidentally

  • Having dangerous amounts of coffee

And yet, whatever I did, this was the result: Instant explosion of all the rigid bodies flying everywhere. And I mean, after frame 1 they would be far away, flung into the void of 3D space. I could only find them by selecting them in the Outliner and pressing the period key.

Then, I tried something wacky: I downloaded a really old Blender - Blender version 2.9. (I almost downloaded 2.8, but for some reason I felt that was going too far). And you know what? Everything I did with Rigid Bodies just worked, very predictably.

So, I’m not sure if it’s some kind of coincidence, it might be my user error. But I wonder if Blender 5.2 maybe has some kind of conflict with the new geometry nodes physics sim and the old method? Or something else… I don’t know! But I was very happy to finally get the results I was expecting in good old Blender 2.9. So finally I baked the simulation to keyframes (and then deleted those weird ‘jiggling’ keyframes that you always get after things have fallen on the floor), and then appended that all back into my Blender 5.2 file, so I could continue working on it.

So I guess my Rigid Body tip is: If all those tips above don’t work, maybe just try an older version of Blender? It worked for me…

Fortunately, all the old Blender versions can be downloaded (apart from some obscure Alpha versions) here:
https://download.blender.org/release/ And see also: https://www.blender.org/download/previous-versions/