Cineversity

I have a scene where tumbleweeds are colliding with a wall. Project link here:

https://shared-assets.adobe.com/link/c7adfe9e-51a9-40e2-45db-a3858171eff2

The tumbleweed mesh appears to be too dense (or too thin) to work well with dynamics. If I use a soft body tag, it crashes the program. If I use a rigid body, the mesh doesn’t behave realistically. So to avoid this, I used a buckyball inside an Atom Array as a proxy in the scene. I set up the soft body and wind parameters to create the motion paths I need. I then baked the dynamics cache on each ball. Everything works perfectly.

My naive intention was to put a constraint tag on the tumbleweed and link it to the dynamic buckeyball. Of course, that didn’t work. Next I tried to create an alembic object from the buckeyballs and then bake the keyframes into a timeline. My expectation is if I could get real keyframes, I could track them with a constraint tab as originally planned. But try as I might, I’m not able to find a way to bake keyframes from an alembic object driven by dynamics. Maybe Athanasios covers that in his tutorial on what’s new in R20, but I wasn’t able to find that reference.

Am I wrong to think I should be able to generate a keyframe sequence from an alembic object or dynamics cache?

Hi fordmar,

Thanks for the file:

I would create an object similar to the shape of the tumbleweed—very few polygons. After you have stored the animation, this can be used with the Mesh Deformer.

Rough example with your file.
https://www.dropbox.com/s/ngujg35iwndr54h/CV3_2023_drs_22_CAmd_01.c4d.zip?dl=0

https://help.maxon.net/c4d/2023.0/en-us/Default.htm#html/OCAMESHDEFORMER.html

You can build a new cage with Volume
https://www.dropbox.com/s/vvp6p55mm1wr6ne/CV3_2023_drs_22_MOca_01.c4d.zip?dl=0
Then use the Current State to Object. Which should allow for an excellent dynamic while keeping the data reasonable.

All the best

Ah! Of course - brilliantly simple (as always). The mesh deformer serves double duty - adding squash and stretch to the tumbleweed model while tracking the motion path like a constraint tag. Very cool.

Thank you!

You’re very welcome, fordmar!

Thank you for the kind comment.

My best wishes for your project.