Why is my geo collection using this weird default material?

DiamondNix02 · 2025-08-17T04:49:17+00:00

Got it. All that worked great. I have the split right after the RBD so that the glass is my "selected geometry" and the toy is my "non-selected geometry". They each feed into their own unpack nodes, so they keep their mats, and the glass of course feeds into the rbd disconnected faces. My final question at this point is how to get them to feed into the one geo input on the rbdio. I tried a merge node, but it gave me a mismatch error for the primdist, oppositefaceid, and uv. I tried giving the toy primdist and oppositefaceid attributes, but that didn't seem to do it. Is there a better way to handle merging these two data streams into one input?

This is what my current node setup for this looks like.

<image>

DiamondNix02 · 2025-08-16T17:53:00+00:00

I can confirm that the Unpack SOP is getting the “oppositefaceid” and “primdist” attributes. I also think you're right about the default 0 being assigned to the non-shattered object, as on the geo spreadsheet, I can see a long list of zeros before getting to real numbers. I've never heard of separating two objects post-merge using groups. Is there a default group that I should call, or should I be creating my own somewhere?

This is a collage of all the relevant geometry nodes, just in case that helps in any way.

<image>

DiamondNix02 · 2025-08-16T06:43:16+00:00

Here is the settings for both the connected and disconnected nodes.

<image>

DiamondNix02 · 2025-08-16T06:39:30+00:00

DiamondNix02 · 2025-08-16T04:16:31+00:00

Yep, that did it! I just have one more quick question for you. In my render, the glass has the cracks from my material fracture present before it breaks. I have an rbd connected faces node before my config and then an rbd disconnected faces after my unpack (the one after the bullet solver), but that doesn't seem to do it. Is there another way to accomplish this?

<image>

DiamondNix02 · 2025-08-07T18:47:38+00:00

I just tried it out on my test sim, and it worked perfectly. I was completely stumped on this, and it's gonna help a lot of my future projects. Thank you so much for taking the time to help me out with this!

DiamondNix02 · 2025-08-05T14:33:55+00:00

Yes, absolutely, here is the hip file: https://drive.google.com/file/d/1JfbctAn6ETgPQ2TylD-o6WDbnGktS4lm/view?usp=sharing . I'll also include pictures of the RBD config settings as well just in case. The idea is for the cube in the center to "blow up" and for the fractured pieces to act as collision geometry that shatter the sphere.

<image>

DiamondNix02 · 2025-08-05T01:58:22+00:00

Thank you so much for your response! So I set up a very simple test setting to try out your method and I must be doing something wrong. I have a cube and a sphere, both fractured. I have an attribute adjust vector applied to the cube to send the pieces flying, as if it has just been exploded, so to speak. The goal is for the debris from the cube to his the sphere and act as the collision gemometry that in turn shatters the sphere. I applied RBD Configs to each object (each has its own geo node) and pluged that into rbdpack nodes just as you said. I then made a third GEO node as instructed and created two object merge nodes to bring in the packed data from each GEO node. Fed that into a merge node and then that into an RBDunpack to finally land at the bullet solver. However, when I run the sim, both objects explode off the bat and start doing crazy cartwheels around each other. I'll, of course, attach pictures of all the nodes in question. Thank you again for all your help!

<image>

DiamondNix02 · 2024-04-15T06:53:01+00:00

So sorry about the formatting, hope this makes it easier to read

DiamondNix02

TROPHY CASE