Blast with an imported mesh

Omniverse General Discussion
1

Hi,
what’s the workflow for using Blast with an imported mesh ?
Fracture and physics is working fine with a basic mesh, created inside Omniverse Create. (for ex. sphere, cube, etc)
But I can’t figure out to fracture and apply the physics to an imported mesh.

Thank you
Jeff

2

Once you import the mesh, the process should be the same as if you create a cube in Create. You apply a physics rigid body (assuming you want it to collide) then select it and fracture it with Blast. If that is not working, could you please provide your exact repro steps? Thanks!

3

Hi Eric,

import with fbx - translate to USD
select everything, physics / create physics scene
select mesh physics / set rigid bodies
select mesh Blast / fracture chunks are created
physics / create a ground plane
play

my mesh doesn’t crumble in piece, bounce on the floor as a single piece ?

I like your profile image.
Thanks

4

Would you be able to attach your FBX file so I can try it out locally?
It sounds like you are doing things right, I’m not sure what would be going wrong here.
You shouldn’t have to select everything when creating the physics scene, that is adding general data to the stage, it doesn’t depend on anything being selected.
What version does your Blast extension show in the Window → Extensions menu?

5

Another thing to check is the value of “Contact Threshold” in the Blast panel. We’ve had 2 people get an extremely large value in there (not sure how yet). If that is a huge number it will prevent physics from reporting collisions for the body, so it won’t fracture. The value updates when you select a prim, so select the fractured mesh in the Viewport (not the Stage).

If the value is large, you can click “Reset All to Default” at the top of the panel and refracture the mesh and it should behave properly. Please let me know if that fixes it for you.

6

Hi Eric,
it’s the issue I guess. The “Contact Threshold” has a value of 3402823466385288975906360464416.
Still I don’t see “Reset All to Default” at the top of the panel .
Using v0.4.10

7

Ah, I think that is in the version that is about to be release then. You should be able to set it manually. If you select “yourPrim__blast\actors\a0” and then change that value to something like 10,000 it should start breaking apart when it hits the ground. We haven’t been able to repro how that value is getting corrupt like that yet. If by chance you figure out how to make that happen, please let me know so we can fix it.

8

Yes, it’s working now.
Changing the value in the “Contact Threshold” Blast panel.
Sorry don’t know my process to break the values.
Omniverse is so new, I’ve been doing many things…
Thank you

9

Glad it is working for you! Let me know if I can help with anything else