MPM Solver - General Understanding

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Hey there,

I played around with the MPM solver and the presets that came with the new release.

I am a bit confused about the output of the solver, since it produces all these points.
For a fluid and grain like sim this makes sense but for stuff like the building example its unclear to me how to use this data. The MPM softbody example uses point deform to match the sim points with the original mesh but for other example i find that doesnt work.

For example the metal tearing preset... Is the idea here that you create a VDB from particles after the sim?

Maybe someone can shine light in that for me please.

Thanks in advance!
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Bump. I got confused as well. For example in the "Building Collapse" example, in real world scenario you're building would be a polygon model, right? How do you shatter the polygon model given your simulated MPM particles?

For example, this fruit demo:



The peel seems to have textures and UV, so it's not just a VDB, right? How to get this from MPM particles?

What's the equivalent of "Fluid Meshing" for solid objects?
Edited by kodra - July 11, 2024 22:22:48

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Maybe the outside its vellum and the inside its MPM.

I dont think MPM its for break a buildings or hard stuff its just slow as hell compared to bullet.Maybe for some internal parts to give more granular feel.
Edited by Jorge Ivanovich2 - July 12, 2024 10:12:22
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Yeah it would be interesting to see some production usage cases on this. Bumping up the point separation really kills the supposed speed increase over classic methods. Would love to see the point count for their avalanche demo!
Edited by Bleip - July 12, 2024 10:17:41
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Jorge Ivanovich2
Maybe the outside its vellum and the inside its MPM.

I dont think MPM its for break a buildings or hard stuff its just slow as hell compared to bullet.Maybe for some internal parts to give more granular feel.


I mean there is a whole section on the frontpage advertizing MPM for destruction. So as slow as it might be, there must be a viable way to work with solid stuff.



None of these shows how to mesh the MPM particles back to solid models though.
Edited by kodra - July 12, 2024 10:26:46

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Hi there,

I'm currently working on an MPM Masterclass that will hopefully answer most of your questions .

For the Fruit Smash scene it's using the usual points -> vdb -> polygons workflow. You just need to properly transfer the uvs and rest attributes and you should be good to go. For the building, the setup is a little more involved since you post fracture the hires geo based on the last frame of your mpm simulation. Then you can use the deformation gradient F to transform the post-fractured pieces to the right place.

Hold on tight, answers are coming your way!
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Its here, thanks Alexandre!

https://youtu.be/0jJXTHjLW8g?si=Ps7L1tGwx8aUeXa0 [youtu.be]
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Hello, great Masterclass helps a lot. One question I still have is there any reasonable way to combine the results of the mpm with other solvers, like vellum, bulltet or flip
the onlu way to I can imagine right now to get interolated colliders woult be the points, but the mere amount seems a no go
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at least with flip, it works fine.

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mpm_flip.mp4 (10.0 MB)

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sanostol
at least with flip, it works fine.
nice, looking forward to more tests like this. thanks for sharing!
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