Hello, ive been running into an issue with the mpm solver when using it on a renderfarm. depending on the machine, the results will be different. there is a major difference between the results on a machine running on the cpu, and running on the gpu. but also between 2 very similar but not identical gpu machines, i noticed minor differences in particle positions.

the documentation mentions a checkbox for "Deterministic Particle-to-Grid Transfer": https://www.sidefx.com/docs/houdini//nodes/sop/mpmsolver.html [www.sidefx.com]"

however i can not find this checkbox anywhere on the node, and not even when unlocking the sop container and checking the actual solver inside, there is no such parameter.

furthermore i would expect this to be enabled by default anyway, as deterministic results are kind of the bread and butter of vfx are they not?

Has anybody encountered similar issues or even a solution, other than ensuring that you always run your simulation on the same machine, which, lets be real, is not realistic in a real production environment...

thanks

Edit: houdini version is 20.5.332

good for you lmao but heres what my node looks like

what build verison are you using?

i even checked the parameter interface for any inisible parameters, or parameters that only show up when certain other conditions are met, but theres nothing...

Welcome to the OpenCL land. Same issues as with Vellum Solver.

janderfischer
Edit: houdini version is 20.5.332

That option was added in 20.5.361

20.5.361
Adding deterministic particle-to-grid as the default transfer algorithm for MPM. This change accelerates the whole solver by 230% on average when benchmarked against the examples from the mpm masterclass using a Nvidia 4090.

Tue. September 17, 2024

here i was thinking we finally upgraded to an up-to-date build at my company after working in 19.5 until now... well, thanks for the reply, im just glad im not crazy or blind

cheers!