johner
johner
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Since Jul 2006
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Recent Forum Posts
Otis / Otto muscle sim collapses on first frame Nov. 28, 2025, 5:25 p.m.
We've seen cases where the geometry created by the Muscle Transfer process contains very, very small tetrahedra (on the order of 1e-15), which can lead the solver to become unstable with floating-point precision.
One thing to try is just delete any incoming tets below a certain threshold. They are so small they often make no difference in the appearance of the sim. Try a Primitive Wrangle with the following code:
And put this below both the incoming muscles and fascia setups, as in the green "remove_tiny_tets" nodes below:
EDIT: Actually all the outputs from the `muscle_setup` node should likely be re-routed through `remove_tiny_tets`.
One thing to try is just delete any incoming tets below a certain threshold. They are so small they often make no difference in the appearance of the sim. Try a Primitive Wrangle with the following code:
if(primintrinsic(0, "typename", @primnum) == "Tetrahedron" && primintrinsic(0, "measuredvolume", @primnum) < 1e-10) removeprim(geoself(), @primnum, 0);
And put this below both the incoming muscles and fascia setups, as in the green "remove_tiny_tets" nodes below:
EDIT: Actually all the outputs from the `muscle_setup` node should likely be re-routed through `remove_tiny_tets`.
Nvidia rtx 4090 driver issues? Feb. 23, 2023, 1:12 a.m.
The Houdini 19.5 Production Build of 19.5.534 includes the following change which should resolve the issue with Vellum pressure constraints and the 4090. This fix has also been backported to the daily 19.0 build.
Rewrote the Pressure constraint in the Vellum Solver to make it deterministic on GPUs at high constraint counts, as well as to avoid hanging that was occurring with the latest Ada architecture GPUs from NVIDIA (e.g. 4090).
Vellum Solver OpenCL errors Oct. 25, 2022, 9:36 p.m.
Yes, it's an issue with the latest NVIDIA driver, which changed some things about the OpenCL compiler. This forum post is from people who ran into it:
https://www.sidefx.com/forum/topic/86887/ [www.sidefx.com]
We've fixed it for the daily builds, but there are ways to workaround if you're stuck on a production build.
https://www.sidefx.com/forum/topic/86887/ [www.sidefx.com]
We've fixed it for the daily builds, but there are ways to workaround if you're stuck on a production build.