Jump to content
Chats

Process POP Wrangle only once per frame in a multi sub-step POP solver?

Recommended Posts

Hey there, I have a situation where I am using a POP wrangle inside a DOP network to set some attributes on my particles using a fairly expensive volumesample() VEX call, that is sampling a volume from another SOP network.
The problem is I have up to 10 sub-steps in the sim but only need that POP wrangle to run and set my attributes once per frame, not at every sub-step within the frame.

Is there any way to tell the POP wrangle to only execute on the first sub-step of the simulation frame?
Or more broadly, is there a way to read in my SOP volume geometry to my DOP network evaluated at a discreet time that I specify (ie. at a whole integer frame) so that Houdini doesn't re-cook the incoming SOP geometry at every sub-step, but just the one time within that frame?

I tried setting this expression on the POP wrangle Activation parameter, that would only evaluate to 1 on a whole integer frame but that didn't work (the referenced SOP network still cooks at every substep):

$T==(($F-1)/$FPS)
(this evaluates to 1 on integer frames like 1, but evaluated to 0 on inbetween frames like 1.5)


I have used proprietary fx tools in the past that allowed a geometry data graph node to be referenced and evaluated at any specified time, and I was wondering if there is a way to do the same in Houdini?
I had a quick look at the SOP Geometry node in the DOP network, which looked promising as it has a time parameter that can be set, but I couldn't get it to read in my geo into DOPS, I'm sure I'm just not using it correctly..

I hope my question isn't worded too confusingly, I'm still new to the software and loving it :)
Thanks for any help!

Share this post


Link to post
Share on other sites

You could try the Gas Intermittent Solve DOP.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×