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Fireandsmoke

Compensate for slowing FPS/Timescale

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I've been playing for days and days trying to slow smoke sims for some nice particle advections.  They need to be very slow, so the process I've been trying to use is either reducing the timescale, or cranking up the FPS of my timeline.  At these slow speeds, it is not practical to find the "look" of my sim, I need to look dev at 25fps, and then slow that version down.  But by then slowing down the sim via timescale or FPS, only rarely do I get a result I want.  Is there settings with the solver or DOPnet that I need to be adjusting to compensate for the slower speed?  Most of the time, a beautifully turbulent and dynamic sim at 25fps often just turns into a hopeless blob at 200+fps or 0.1 timescale.  Would love some input on this..  (PS.  Im still on 16.5 for now, so the retime node is not an option).  

 

Thanks

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Check out the volume retime HIP file at this location.

https://github.com/qLab/qLib/tree/dev/examples

To leverage this technique you must have a vel field in your output.

Basically simulate at a normal speed then use that setup to slow it down.

Edited by Atom

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On 01/11/2018 at 12:17 AM, Atom said:

Check out the volume retime HIP file at this location.

https://github.com/qLab/qLib/tree/dev/examples

To leverage this technique you must have a vel field in your output.

Basically simulate at a normal speed then use that setup to slow it down.

Thanks Atom, this looks good. 

Have you used this setup before?  

Ive tried copying this retime setup into my own pyro sim but its not working as in the original .hip, just plays back both at the same speed.  

EDIT:  Just noticed that this actually involves the installation of a custom asset library.. then it will work..

Edited by Fireandsmoke

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For my own understanding, I'd really like to know why changing the timescale parameter changes the look of the sim so much?  I thought its function was to scale the time base of everything inside the solver, so why does it then cause such huge change - a basic smoke sim at timescale 0.1, 1 and 5 are all going to look completely different... which makes it kind of useless.    

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On 2018-11-29 at 6:01 AM, Fireandsmoke said:

For my own understanding, I'd really like to know why changing the timescale parameter changes the look of the sim so much?  I thought its function was to scale the time base of everything inside the solver, so why does it then cause such huge change - a basic smoke sim at timescale 0.1, 1 and 5 are all going to look completely different... which makes it kind of useless.    

I'm not a 100 % sure this is the only reason, but if you open up your solver and dive inside, you can see that not all the Micro solvers inside are linked to the timescale parameter. So when changing time scale some of your micro solvers will still run at time speed 1

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