Request: Decouple HiRes Wavelet Sim from Base Simulation

[GottfriedHofmann]

It seems every other smoke simulation has the option to decouple the base simulation from the hires. This way getting a desired look that involves high resolution does not require to simulate the base again as well. It even allows to apply hi resolution to just one frame in the simulation which is a lot faster when doing look development than simulating the entire thing again and again and again.

[sebbas]

Yes, I want this as well!

I've been thinking about how to achieve this and it seems the only way to get it working is to not use the Blender internal "Pointcache" and instead use a custom built cache with Mantas I/O functions. This approach would store all grids separately in their own files and not bunch all frame data into one single file as the Pointcache currently does.

This would have the advantage that:

• we can finally decouple the high-res sim. Since all cache files are written individually we can also generate/discard the high-res files on their own
• it fits in nicely with the idea of breaking down the simulation in general (generate/discard not only low-res and high-res simulation files independently but also mesh and secondary particles cache files)
• importing simulation files that were previously written with Manta should be possible (esp. interesting for Nils)

I briefly covered the "Manta .uni file" export during GSoC but didn't go ahead with it. I'll now give it another shot.

[GottfriedHofmann]

Go for it! Decoupling Particle Sim from Meshing is something I wanted to ask for as well :)

[thunil]

Hi Sebastian and Gottfried,

yeah, it would be neat to allow for an iterative workflow for gas as well as liquids. Theoretically, it's not a big problem, mantaflow does support this already, and there are some examples scenes for it. I think it's more tricky for the current Blender implementation, and the user interface. I'm not sure it makes sense to add a quick "hack" here, or rather wait and to a nice re-implementation of the data flow.

Sebastian - do you have time to chat about this, e.g., next week or so?

Cheers, -> Nils

=== Technical University of Munich , http://ge.in.tum.de/ ===

On 8. Mar 2018, at 00:26, Gottfried Hofmann [email protected] wrote:

Go for it! Decoupling Particle Sim from Meshing is something I wanted to ask for as well :)

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[sebbas]

Hi Nils, yes, let's do that and arrange everything via email.

And yes, a quick "hack" is not what I am looking for either. I just think for the cache to be more flexible it might have to look more like the current Elbeem cache.

Gottfried, is it just me or is baking smoke really not UI friendly. The fact that everything freezes once you fire off a high-res sim and you can hardly cancel it really freaks me out sometimes ..

[GottfriedHofmann]

Nils, the freezing of the UI is a really huge issue. In other program one can still scrub the timeline and have a look at the sim as it is developing, including changing the way it is displayed in the viewport. That is really helpful.

[thunil]

Hi Gottfried, ah good that you mention it... Yes, Sebastian and I should also discuss that some more. I think it should be possible to de-couple the mantaflow thread, if I'm not mistaken mantaflow is running in an own python environment anyway. Then it would mostly be about having a lock object for data transfer. Alternatively, doing a data transfer via files written to disk could be even simpler.

Cheers, -> Nils

=== Technical University of Munich , http://ge.in.tum.de/ ===

On 9. Mar 2018, at 16:08, Gottfried Hofmann [email protected] wrote:

Nils, the freezing of the UI is a really huge issue. In other program one can still scrub the timeline and have a look at the sim as it is developing, including changing the way it is displayed in the viewport. That is really helpful.

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