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Simulation resume/set initial state ?


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If a sim crashed, can I supply a simmed bgeo (particles) frame as an initial state so it could continue with the same settings, or others, based on that original ?


Or another example : I have a fast moving fluid in a splash, that in the next shot is seen from another angle just dropping from the last known position.

In the initial shot, high samples, low gravity was used.

In the second one, I don't need that many samples, and I need higher gravity.


An initial state by supplying a start frame could solve a lot of problems..


Is this already somewhere in Houdini and I've missed it ?...

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on the dopnet itself it has an option to save an explicit cache.  This will output each frame as a .sim file so you can resume from your last frame.  There is an option as to how many frames to keep, this is important because .sim files can get to be really big. If you have this checked on, you can just re-sim from that frame without any trouble.  If you write a specific frame you want to use as your initial state, it will have to be a .sim file as well, and you would select the specific .sim file on the dopnet itself.

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  • 2 weeks later...

right now I am specifying the frame as a file input in the flip fluid node that pipes into the flip fluid solver, and caching the resulting particles as bgeo (is this wrong ?)

as I see it, if it crashes, I can specify the last bgeo as the new input, change the frame range and start again.

right now I am sculpting a shape out of particles, with custom velocities, and feeding it into the flip fluid node...


it is along the same lines that your solution draws, so I was wondering what is the difference between doing it in the flip fluid node and at the top of the dop network....

also, why would I keep more than one frame (how many frames to keep) ? doesn't the sim uses the atributes from the last frames to advect for the new frame ?...

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.bgeo is not a .sim file. bgeo just saves out the result while a .sim keeps all the data the sim uses (velocities, samples and so on).  So unless I am mistaken, if you have only chached out bgeo, you can't just resume simming I'm afraid. :/

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@Peon : could you link me up to a more detailed description of the difference between them, or elaborate a bit more ?


At the moment I am saving out the particles as bgeos in a separate file, with a custom velocity, and using the "file" option, (instead of SDF from geo, or something else) in the flip op that is piped in the flip solver.

And it seems to work, as they are advected just fine according to their velocities - just as I was expecting...so why is this the wrong approach ?

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