WIP by O'Neill

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shaun_michael
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WIP by O'Neill

Postby shaun_michael » Thu Aug 02, 2007 4:15 pm

Whats your max substeps set to? In other words can you afford to lose a little accuracy in return for a faster simulation time?

Shaun


O'Neill
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Joined: Thu Jun 21, 2007 2:02 pm

WIP by O'Neill

Postby O'Neill » Thu Aug 02, 2007 4:28 pm

Can substeps be changed during a simulation? The first 50 frames were simulated with the default 333 substeps, but then (without resetting) I changed it to 40 substeps. Do I have to reset the scene in order for the new substep changes to take effect?

shaun_michael
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Joined: Sun Sep 10, 2006 8:04 am

WIP by O'Neill

Postby shaun_michael » Thu Aug 02, 2007 4:34 pm

No, you dont need to reset the scene for the effect to take place in the scene. Are you noticing a clear difference in the sim times per frame now?

Shaun

O'Neill
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Joined: Thu Jun 21, 2007 2:02 pm

WIP by O'Neill

Postby O'Neill » Thu Aug 02, 2007 5:09 pm

Its hard to tell. Ive got 3 emitters with a total of 210,000 particles. My machine is a AMD 1 Ghz, 768 RAM. Its not exactly fast, so its hard to tell any difference in simulation time.

O'Neill
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Joined: Thu Jun 21, 2007 2:02 pm

WIP by O'Neill

Postby O'Neill » Thu Aug 02, 2007 9:43 pm

Ok, I can see a definate improvement now. I took the substeps down to 30, and it seems to be ok. I can tell that the simulation for each frame is quicker than before. Im going to let it run tonight (overnight) and ill see how many frames it simulated in a period of about 8 hours.

shaun_michael
Posts: 4766
Joined: Sun Sep 10, 2006 8:04 am

WIP by O'Neill

Postby shaun_michael » Fri Aug 03, 2007 9:13 am

Be careful though with a setting that low that your collision events are happening properly. At that low a substep level often you get penetration of particles through geometry. But you should see an improvement, even on your relatively low-spec machine.

Good luck,

Shaun

O'Neill
Posts: 76
Joined: Thu Jun 21, 2007 2:02 pm

WIP by O'Neill

Postby O'Neill » Fri Aug 03, 2007 2:47 pm

I let it simulate overnight, and it only simulated 12 frames in 9 hours. The collisions look ok. I didnt see any particle penetrations, or leaking. I may have to come up with another idea... or just shorten this one from 21 seconds, to around 5 or 6 seconds.

shaun_michael
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Joined: Sun Sep 10, 2006 8:04 am

WIP by O'Neill

Postby shaun_michael » Fri Aug 03, 2007 6:38 pm

Wow. Have you got your scene optimised as much as possible? Only the geometry that's absolutely necessary, killer daemons to catch errant particles etc?

You might also want to look into doing the simulation using the command line (instructions in the docs).

Seeing as you're using what would be considered a slow machine, lightening the scene a little and optimising the cr*p out of it would seem the most sensible idea to hit your dealine.

Shaun

O'Neill
Posts: 76
Joined: Thu Jun 21, 2007 2:02 pm

WIP by O'Neill

Postby O'Neill » Fri Aug 03, 2007 7:12 pm

Yeah. I only have geometry in the scene that has to interact with the particles. I have 3 emitters in the scene, and they all have the same settings.

Resolution - 6
Density - 1250
Surface Tension - 35
Interior Pressure - .5

I think im going to reset the scene, and only use one emitter. The idea I have is a large water tower sitting on the side of the road. The overflow pipes open up and unleashes a massive amount of water (or in my case, some milk) onto the road, field, and the bus in the footage splashes through it.

I think if I use only 1 emitter, and scale it up just a little, I might be able to simulate all 500 frames before the deadline.


On a side note, I found a realflow script on the internet that creates a spray when particles hit a surface. I would like to use it, but I have no knowledge of scripting. Where can I go to find out how to use this particular script for my scene?

shaun_michael
Posts: 4766
Joined: Sun Sep 10, 2006 8:04 am

WIP by O'Neill

Postby shaun_michael » Fri Aug 03, 2007 7:41 pm

Can you point us to the script and we can take a look at it and perhaps tell you how to use it. Meanwhile, if you do a search for the foam script on this forum there's plenty of chat about how to use that one which may well give you some ideas.

Shaun


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