Particle resimulation slow down problem when stoping and restarting.

[jstrob]

I am trying to slw down an explosion with 0,25 factor. The first thing I noticed is it seems to take longer to slow down than to simulate. The simulation took 3 min by frmae max and the resimulation take more than 10 minute a frmae on my main computer and more than 1 hour on another computer with less ram.

Also when I stop the simulation and then restart it later there is a shift in the animation. the result doen't fit exactly with the previous frame so it seems like I have to do the slow down in one go. (I also switch computers when doing so).

Is it expected behavior?

[Svetlin.Nikolov]

Hey,

It shouldn't be like that. Can I have a look at shots of your Resimulation and Input panel settings? Are you using the Time-Scale on the Dynamics panel?

Another thing - what kind of channels are you simulating? What are the particles doing in your scene? I would imagine one would do a Grid Resimulation for an explosion..

[jstrob]

I noticed that the slow down was more toward the end, after I stop and restarted the sim at the frame where it was ended.

The biggest problem is that when I stop it and restart (not pressing the pause button, but the stop button) the resim will not fit with the preceding resim.

[Svetlin.Nikolov]

Couldn't reproduce it here with a new scene - I suspected the animated grid size could be the cause, but all works as expected with these options.

Is it still the same with a latest nightly? If so, I'm gonna have to ask you if you could share your scene - seems like something more specific...

[jstrob]

can I have your email to send you the scene please?

Now My resim just can go on past frame 510 (out of 575). The slow down starts around frame 400 where it goes from 2-3 min to 10 minutes a frame and then around frame 500 it takes 1 hour a frame and at frame 510 it was calculating all day and I just stopped it.

I will render my explosion now and then install the latest nightly to see if the behaviour is the same.

[jstrob]

Here is a clue about why it took an hour around frame 500 of the slow down resim.

the result started getting buggy at frame 506:

I will redo that sim with latest nightly to see what happen.

[Svetlin.Nikolov]

The image explains it - I've found an issue that will bug the velocities during slow down resim in the nightlies for the last week or so. The fix will be in for Tuesday's nightly build. Thanks very much for signaling us!

[jstrob]

ok cool thanks!

I posted the working part of the animation there: http://forums.chaosgroup.com/showthr...396#post668396

[Svetlin.Nikolov]

Hope your times will be much better tomorrow What is your grid resolution?

[jstrob]

At the end I got 754 million cels.

[Svetlin.Nikolov]

Wow! So this is about as much detail as you could possibly get.

[jstrob]

With 65 GB of ram yes. But at 2-3 minutes a frame it's quite fast to simulate. Slowing down is a bit longer but perfectly predictable at least. Now I want to buy more ram! My system can support 768GB max. I will check what my wallet can support!

[jstrob]

Can you confrim if tuesday's nightly should be ok about the velocity when slowing down?

[Svetlin.Nikolov]

Yup, Tuesday's (26357) has the issues from last week fixed. How is the speed with your scene? Since you're pushing the limits, it may still not behave as expected - please ping us if so

[jstrob]

What do you mean by "the speed with my scene"? I haven't instaled the new build yet. I'm now working on something else for a few days.