SteveSayer Posted July 31, 2015 Share Posted July 31, 2015 Folks, this issue is driving me crazy. I've got a scene in which one POP solver creates some primary particles, and then those particles leave trails of other, secondary particles behind them. I'm playing the scene at a non-integer frame value (0.5 frames). The POP solvers are all using 1 substep. But playback is very inconsistent! Sometimes the secondary particles just don't show up during playback. Sometimes they do. It's maddening. I'll play the scene a dozen times and only the primary particles will be visible. Then I'll toggle a bunch of settings--like substeps, DOP network visibility, particle display mode--and sometimes, seemingly at random, the secondary particles will start showing up properly. But I can't for the life of me figure out why it's so inconsistent. Nor can I figure out a bulletproof, reliable series of changes to make things work properly. I've tried sourcing the secondary particles through DOPs as well as through SOPs, The same problem occurs. I'm at my wit's end--it's very difficult to be productive when half the time my scene won't play properly. Is this a known issue? Can anyone suggest a workaround? Things improve if I cache the original particles first, but that isn't exactly the most efficient workflow when I'm trying to tweak behaviour. Thanks for any suggestions. Quote Link to comment Share on other sites More sharing options...
Skybar Posted July 31, 2015 Share Posted July 31, 2015 Does it work if you use integer frames? Why do you need it to be non-integer? Quote Link to comment Share on other sites More sharing options...
SteveSayer Posted July 31, 2015 Author Share Posted July 31, 2015 Hi, Skybar. Thanks for the reply. No, switching to integer frames doesn't solve the problem. I'm using the 0.5 playback rate because I'm using the 'all points' emission type, and I need twice as many particles to be emitted as I'd get if I used integer frames. I experimented with a few approaches, and this seemed like the cleanest and most reliable way to have extremely precise control over the number of particles emitted. Quote Link to comment Share on other sites More sharing options...
Skybar Posted July 31, 2015 Share Posted July 31, 2015 Not using integer frames will probably trickle down to further problems down the road, just saying. Even if it works now, I'd look at other ways before it becomes a habit. Also just post your hip, it's hard to guess whats wrong. Quote Link to comment Share on other sites More sharing options...
SteveSayer Posted July 31, 2015 Author Share Posted July 31, 2015 Thanks. Yeah, I'll try to post a pared-down version of my hip file soon. I just wondered if it was something that was a known issue and could be flagged quickly by someone with more experience than I. It seems to me that for fast-evolving effects it would be pretty common to use oversampling and/or non-integer frames for increased control... it'd be surprising and frustrating to find out that such basic functionality is missing. Thanks again. Quote Link to comment Share on other sites More sharing options...
Guest tar Posted July 31, 2015 Share Posted July 31, 2015 .. it'd be surprising and frustrating to find out that such basic functionality is missing. Yep - it's usually user error or lack of skills tbh Quote Link to comment Share on other sites More sharing options...
anim Posted August 1, 2015 Share Posted August 1, 2015 (edited) just note that changing the playback to integer or not integer frames doesn't have any effect on precision of your sim the substeps do however what can affect the look of your dopsim during non-integer playback is Interpolate Display Data checkbox on your dopnet, usually it's better off (especially with dying particles, volumes, etc.) Edited August 1, 2015 by anim Quote Link to comment Share on other sites More sharing options...
SteveSayer Posted August 2, 2015 Author Share Posted August 2, 2015 Yep - it's usually user error or lack of skills tbh Hah. Point taken, marty--and probably quite correct in this case (read on). just note that changing the playback to integer or not integer frames doesn't have any effect on precision of your sim the substeps do however what can affect the look of your dopsim during non-integer playback is Interpolate Display Data checkbox on your dopnet, usually it's better off (especially with dying particles, volumes, etc.) Good note, Tomas, thanks. I had been keeping my playback rate in sync with my DopNet substeps, as I found I was experiencing (other) errors otherwise. I'll look into the Interpolate Display Data route instead. Thanks again. As to the inconsistent playback... I think I tracked it down, at least partway: I had been using an expression to control the Impulse Count of the POP Source creating the trailing particles. When there are more primary particles, I needed a higher volume of trailing points being emitted in total. So this expression factored in the point count of the primary particles. To do this I was using npoints() on the primary particles' DOP I/O node in SOPs. For some reason, that seemed to be causing the problem (admittedly not sure exactly why--any thoughts?). Replacing the expression with a constant restored correct emission behaviour. So, I dug a little deeper to find the appropriate expression to get the pointcount of a particle object directly in DOPs. Since switching to that workflow, playback has been consistent--touch wood! I'll keep an eye on it and check back in if I figure out anything new. Thanks for the help, folks. Quote Link to comment Share on other sites More sharing options...
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