Mparticle collisions stop working on file open

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Old 06 June 2013   #1
Mparticle collisions stop working on file open

I have had a recurring problem with my files when using mparticles. I get my system set up, I get my collion objects setup, everything is working fine. I save the file. When I open the file again the collision objects no longer work, I have to delete the pflow collision shape, add it back again, reactivate it, then delete my MassFX Collision node in particle flow and add it again and relink the collision objects. After I do this it works just fine... until I save the scene and then open it again.

This happen in 2013, and it is also happening in 2014.
Old 06 June 2013   #2
Some more information on the problem. If I open up the scene it will work properly my first time running through the scene, however if I go back to frame 0 and run the scene again, my collisions no longer work.

If I create a new driver in my Mass FX world the scene then works properly again.

I've tried this on several machines and it is the same situation on all of them.
Old 06 June 2013   #3

Here is a video showing what is going on. I open the file, I play it the first time and it works properly. I go back to frame 0 and play it again and it is no longer working. If I add a new world it then works again fine, but if I then save the file and open it again it does the exact same thing.
Old 06 June 2013   #4
Hmm interesting, I usually get a fail on first playback after I make some adjustments.

What are your subframe sampling steps set to? If it is default of 2 try raising the value.

Still nothing, remove all or the mP Worlds (VP Helpers) unwire and delete the PF Source global node and recreate them. Try new PF Collision Shape mods too (btw what mode are they set too?). Something maybe glitchy.

It is a good rule of thumb to keep any standard/mP operators above the mP World. The only things that should go below it are mP Tests, some Standard Tests, Data Ops. that require evaluation after PhysX, Display and/or misc. ops.
poof ~>Vimeo<~
Old 07 July 2013   #5
I tried rebuilding the scene from scratch and it is still doing it.... I would say it's a problem with my machine, but it does this on my coworkers machine as well.
Old 07 July 2013   #6
Samples are set at 4 which works fine, until I reopen the scene. At that point it doesn't matter how high I raise them, it doesn't catch the particles until I add a new world. It's funny because you can tell it's still doing something as the particles still disperse a bit as they pass through the collision object.
Old 07 July 2013   #7
Does the type of unit effect the particle simulation? I have the scene built in mm, my coworker thought it might help to move to generic units.

Also could it be a scale issue of the scene. It's not tiny, but it is a bit small. My emitter is 30mm by 30mm if that helps you know the size of my scene.
Old 07 July 2013   #8
Extreme scales either to big or small can be detrimental and as long as you only adjust your display units and not your system units you should be ok.

If you open the file and say adjust the emitter speed and play it back a few times does it still not work?

This is pretty strange. Was the original pf system built on PF Tools Box#2 or the max 2013 SAP particle extension?
poof ~>Vimeo<~
Old 07 July 2013   #9
I tried that, same thing. Here is a link to the file if you want to play around with it.

Open it up and press play, notice how the particles behave, now go back to frame 0 and press play again, notice how they now behave completely differently. However if you replace the massFX world they will behave like they did when you first opened the file, they will continue to work the same, that is until you save the file and reopen it again, and start the whole process over. I've exausted my knowledge and tried everything I can think to try. I've rebuilt the collision objects, cut them up into multiple collision objects, rebuilt the particle flow node, messed with the scene scale, tried different collision geometry, tried different collision modes instead of geometry, etc..... it does the same thing no matter what I do. I have had this same problem on other scenes, and the fact that no one else seems to have heard of this makes me think I am doing something wrong, but for the life of me I can't figure out what.

The scene was built in 2013.

Old 07 July 2013   #10
I also tried this in 2014 and it's the same thing.
Old 07 July 2013   #11
Hmm, something was definitely wonky. I merged to a fresh scene and excluded the ParticleView and the PF Engine from the merge (max will automagically create new ones) the scene seems to work fine now.

Oh and I brought the Subframe Factor up to 32 those particles are traveling pretty quick and changed all the PF Collision Shape mads to Geometry.

Ghost in the machine. Try the attached and see if it works for you.
Attached Files
File Type: zip (44.0 KB, 2 views)
poof ~>Vimeo<~

Last edited by JohnnyRandom : 07 July 2013 at 09:07 PM.
Old 07 July 2013   #12
It's working so far, thanks. What concerns me though is that other scenes I have built that had nothing to do with this have shown the same issue... Hopefully working in 2014 from here on out will fix whatever issue was happening.
Old 07 July 2013   #13
Yeah, growing pains. This stuff was just integrated into max and there is bound to be some strangeness going on. max2014 SP1 does address a few pflow related issues.
poof ~>Vimeo<~
Old 07 July 2013   #14
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