lifespanPP=-1 doesn't work

[docaberle]

lifespanPP = -1; doesn't seem to work. I've included the file and a one minute video showing the problem. The only odd thing I've done I believe is knock the collision intensity down so the particles wouldn't move when they collided. Maybe that has something to do with the particles not disappearing when hit.

[docaberle]

Started over again with a new scene, made a box and filled it with particles. Then under expressions/after dynamics set:

nParticleShape1.lifespanPP = -1;

That's it, and all the particles from the box just fall with gravity as you'd expect. But the expression should delete all the particles after the first frame I would think. Am I missing something here. Oh yes, also changed Lifespan Mode to LIfespanPP Only.

Suggestions? Thinking there's a bug or I'm just not doing something right.

[slimboJoe · Accepted solution]

It's because the particles you are trying to kill have no associated emitter.  The lifespanPP won't work without the an emitter being active, as in actively emitting particles.  I believe it's a nasty bug.

Try this.  Create an new emitter.  Delete the particles that get created with it.  In the Dynamic Relationship editor, link the nParticle1 particles to the new emitter.  Position the emitter out of the way, off to the side, anywhere really.  Now, as long as that emitter is spewing forth, your particles will now magically respond to the lifepsanPP attribute.

If you were to animate the emiiter turning off, your particles will no longer respond to the lifespanPP when the emitter rate gets to 0.  It's a fairly major bug.

I can send your altered scene back if this does not make sense to you.

[docaberle]

You're absolutely right. Thank you. I tried the same thing in Maya 2016 Ext 2 and I can kill the particles no problem. I'll just work in 2016 instead until the bug gets fixed. Hopefully they'll see this and get it corrected. Thanks for pointing it out.

[slimboJoe]

No problem.  I wish I would have tried going back to 2016.  Would have saved me hours of troubleshooting.

I was using 2016 Extension 2 SP1.  I tried 2017 Update 3, but got the same bad results, so naturally I assumed this has been a bug for awhile.

I've got an open ticket on this.  I'll update as a recently introduced bug.

[slimboJoe]

Try switching to DG mode instead of PARALLEL mode.  Seems to make the particles work correctly.  Not cool, though.