Nparticle rotation on emission?

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Old 09 September 2013   #1
Nparticle rotation on emission?

Hey guys,

I have a question about adding rotation to an Nparticle emitter. How would one go about emitting Nparticles directionally with rotation already applied when the particle is emitted. For example, let's say you needed dynamic wood chips spitting out of a wood chipper...

Expressions on Instances are math driven so they wouldn't behave dynamically so my guess is that the nParticles themselves would have to have rotation on them that drive the instances?

Would some sort of field be needed to drive the particle rotation?

brain twister

*EDIT seems like I can pick up rotations off the initial emission if I have self collide on because they bounce off eachother but I'm sure there's a better way.

*Semi solved. If I bounce the particles off a plane in the opposite direction, the particles will have some nice rotation when I take the rotation friction down a bit.

Last edited by rcronin : 09 September 2013 at 07:43 AM.
 
Old 09 September 2013   #2
Bumping this thread, since I was trying to achieve more or less the same thing a few days ago and couldn't really get it to work satisfactorily.

I was emitting nParticles from DMM fragments, trying to simulate smaller debris. Keying "Tangent & Normal Speed" (I think that's what they're called) on/off provided a little variance but did not really work out too well since the resulting rotations etc, if any, were really weird and the particles emitted later tended to just fall flat to the ground upon emission.

Also, I couldn't get the particles to pick up the initial directional velocity of the emitting fragment. Not sure if that is at all possible.

Cheers!
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Old 09 September 2013   #3
Figured I'd also bump this thread. I'm pretty new to Dynamics in Maya, but not in physics at all...

...and I cannot for the life of me get my particles to spin. I've tried expressions, userVectorsPP, and of course "Compute Rotation", but alas no spin at all in my particles or my instances, yet.

I've just made a simple sphere, parented a short straight curve to it to see if it can spin. So far, only spins I can get are from collisions...

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Old 09 September 2013   #4
You can give your particles an initial rotation by using angularVelocityPP. Just write a creation expression like: "nParticleShape1.angularVelocityPP = << rand(-2,2), rand(-2,2), rand(-2,2) >>;" and they should spin upon emission.
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Old 09 September 2013   #5
Yes, that's what they want you to think. It would make sense, and appears to work but no spin is apparent whatsoever, and no physics is being calculated along those lines. It's certain I'm doing something wrong, I've made stuff spin before!

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Old 09 September 2013   #6
What I did was activate "Compute Rotation" under the rotation tab and write the expression above to set angularVelocityPP. In the instancer tab I set rotation to rotationPP.

Maybe you would like to check my scene (Maya2014) https://dl.dropboxusercontent.com/u/99420482/angVel.mb (right click save link as).
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Old 09 September 2013   #7
MCGrund you rock!

Thanks, this needs to be added to Google somehow so that it shows up in searches heheh.

p.s. Infernal the 3 steps are 1 - create the expression 2 - in your particle shape turn on compute rotation under the rotation tab 3 - under rotation options in the particle shape set the rotation drop down menu to rotationPP

Thanks a bunch.
 
Old 09 September 2013   #8
Thanks a lot, MCGrund! I'll check that out.

Cheers!
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Old 09 September 2013   #9
Sure you're welcome!
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Old 09 September 2013   #10
Thanks a million, MCGrund! I've got some spin now, but it's way out of control. Just need to tweak my settings and see what I can come up with!



I'm involved in a physics project, starring actual physics and giving photons mass and spin. I have a long way to go to simulate this math without any fudges, pushes, or consensus "science" BS, so I've gotta keep it as clean as possible. Thanks for your help in this step!
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"Like stone we battle the wind... Beat down and strangle the rains..."
 
Old 09 September 2013   #11
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