nParticles issues please help.

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Old 02 February 2013   #1
nParticles issues please help.

Hey all,

Iím a student studying VFX and as part of my 3rd year of study we are required to pick a specialty and complete monthly challenges.

I have chosen to specialize in Dynamics and my first monthly challenge was to create a simulation of cereal falling out of a container and into a bowl.

This is a link to the reference footage I shot for the brief: http://youtu.be/FQ5P3nSqj7Y

Iím working and have run into a couple of issues creating the simulation.
I have picked the nParticle system.

For my RnD I have mucked around with ball emitters, points (then instancing geo on the balls/points) and geo.

I found creating each individual piece of cereal and converting them to nClothís was far too resource intensive on my poor little system.

When using Balls or points and instancing I find that each geo collapse in on its self.

Initial state

Broken

Playblast test with http://youtu.be/aLHux0OSFNk

Next month I will be adding in Milk to the simulation so if anyone has any ideas or can offer any assistance it would be greatly appreciated.

Thanks,

Sam
 
Old 02 February 2013   #2
Perhaps you don't have self collision on the particles, or perhaps the particle radius is too small. If the gravity is strong then the self collisions might fail if the substeps are not high enough, but I doubt that is your problem.

I've attached a simple scene that does roughly what I think you want.

I started with the ball preset then instanced a torus to the particle system. Next I enabled computeRotation on the particle system.

Under the instancer tab I set enableAllDataTypes true then set Scale to radiusPP. This will resize the object to the particle size... you can scale the original object so it just fits the particle. The rotationType is set to rotationPP so the instances show the particle rotation. Note that this rotation is for spheres, so the torus shapes on the ground will not settle flat. (a tradeoff when using this method)

Then I just enabled the ground on the nucleus node and make a box a passive collider.

To keep the particles from rendering I enabled intermediateObject on the particleShape.
Attached Files
File Type: zip cerealEmitter.zip (8.6 KB, 18 views)
 
Old 02 February 2013   #3
thanks for the reply Duncan!

I thought the same thing initially and played around with the collisions on the particles and the radius but had absolutely no luck. I had to reduce the substeps as my computer was struggling to deal with everything, however I didn't adjust the gravity so this could possibly be a factor that was causing my problem.

I'm comparing my scene to the one you uploaded to try and work out what i have done wrong when i work it out and have everything completed I will upload a new version

Thanks again for your help I hope it wasn't to much trouble!

Sam
 
Old 02 February 2013   #4
The scene was a fantastic help and I have learnt alot from it!

Duncan I can see what you mean when you said
the torus shapes on the ground will not settle flat. (a tradeoff when using this method)


If I did want them to sit flat what would the best way to achieve this be? Would I be better of using geo and converting it to nCloth? or is there a more efficient way? (I don't want to bother you to much but if there is something I can research myself I'm more than happy to look into it further if someone can point me in the right direction.)

Here is an updated playblast of the system: http://youtu.be/u_f3c1Wvhjc

any feedback is more than welcome and greatly appreciated!

Sam
 
Old 02 February 2013   #5
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