nparticle meshing

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Old 01 January 2013   #1
nparticle meshing

im working on a water splash animation. no time or budget for realflow so trying to use nparticles. im finding the meshing very jittery especially when using peak node from soup.

anyone have some pointers in how to make it more useable?
Scott Turner
Old 01 January 2013   #2
Lots of particles, plenty of surface tension and some way of keeping particles together (this is my biggest problem), nConstraints aren't very effective when working with so many particles.

Finally dont expect anything like Realflow, sorry this is from my experience maybe somebody can get better results than me.
Old 01 January 2013   #3
yeah i expect nothing like real flow. just a stylized splashy thing for a
very small but closeup stereoscopic shot .

if i can get rid of jitter might be useable...guess ill try , more particles
Scott Turner
Old 01 January 2013   #4
If your splash is constant(ish) ( like a crown ) you could get by just using geo for the main form and some clever surface/curve emitting for the little droplets.

Hope you'll get there.

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Old 01 January 2013   #5
yeah its a crown type of thing...i was playing with blend shapes and all kinds of stuff lol...

i got something probably passible in form now but the meshing is still jittery , although
before it was much worse because i was using the soup smooth node and i think it may be the peak node causing the current jitteriness.

as well, the density of the mesh and particle resolution is crap but i need to stay interactive so i can actually the concept art is very simple and the low res particle sim actually seems way more similar than the hi res ones i was trying

..need to pull the bounce of ground plane and this is very test animation here lol
Scott Turner

Last edited by republicavfx : 01 January 2013 at 10:47 PM.
Old 01 January 2013   #6
Don't have time at the moment to make a video example but let me suggest to you this -

Use a Fluid to drive particles! You can use an extremely low res Auto resized fluid that sims realtime.

To get a better crown emission, scale a torus Fluid emitter up and play with the settings so you get a nice low res fluid blowing up and outward.

Emit TONS of particles and use the Fluid as a source, tweak Conserve to desired taste. Also turn on Liquid for better results. Depending on scale and settings you may have to fake things, like make the gravity on the particles 10x so when they leave the Fluids 'embrace' they will fall at the same speed or tweak the nucleus Space Scale.

I find this an incredibly fast and easy way to get more realistic splashes.

Used this for the close up rain splashes in Total Recall but alas, you know the compers.... Cant see shit in the end!

We usually just render Blobbies, but Im sure you can get something decent with the meshing.

From your animation, looks to me like you need to kill the particles when they hit the ground, not bounce to get rid of the jittering...

Good luck!


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Old 01 January 2013   #7
thanks for those ideas hadnt occured to me to advect under a lot of pressure to create a lot of shots very fast so im just cranking to try and get an animatic together. actually im emitting particles now from a torus geo...probably will try emitting fluids from same geometry and see what i get. thanks again
Scott Turner
Old 03 March 2013   #8
Sorry to do a bit of hijacking, but does anyone know how you can mesh multiple nParticle nodes together? (Using convert nParticles to polygons)

I realise it can't really be done due to the fact that the meshing controls are on the nParticle node itself, but how does one have say, condensation on a bottle (static) and some drops running down the sides (moving) react with each other as a mesh (not just to separate meshes intersecting each other)?

Does that make sense?
Old 03 March 2013   #9
Hi Roy

Here's one solution.

Look at the maya scene I attached.

There's three locators to mark your "hero" droplet position

There's one custom, per particle, vector attribute added into the nParticle posPP .

In pParticle's Creation Expression you get this:

if (nParticleShape1.particleId < 3) { 
	float $loc[] = getAttr( ("locator"+(nParticleShape1.particleId + 1) + ".t") );
	nParticleShape1.posPP = <<$loc[0],$loc[1],$loc[2]>>;	

and nParticle's Runtime Expression (both, Before and After Dynamics, if you will)

if (nParticleShape1.particleId < 3) nParticleShape1.position = nParticleShape1.posPP;

That's it

If you need more droplets, you could do it with goals and randomizing goalU and goalV.

Attached Files
File Type: zip (9.0 KB, 16 views)
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Old 03 March 2013   #10
That's awesome. Thanks for that. Still wish one could mesh multiple nParticle nodes though! Would be way easier
Old 03 March 2013   #11
The splash is coming along, Im not sure why you would use a fluid as a field in this case as most of your particles would only really be influenced by gravity and the field would just add more overheads to your sim time. Adding more particles should reduce mesh jitter and maybe increase the friction on your groundplane and particles so that they dont move away from each other which might cause the mesh to jump around a bit. Maybe add a secondary particle emission for spray with motion blur to give it more impact, tubes could work here.

Originally Posted by blade33ru: thanks for those ideas hadnt occured to me to advect under a lot of pressure to create a lot of shots very fast so im just cranking to try and get an animatic together. actually im emitting particles now from a torus geo...probably will try emitting fluids from same geometry and see what i get. thanks again
Old 03 March 2013   #12
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