Destruction VFX - Collision slide, flickering particles - same old pro

[ChargingImage]

Hallo!

 

I've tried searching for solutions of this but probably I'm not asking the right questions.

 

here is the sim:

 

https://www.youtube.com/watch?v=i646JTxxEIY

 

1. Particles are sliding downwards along the walls (you can see it on the left wall clearly). I've tried increasing substeps, volume offset, vdb resolution, and some other stuff. Didn't work. Last resort is adding "vdb distance field" to push out particles just outside to fall down properly, but for that I need to dig up other tutorial I've watched, where this solution was made. And maybe there is simpler solution... (here YOU come in )

 

 

2. Other thing is flickering particles. This is another, pure collision problem.

 

https://youtu.be/MQJ6Ry3WJBM

(it's almost the same sim, just better vdb and more particles).

 

It appears where particles are trapped between 2 collision objects (particle fell on the ground, and moment later, block of rigid body goes to the same spot). How can I fix this? I've tried grouping <0.01 @vel_length and excluding them from gravity/collision/something but that didn't work that well. Maybe calculate acceleration and delete those with too high value - but still some innocent particles could be deleted in process.

 

Is there any kind of "switch off from sim" trigger in particles? I know there is @active in rigid bodies, but coudn't find something simmilar in here.

 

Ideas?

 

Overall, I'm not even sure should I bother because this problem is almost invisible... but still... I'm quite afraid that in rendering I'll see some jumping particles on the edges of geo, and I don't want manually delete them.

 

[Atom]

For Problem #2:

 

What you can do is drop down a couple of velocity nodes to control what happens after they hit a surface and bounce.

 

Create a group based upon the $JUSTHIT variable.

 

Then add a velocity node that decrease velocity based upon a multiplier for those particles that just hit something.

 

Create a new attribute called nonvelocity whose value is set based upon the $NUMHIT variable. This is your bounce count expression $NUMHIT==3 (choose bounce count).

 

Then lay down a second velocity node that examines the nonvelocity attribute and sets the velocity to zero after the number of bounces have occurred. Do this for $VX, VY, $VZ.

 

This kind of particle velocity refinement worked in the old particle system but might need some tweaking for the new one? But maybe this will give an idea of how to proceed.

Edited December 6, 2015 by Atom

[ChargingImage]

Thanks Atom! I'll give it a shot.