Trying to get particle collisions to work

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  05 May 2003
Trying to get particle collisions to work


I am trying to use a collision object for the particles flowing out of the doorway. I want them to pour down the steps. But as you can see, many of them are "leaking" through the wall.

MPEG-4 Video (800KB)

The building you see is NOT the collision object, I made a simpler version of it for collisions. Then I made sure it had no polygons with more than 4 points (it was giving me error messages about that). The wall they are leaking through is thicker than the wall you see, yet they are stubbornly leaking.. Any suggestions?


P.S. Quicktime v6 will view the video clip, as well as RealOne.

"All war is deception." - Sun Tzu
  05 May 2003
I dont know what is going on, strange indeed.
The problem is obviously that not all particles detect the wall. I would split the flow of the particles. I would use 3 emitters, one coming out of the door and the second the liquid rising at the top of the stairs and one for the liquid running down the stairs. It could work if everything is set up properly. But I agree the scene would get alot complexer, but you get more control in return.
  05 May 2003
bevel the edges of you collision object. Or make the resolution smaller in your pfx options.
  05 May 2003
You are pressing FX Start right?
Try changing the resolution of PFX... (FX Browser)

Also try using Object Advanced, as the collision mode.

I had a similar problem too.....
Out of around 500 Particles, 40 of them collide with the object
and bounce off, the other 460 go straight-thru.

My resolution is set to 1mm
However my best guess, is i have particle size of
0.01 and a random of 0.08 (which must be too small for 1mm)

Making all my particles 1.0 seems to fix the problem.
So i need to use a smaller resolution than 1mm (ouch!)
Object Advanced seems to work better too..

Keep in mind that Particle size does not actually mean particle size.... It means the outer boundry used for collision detection,

Which is mind numbingly annoying......
Am i the only one living in this twilight zone?

If Hypervoxels is set to 15cm, and Particle size 0.01 and 0.08
Does this mean the collisions will be 0.01 % of 15cm?

And why does Hypervoxels Show Particles option, show very different particles to Particle FX's show particles option. ?

It could be that i have not slept in three days, so PFX is not making sense..... It could also be possible, that PFX is the damn reason i have not slept in three days....

And while i'm in a crabby mood.......
The Manual states: "Particle Size can be used by volumetric
plug-ins like Hypervoxels"

Would anybody like to let me know how one does this?

Because like most other areas of the Particle FX chapter in the manual, it does not tell you anything......

There is no explanation of the size effect options like:
Size>Density fixed(Mass Change)

What's scary is i use PFX frequently, and have never had so much trouble. Monday is lasting all week long this week.
  05 May 2003
are you sure all the collsion objects are within the same group?

It looks like the doorway is correct, but the front wall and side steps wall are in other groups, thus making them "invisible" to the particles.

Also make sure to hit fx_start. Sometimes it doesn't calculate right by scrubbing and/or not using fx_start.
~~ Ordinary people built the ark, specialists built the titanic.
  05 May 2003
The bevel tip helped TREMENDOUSLY.. Thank you!

It's not perfect yet, but it's 200% improved.

I haven't tried hitting the START button yet.. I'll try that too.

Thanks guys! I'll post an update when I get it all working right.


"All war is deception." - Sun Tzu
  05 May 2003
The animation is done now... Now I got piles of rendering ahead of me.. Here is a still image..

Thanks again for all your helpful suggestions!


"All war is deception." - Sun Tzu
  01 January 2006
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