Occasionally I have this birthing problem with particles:

I emit particles and all goes well until suddenly, at one single frame, a bunch of particles is emitted at totally random positions and then of course the whole thing is messed up. I've had this on several scenes now and it drives me nuts because I can't see why it should do that, and I can't figure out a way around it.

I wonder if anybody has come across this before, what the reason and cure for it is.

example scene ?

rob

Hm. I have one here but with geometry bgeos that are 5K a frame…soo… I7ll see if I can isolate the problem area.

generally to have exact control over where your particles are emitted from I tend to scatter points over the object and emit $NPT amount of particles (impulse birthrate).

Don't know if that helps in your case?

The problem you're experiencing is likely caused by the interplay between the birth rate and the birth probability on your source POP. The constant birth rate is the number of particles you want born every second. If your birth probability drops to 0 preventing particles from being born on a given frame, the particles demanded by the constant birth rate will still need to be birthed later. If your birth probability prevents births over many frames, the number of these pending births can build up.

Often you can work around this issue by controlling the birth rate appropriately.

Ondrej
Often you can work around this issue by controlling the birth rate appropriately.

Jeff Lait helped me with this a while back. I pass it on…

jlait
2009-10-20 10:03:31 (EDT): jlait:
You need to drive the constant birth rate by an expression that depends on the total emission you desire. This can be done by using an attribpromote to compute the total emission as a detail attribute and then an expression like
100 * detail(“/obj/grid_object1/TOTALEMIT”, “emit”, 0)

Attached is an example thereof.

Thanks so much for that. So the problem it does exist after all. (For a while I thought I was just rambling crazy stuff.)