(10-05-2019, 10:16 AM)Komsur Wrote: Hi,

I'm experimenting with changing the Num Particles field during run time, this causes the Active Particles to be set to 0, and all emission stops and the Editor needs a restart.

Any ideas?

Thanks.

(10-05-2019, 11:05 AM)josemendez Wrote: You cannot change the size of the emitter's particle pool at runtime. This is because Obi is designed to preallocate memory when possible, to avoid CG spikes and memory allocation overhead.

Each actor (such as the ObiEmitter) allocates particles from the solver once, when it is initialized. Then it spawns particles from this pool by increasing the amount of ActiveParticles, when a particle dies it is returned to the pool by swapping it with the last active one and decreasing ActiveParticles.

So:
- NumParticles is the maximum amount of particles that can exist in the emitter, its pool size. This should not be changed at runtime, if you do then the emitter will be invalidated and all particles deactivated.

- ActiveParticles is the current amount of emitted particles, between 0 and NumParticles. This changes dynamically at runtime.

(13-05-2019, 08:02 AM)Komsur Wrote: Okay, so, is there a way of forcing the amount of active particles? I see that it's a read-only field, so probably not.

(13-05-2019, 08:29 AM)josemendez Wrote: Why'd you want to do that? this is entirely managed by the emitter, you should never need to modify the number of active particles directly. Moreover, the amount of particles used to represent a certain volume of fluid is automatically calculated from the resolution and emission speed. The pool size (num particles) is allowed to be set in order to cap the maximum amount of particles that can ever be active, but otherwise thinking in terms of particle count is discouraged. Unlike a regular particle system, the amount of fluid is expressed in volume units, not particle counts.

That being said, you can ensure a certain amount of particles is always active by setting the lifespan to inifinite, then using "Burst" emission mode so that all particles needed to cover the emission shape are emitted at once.

(13-05-2019, 02:02 PM)Komsur Wrote: Ideally, I'd like to change the amount of fluid that is spawned based on a flow rate float value we're receiving from another program, as that float value would be dynamically changing and I'd like to avoid making two emitters for the low and high float values.