Particle system properties' unit


I fail to understand which unit the properties of the particle system are expressed in.
For example lifeTime: it doesn’t seems to be expressed in seconds, neither in millisecond.

Also everything seems to depend on updateSpeed, but again, I fail to see in which unit it is expressed, and even slow update speed still produce fluid particle movements.

Even emitRate which is said to be expressed in “particle per second” experience slowdown/speedup when lowering/raising the updateSpeed.

Ok it seems that the life time in seconds is : lifeTime / ( 100 * updateSpeed ).

But I’m still unsure what is updateSpeed (number of cycle per ms?).

Obviously the update speed is the time before each call for a particle frame update. It can be tuned independently because particles can heavily impact performance. So you can adjust the update speed of your particles to your best ratio of performance vs quality/smoothness for a particlesystem effect. You can do it separately for each PS.

Raising updateSpeed make things faster, so it is not the time (period, or delay) between update. It’s more a kind of frequency, but in which unit?

Yes, it’s in the text updateSPEED. If you increase speed you will increase the number of times the particles frame is updated (and therefor your animation goes faster). And I’m not sure, but I believe it must be ms. However note that it will also depend on your framerate (as far as I could see from my tests).

For GPUParticleSystem the lifetime would be in seconds, but for the (CPU) ParticleSystem it seems more complicated…

You can have a look here:


1 Like