Particlesystem resets when changing emission rate

dexter_deluxe · January 7, 2020, 3:18pm

Hi Community,

I want to change the emission rate of a particle system (time between particle births) during runtime, to increase the particle count.

Unfortunately, the particle system gets reset every time the emission rate is changed.

Sample: https://playcanvas.com/project/658366/overview/particle-emission-test

Is there a proper way of increasing the emission smoothly?

Any hints appreciated,
Rene

Leonidas · January 7, 2020, 3:42pm

Hi @dexter_deluxe, this indeed could be useful but I am not sure if it’s doable.

Emission rate is part of the complex properties on the particle system component that force a reset when they get updated:

github.com

playcanvas/engine/blob/26a2fa84e0ad96e80ffec31f202f6c34a91e2650/src/framework/components/particle-system/component.js#L17


    'emitterExtentsInner',
    'emitterRadiusInner',
    'loop',
    'initialVelocity',
    'animSpeed',
    'normalMap',
    'particleNormal'
];


// properties that need rebuilding the particle system
var COMPLEX_PROPERTIES = [
    'numParticles',
    'lifetime',
    'rate',
    'rate2',
    'startAngle',
    'startAngle2',
    'lighting',
    'halfLambert',
    'intensity',
    'wrap',

You could try and force the emitter to treat your rate update as a simple property, something like this:

this.entity.particlesystem.emitter.rate = this.entity.particlesystem.rate2 = targetRate;
this.entity.particlesystem.emitter.resetMaterial();

I haven’t tested this not sure how it will behave.

github.com

playcanvas/engine/blob/26a2fa84e0ad96e80ffec31f202f6c34a91e2650/src/framework/components/particle-system/component.js#L545


            if (this.emitter) this.emitter[name] = newValue;
        }
        if (this.emitter) {
            this.reset();
            this.emitter.resetMaterial();
            this.rebuild();
        }
    }
},


onSetSimpleProperty: function (name, oldValue, newValue) {
    if (this.emitter) {
        this.emitter[name] = newValue;
        this.emitter.resetMaterial();
    }
},


onSetComplexProperty: function (name, oldValue, newValue) {
    if (this.emitter) {
        this.emitter[name] = newValue;
        this.reset();

yaustar · June 16, 2022, 2:11pm

Created a ticket as this has come up again: Be able to change the particle emission rate without needing to regenerate the whole system · Issue #4336 · playcanvas/engine · GitHub