Fade particles before they die

DavidPripas · December 2, 2020, 8:53am

How are you guys handling fading out particles before death in the latest Spark version?

There’s this patch [here] (https://www.facebook.com/groups/SparkARcommunity/permalink/936278956784147/) but it doesn’t seem to do anything besides attributing a lower opacity to all the particles. I know there was also a script for this (made by you, Josh?), but is there an updated v93+ version of it?

josh_beckwith · September 1, 2020, 7:12pm

Ah yes, my old script! Thanks to Lasse, here’s an updated one here:

github.com

Spark-AR-Community/SparkAR-Snippets/blob/master/EmitterParticleFade.js

//
// In this script we show how to fade out particles from
// a emitter. 
//
// Original post was created by Josh Beckwith
// URL: https://www.facebook.com/groups/SparkARcommunity/permalink/683989935346385/
//

//
// Include modules
//
const Scene = require('Scene');
const Animation = require('Animation');

// Load 'emitter0' object.
Scene.root.findFirst('emitter0').then(emitter => {
  // emitter0 loaded and ready to be used.
  
  // Animate per channel in a HSVA color model.
  // We specify a easing functions for the

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DavidPripas · September 1, 2020, 7:46pm

Used the script, double checked everything, tried different easings, it still looks like they’re just disappearing, not fading out completely

edit - set lifetime for particles 4 seconds (it was 9 before): https://www.instagram.com/ar/690325451555081/?ch=YmQ3NmFhYjE4YmNhM2Q1ZWZlNzI4YTg4NWJkZTViZjE%3D

josh_beckwith · September 1, 2020, 9:45pm

This stuff has never been intuitive to me. I still don’t fully understand it, but I think “hsvaColorModulationModifier” means that it is what changes in relative terms, and it’s not the absolute value. So… try setting your particle material alpha to zero initially? I always have to fiddle with things for a while before it works.