potree-sdk/src/objects/fireParticle/smoke/Particle.js

import * as THREE from "../../../../libs/three.js/build/three.module.js";
import Tween from '../Tween.js'
export default class Particle{
    constructor(prop={}){
        this.position     = new THREE.Vector3();
        this.velocity     = new THREE.Vector3(); // units per second
         
        this.angle             = 0;
        this.angleVelocity     = 0; // degrees per second
        this.angleAcceleration = 0; // degrees per second, per second
        this.size = 16.0;
    
        this.color   = new THREE.Color();
        this.opacity = 1.0;
                
        this.age   = 0;
        this.alive = 0; // use float instead of boolean for shader purposes	
        this.lastChangeVage = 0 //add


        this.sizeTween    = prop.sizeTween || new Tween( [0, 1], [32, 128] );
		this.opacityTween = prop.opacityTween || new Tween( [0.8, 2], [0.5, 0] );
		this.colorTween   = prop.colorTween || new Tween( [0.4, 1], [ new THREE.Vector3(0,0,0.2), new THREE.Vector3(0, 0, 0.5) ] );
   
   
   
   }

    update(dt)
    {
        this.position.add(this.velocity.clone().multiplyScalar(dt))
        this.velocity.multiplyScalar( 1+this.acceleration*dt )
        
        // convert from degrees to radians: 0.01745329251 = Math.PI/180
        this.angle         += this.angleVelocity     * 0.01745329251 * dt;
        this.angleVelocity += this.angleAcceleration * 0.01745329251 * dt;

        this.age += dt;
        
        // if the tween for a given attribute is nonempty,
        //  then use it to update the attribute's value

        if ( this.sizeTween.times.length > 0 )
            this.size = this.sizeTween.lerp( this.age/this.deathAge );
                    
        if ( this.colorTween.times.length > 0 )
        {
            var colorHSL = this.colorTween.lerp( this.age/this.deathAge );
            this.color = new THREE.Color().setHSL( colorHSL.x, colorHSL.y, colorHSL.z );
        }
        
        if ( this.opacityTween.times.length > 0 )
        {
            this.opacity = this.opacityTween.lerp( this.age/this.deathAge);
        }
    }
}