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Merge pull request #554 from lightest/particle_system
Particle system prototype. #gamification
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commit
43bffc51bc
331
src/visual/ParticleEmitter.js
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331
src/visual/ParticleEmitter.js
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/**
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* Grating Stimulus.
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*
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* @author Nikita Agafonov
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* @version 2022.3.0
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* @copyright (c) 2020-2023 Open Science Tools Ltd. (https://opensciencetools.org)
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* @license Distributed under the terms of the MIT License
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*/
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import * as PIXI from "pixi.js-legacy";
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const DEFAULT_POOL_SIZE = 1024;
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const DEFAULT_PARTICLE_WIDTH = 10;
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const DEFAULT_PARTICLE_HEIGHT = 10;
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const DEFAULT_PARTICLE_LIFETIME = 3; // Seconds.
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const DEFAULT_PARTICLE_COLOR = 0xffffff;
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const DEFAULT_PARTICLES_PER_SEC = 60;
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const DEFAULT_PARTICLE_V = 100;
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class Particle
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{
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constructor (cfg)
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{
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this.x = 0;
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this.y = 0;
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this.ax = 0;
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this.ay = 0;
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this.vx = 0;
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this.vy = 0;
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this.lifeTime = 0;
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this.widthChange = 0;
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this.heightChange = 0;
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this.sprite = undefined;
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this.inUse = false;
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if (cfg.particleImage !== undefined)
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{
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this.sprite = PIXI.Sprite.from(PIXI.Texture.from(cfg.particleImage));
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}
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else
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{
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this.sprite = new PIXI.Sprite(PIXI.Texture.WHITE);
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this.sprite.tint = cfg.particleColor || DEFAULT_PARTICLE_COLOR;
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}
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// TODO: Should we instead incorporate that in position calculation?
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// Consider: accurate spawn position of the particle confined by spawnArea.
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this.sprite.anchor.set(0.5);
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this.width = cfg.particleWidth || DEFAULT_PARTICLE_WIDTH;
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this.height = cfg.particleHeight || DEFAULT_PARTICLE_HEIGHT;
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}
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set width (w)
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{
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this._width = w;
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this.sprite.width = w;
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}
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get width ()
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{
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return this._width;
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}
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set height (h)
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{
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this._height = h;
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this.sprite.height = h;
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}
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get height ()
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{
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return this._height;
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}
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update (dt)
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{
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const dt2 = dt * dt;
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// Update velocity with current acceleration.
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this.vx += this.ax * dt;
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this.vy += this.ay * dt;
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// Update position with current velocity and acceleration.
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this.x = this.x + this.vx * dt + this.ax * dt2 * .5;
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this.y = this.y + this.vy * dt + this.ay * dt2 * .5;
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this.sprite.rotation = Math.atan2(this.vy, this.vx);
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this.sprite.x = this.x;
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this.sprite.y = this.y;
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if (this.width > 0)
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{
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this.width = Math.max(0, this.width + this.widthChange);
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}
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if (this.height > 0)
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{
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this.height = Math.max(0, this.height + this.heightChange);
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}
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this.lifeTime -= dt;
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if (this.width <= 0 && this.height <= 0)
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{
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this.lifeTime = 0;
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}
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if (this.lifeTime <= 0)
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{
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this.inUse = false;
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}
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}
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}
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export class ParticleEmitter
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{
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constructor (cfg = {})
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{
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this.x = 0;
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this.y = 0;
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this._cfg = cfg;
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this._particlesPerSec = cfg.particlesPerSec || DEFAULT_PARTICLES_PER_SEC;
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this._spawnCoolDown = 0;
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this._parentObj = undefined;
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this._particlePool = new Array(DEFAULT_POOL_SIZE);
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this.setParentObject(cfg.parentObject);
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this._fillParticlePool(cfg);
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}
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_fillParticlePool (cfg)
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{
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let i;
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for (i = 0; i < this._particlePool.length; i++)
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{
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this._particlePool[i] = new Particle(cfg);
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}
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}
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_setupParticle (p)
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{
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let spawnAreaWidth = this._cfg.spawnAreaWidth || 0;
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let spawnAreaHeight = this._cfg.spawnAreaHeight || 0;
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if (this._parentObj !== undefined && this._cfg.useParentSizeAsSpawnArea)
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{
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spawnAreaWidth = this._parentObj.width;
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spawnAreaHeight = this._parentObj.height;
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}
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const spawnOffsetX = Math.random() * spawnAreaWidth - spawnAreaWidth * .5;
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const spawnOffsetY = Math.random() * spawnAreaHeight - spawnAreaHeight * .5;
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const x = this.x + spawnOffsetX;
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const y = this.y + spawnOffsetY;
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p.x = x;
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p.y = y;
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p.ax = 0;
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p.ay = 0;
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if (Number.isFinite(this._cfg.initialVx))
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{
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p.vx = this._cfg.initialVx;
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}
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else if (this._cfg.initialVx instanceof Array && this._cfg.initialVx.length >= 2)
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{
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p.vx = Math.random() * (this._cfg.initialVx[1] - this._cfg.initialVx[0]) + this._cfg.initialVx[0];
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}
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else
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{
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p.vx = Math.random() * DEFAULT_PARTICLE_V - DEFAULT_PARTICLE_V * .5;
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}
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if (Number.isFinite(this._cfg.initialVy))
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{
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p.vy = this._cfg.initialVy;
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}
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else if (this._cfg.initialVy instanceof Array && this._cfg.initialVy.length >= 2)
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{
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p.vy = Math.random() * (this._cfg.initialVy[1] - this._cfg.initialVy[0]) + this._cfg.initialVy[0];
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}
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else
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{
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p.vy = Math.random() * DEFAULT_PARTICLE_V - DEFAULT_PARTICLE_V * .5;
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}
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p.lifeTime = this._cfg.lifeTime || DEFAULT_PARTICLE_LIFETIME;
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p.width = this._cfg.particleWidth || DEFAULT_PARTICLE_WIDTH;
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p.height = this._cfg.particleHeight || DEFAULT_PARTICLE_HEIGHT;
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p.widthChange = this._cfg.particleWidthChange || 0;
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p.heightChange = this._cfg.particleHeightChange || 0;
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// TODO: run proper checks here.
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if (this._cfg.particleImage)
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{
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p.sprite.texture = PIXI.Texture.from(this._cfg.particleImage);
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}
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else
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{
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p.sprite.texture = PIXI.Texture.WHITE;
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}
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if (this._cfg.particleColor !== undefined)
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{
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p.sprite.tint = this._cfg.particleColor;
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}
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else
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{
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p.sprite.tint = 0xffffff;
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}
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}
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_spawnParticles (n = 0)
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{
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let i;
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for (i = 0; i < this._particlePool.length && n > 0; i++)
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{
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if (this._particlePool[i].inUse === false)
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{
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this._particlePool[i].inUse = true;
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n--;
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this._setupParticle(this._particlePool[i]);
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this._cfg.container.addChild(this._particlePool[i].sprite);
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}
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}
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}
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_getResultingExternalForce ()
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{
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let externalForce = [0, 0];
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if (this._cfg.externalForces instanceof Array)
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{
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let i;
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for (i = 0; i < this._cfg.externalForces.length; i++)
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{
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externalForce[0] += this._cfg.externalForces[i][0];
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externalForce[1] += this._cfg.externalForces[i][1];
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}
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}
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return externalForce;
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}
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setParentObject (po)
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{
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this._parentObj = po;
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}
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/**
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* @desc: Adds external force which acts on a particle
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* @param: f - Array with two elements, first is x component, second is y component.
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* It's a vector of length L which sets the direction and the margnitude of the force.
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* */
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addExternalForce (f)
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{
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this._cfg.externalForces.push(f);
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}
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removeExternalForce (f)
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{
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const i = this._cfg.externalForces.indexOf(f);
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if (i !== -1)
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{
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this._cfg.externalForces.splice(i, 1);
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}
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}
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removeExternalForceByIdx (idx)
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{
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if (this._cfg.externalForces[idx] !== undefined)
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{
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this._cfg.externalForces.splice(idx, 1);
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}
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}
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update (dt)
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{
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let externalForce;
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// Sync with parent object if it exists.
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if (this._parentObj !== undefined)
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{
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this.x = this._parentObj.x;
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this.y = this._parentObj.y;
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}
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if (Number.isFinite(this._cfg.positionOffsetX))
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{
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this.x += this._cfg.positionOffsetX;
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}
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if (Number.isFinite(this._cfg.positionOffsetY))
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{
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this.y += this._cfg.positionOffsetY;
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}
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if (this._spawnCoolDown <= 0)
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{
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this._spawnCoolDown = 1 / this._particlesPerSec;
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// Assuming that we have at least 60FPS.
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const frameTime = Math.min(dt, 1 / 60);
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const particlesPerFrame = Math.ceil(frameTime / this._spawnCoolDown);
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this._spawnParticles(particlesPerFrame);
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}
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else
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{
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this._spawnCoolDown -= dt;
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}
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let i;
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for (i = 0; i < this._particlePool.length; i++)
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{
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if (this._particlePool[i].inUse)
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{
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externalForce = this._getResultingExternalForce();
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this._particlePool[i].ax = externalForce[0];
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this._particlePool[i].ay = externalForce[1];
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this._particlePool[i].update(dt);
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}
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// Check if particle should be removed.
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if (this._particlePool[i].lifeTime <= 0 && this._particlePool[i].sprite.parent)
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{
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this._cfg.container.removeChild(this._particlePool[i].sprite);
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}
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}
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}
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}
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@ -13,4 +13,5 @@ export * from "./TextStim.js";
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export * from "./VisualStim.js";
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export * from "./FaceDetector.js";
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export * from "./Survey.js";
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export * from "./ParticleEmitter.js";
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export * from "./Progress.js";
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