proton-engine/src/behaviour/Force.js

Proton is a simple and powerful javascript particle animation engine.

import Vector2D from "../math/Vector2D";
import Behaviour from "./Behaviour";

export default class Force extends Behaviour {
  /**
   * @memberof! Proton#
   * @augments Proton.Behaviour
   * @constructor
   * @alias Proton.Force
   *
   * @param {Number} fx
   * @param {Number} fy
   * @param {Number} [life=Infinity] 			this behaviour's life
   * @param {String} [easing=ease.easeLinear] 	this behaviour's easing
   *
   * @property {String} name The Behaviour name
   */
  constructor(fx, fy, life, easing) {
    super(life, easing);

    this.force = this.normalizeForce(new Vector2D(fx, fy));
    this.name = "Force";
  }

  /**
   * Reset this behaviour's parameters
   *
   * @method reset
   * @memberof Proton#Proton.Force
   * @instance
   *
   * @param {Number} fx
   * @param {Number} fy
   * @param {Number} [life=Infinity] 			this behaviour's life
   * @param {String} [easing=ease.easeLinear] 	this behaviour's easing
   */
  reset(fx, fy, life, easing) {
    this.force = this.normalizeForce(new Vector2D(fx, fy));

    life && super.reset(life, easing);
  }

  /**
   * Apply this behaviour for all particles every time
   *
   * @method applyBehaviour
   * @memberof Proton#Proton.Force
   * @instance
   *
   * @param {Proton.Particle} particle
   * @param {Number} the integrate time 1/ms
   * @param {Int} the particle index
   */
  applyBehaviour(particle, time, index) {
    this.calculate(particle, time, index);
    particle.a.add(this.force);
  }
}