Particle ports

let spark;

​

function setup() {

  createCanvas(windowWidth, windowHeight);

  spark = new Particle(random(width), random(height));

  background('black');

}

​

function draw() {

  spark.update();

  spark.show();

}

​

function Particle(x, y) {

  // The particle position has two components

  this.x = x;

  this.y = y;

  // The particle velocity (position change or "delta")

  this.dx = 0;

  this.dy = 0;

  // Acceleration is the change in velocity

  this.ax = 0;

  this.ay = 0;

​

  // Accelerate the particle by incrementing its acceleration

  this.applyForce = function(fx, fy){

    this.ax += fx;

    this.ay += fy;

  }

​

  // Update the particle position and accelearation

  this.update = function(){

    let b = 0.99; // viscosity

    this.x += this.dx;

    this.y += this.dy;

    this.dx += this.ax;

    this.dy += this.ay;

    this.dx *= b;

    this.dy *= b;

    this.ax = 0;

    this.ay = 0;

  }

​

  this.show = function(){

    fill('red');

    noStroke();

    circle(this.x, this.y, 5);

  }

}

​

function mousePressed() {

  let dx = mouseX - spark.x;

  let dy = mouseY - spark.y;

  let k = 100; // spring constant

  spark.applyForce(dx / k, dy / k);

}

​