SmokeParticles
a port of Dan Shiffman's SmokeParticleSystem example originally for Processing. Creates smokey particles :p
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// texture for the particle
let particle_texture = null;
// variable holding our particle system
let ps = null;
function preload() {
particle_texture = loadImage("assets/particle_texture.png");
}
function setup() {
//set the canvas size
createCanvas(640, 360);
//initialize our particle system
ps = new ParticleSystem(0, createVector(width / 2, height - 60), particle_texture);
}
function draw() {
background(0);
let dx = map(mouseX, 0, width, -0.2, 0.2);
let wind = createVector(dx, 0);
ps.applyForce(wind);
ps.run();
for (let i = 0; i < 2; i++) {
ps.addParticle();
}
// Draw an arrow representing the wind force
drawVector(wind, createVector(width / 2, 50, 0), 500);
}
/**
* This function draws an arrow showing the direction our "wind" is blowing.
*/
function drawVector(v, loc, scale){
push();
let arrowsize = 4;
translate(loc.x, loc.y);
stroke(255);
rotate(v.heading());
let len = v.mag() * scale;
line(0, 0, len,0);
line(len, 0, len-arrowsize, +arrowsize / 2);
line(len, 0, len-arrowsize, -arrowsize / 2);
pop();
}
//========= PARTICLE SYSTEM ===========
/**
* A basic particle system class
* @param num the number of particles
* @param v the origin of the particle system
* @param img_ a texture for each particle in the system
* @constructor
*/
let ParticleSystem = function(num, v, img_) {
this.particles = [];
this.origin = v.copy(); // we make sure to copy the vector value in case we accidentally mutate the original by accident
this.img = img_
for(let i = 0; i < num; ++i){
this.particles.push(new Particle(this.origin, this.img));
}
};
/**
* This function runs the entire particle system.
*/
ParticleSystem.prototype.run = function() {
// cache length of the array we're going to loop into a variable
// You may see <variable>.length in a for loop, from time to time but
// we cache it here because otherwise the length is re-calculated for each iteration of a loop
let len = this.particles.length;
//loop through and run particles
for (let i = len - 1; i >= 0; i--) {
let particle = this.particles[i];
particle.run();
// if the particle is dead, we remove it.
// javascript arrays don't have a "remove" function but "splice" works just as well.
// we feed it an index to start at, then how many numbers from that point to remove.
if (particle.isDead()) {
this.particles.splice(i, 1);
}
}
}
/**
* Method to add a force vector to all particles currently in the system
* @param dir a p5.Vector describing the direction of the force.
*/
ParticleSystem.prototype.applyForce = function(dir) {
let len = this.particles.length;
for(let i = 0; i < len; ++i){
this.particles[i].applyForce(dir);
}
}
/**
* Adds a new particle to the system at the origin of the system and with
* the originally set texture.
*/
ParticleSystem.prototype.addParticle = function() {
this.particles.push(new Particle(this.origin, this.img));
}
//========= PARTICLE ===========
/**
* A simple Particle class, renders the particle as an image
*/
let Particle = function (pos, img_) {
this.loc = pos.copy();
let vx = randomGaussian() * 0.3;
let vy = randomGaussian() * 0.3 - 1.0;
this.vel = createVector(vx, vy);
this.acc = createVector();
this.lifespan = 100.0;
this.texture = img_;
}
/**
* Simulataneously updates and displays a particle.
*/
Particle.prototype.run = function() {
this.update();
this.render();
}
/**
* A function to display a particle
*/
Particle.prototype.render = function() {
imageMode(CENTER);
tint(255, this.lifespan);
image(this.texture, this.loc.x, this.loc.y);
}
/**
* A method to apply a force vector to a particle.
*/
Particle.prototype.applyForce = function(f) {
this.acc.add(f);
}
/**
* This method checks to see if the particle has reached the end of it's lifespan,
* if it has, return true, otherwise return false.
*/
Particle.prototype.isDead = function () {
if (this.lifespan <= 0.0) {
return true;
} else {
return false;
}
}
/**
* This method updates the position of the particle.
*/
Particle.prototype.update = function() {
this.vel.add(this.acc);
this.loc.add(this.vel);
this.lifespan -= 2.5;
this.acc.mult(0);
}
