Snowflakes
Particle system simulating the motion of falling snowflakes. Uses an array of objects to hold the snowflake particles. Contributed by Aatish Bhatia.
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let snowflakes = []; // array to hold snowflake objects
function setup() {
createCanvas(400, 600);
fill(240);
noStroke();
}
function draw() {
background('brown');
let t = frameCount / 60; // update time
// create a random number of snowflakes each frame
for (let i = 0; i < random(5); i++) {
snowflakes.push(new snowflake()); // append snowflake object
}
// loop through snowflakes with a for..of loop
for (let flake of snowflakes) {
flake.update(t); // update snowflake position
flake.display(); // draw snowflake
}
}
// snowflake class
function snowflake() {
// initialize coordinates
this.posX = 0;
this.posY = random(-50, 0);
this.initialangle = random(0, 2 * PI);
this.size = random(2, 5);
// radius of snowflake spiral
// chosen so the snowflakes are uniformly spread out in area
this.radius = sqrt(random(pow(width / 2, 2)));
this.update = function(time) {
// x position follows a circle
let w = 0.6; // angular speed
let angle = w * time + this.initialangle;
this.posX = width / 2 + this.radius * sin(angle);
// different size snowflakes fall at slightly different y speeds
this.posY += pow(this.size, 0.5);
// delete snowflake if past end of screen
if (this.posY > height) {
let index = snowflakes.indexOf(this);
snowflakes.splice(index, 1);
}
};
this.display = function() {
ellipse(this.posX, this.posY, this.size);
};
}
