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multiple_gravitational_attractors.html
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multiple_gravitational_attractors.html
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<!DOCTYPE html>
<html>
<head>
<script language="javascript" type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/p5.js/1.1.9/p5.js"></script>
</head>
<body>
<script>
let balls = [];
let numBalls = 10;
let attractors = [];
let vel = 3;
function setup() {
createCanvas(900, 600);
for (let i = 0; i < numBalls; i++) {
balls[i] = new Ball(random(width), random(height), 3, random(-vel, vel), random(-vel, vel));
}
for (let i = 0; i < 3; i++) {
attractors[i] = new Attractor(random(width - 150), random(height - 150), 100, 'plus');
}
}
function draw() {
background(0);
for (let [i, b] of balls.entries()) {
b.update();
b.edges();
b.paths();
b.show();
for (let i = 0; i < b.path.length; i++) {
if (b.path.length > 1000) {
b.path.splice(0, 1);
}
noFill();
strokeWeight(2);
stroke(b.color, 50);
point(b.path[i].x, b.path[i].y);
}
for (let [i, a] of attractors.entries()) {
a.show();
a.attract(b);
}
}
}
function mouseClicked() {
if (keyCode === UP_ARROW) {
attractors.push(new Attractor(mouseX, mouseY, 100, "plus"));
} else if (keyCode === DOWN_ARROW) {
attractors.push(new Attractor(mouseX, mouseY, 100, "minus"));
}else if (keyCode === LEFT_ARROW) {
balls.push(new Ball(mouseX, mouseY, 10, random(-5, 0), random(-5, 5)));
}else if (keyCode === RIGHT_ARROW) {
balls.push(new Ball(mouseX, mouseY, 10, random(0, 5), random(-5, 5)));
}
}
class Ball {
constructor(x, y, m, vx, vy) {
this.pos = createVector(x, y);
this.vel = createVector(vx, vy);
this.acc = createVector(0, 0);
this.mass = m;
this.r = sqrt(this.mass) * 2;
this.color = color(random(10, 215), random(10, 215), random(10, 215));
this.path = [];
}
applyForce(force) {
let f = p5.Vector.div(force, this.mass);
this.acc.add(f);
}
drawArrow(showColor, size, f) {
if (f.x != 0 || f.y != 0) {
push();
stroke(color(showColor));
fill(color(showColor));
translate(this.pos.x, this.pos.y);
line(0, 0, f.x * size, f.y * size);
rotate(f.heading());
translate(f.mag() * size, 0);
let arrowSize = 7;
triangle(0, arrowSize / 2, 0, -arrowSize / 2, arrowSize, 0);
pop();
}
}
update() {
this.vel.add(this.acc);
this.pos.add(this.vel);
this.acc.set(0, 0);
if (this.vel.x !== 0 || this.vel.y !== 0 && this.vel.y !== 1) {
this.drawArrow('#ffff33', 5, this.vel);
}
}
edges() {
if (this.pos.x <= this.r || this.pos.x >= width - this.r) {
this.vel.x = -this.vel.x
}
if (this.pos.y <= this.r || this.pos.y >= height - this.r) {
this.vel.y = -this.vel.y
}
if (this.pos.x > width - this.r) {
this.pos.x = width - this.r;
}
if (this.pos.x < this.r) {
this.pos.x = this.r;
}
if (this.pos.y > height - this.r) {
this.pos.y = height - this.r;
}
if (this.pos.y < this.r) {
this.pos.y = this.r;
}
}
paths() {
this.path.push({
x: this.pos.x,
y: this.pos.y
});
}
show() {
stroke(255);
strokeWeight(1);
fill(this.color, 80);
ellipse(this.pos.x, this.pos.y, this.r * 2);
}
}
class Attractor {
constructor(x, y, m, s) {
this.pos = createVector(x, y);
this.mass = m;
this.r = sqrt(this.mass) * 2;
this.sign = s;
this.color = color(255, 0, 100);
}
attract(ball) {
let force = p5.Vector.sub(this.pos, ball.pos);
let distanceSq = constrain(force.magSq(), 100, 100000);
let G = 5;
let strength = G * (this.mass * ball.mass) / distanceSq;
force.setMag(strength);
if (this.sign == "minus") {
force.mult(-1);
this.color = color(51, 204, 51);
}
ball.applyForce(force);
}
show() {
noStroke();
fill(this.color);
ellipse(this.pos.x, this.pos.y, this.r * 2);
}
}
</script>
</body>
</html>