let v;

let a;

​

let r = 10;

​

let theta;

​

let Fthrust = 3;

let mass = 3;

​

function setup() {

  createCanvas(560, 400);

  p = createVector(width / 2, height / 2);

  v = createVector(0, 0);

  a = createVector(0, 0);

  theta = radians(90);

}

​

function draw() {

  background(255);

  if (keyIsDown(UP_ARROW)) {

    a.x = Fthrust * cos(theta) / mass;

  }

  v.add(a);

  p.add(v);

  a.mult(0);

  if (p.x > width + r) {

    p.x = 0;

  } else if (p.x < -r) {

    p.x = width;

  } else if (p.y > height + r) {

    p.y = 0;

  } else if (p.y < -r) {

    p.y = height;

  }

  stroke(0);

  strokeWeight(3);

  fill(200);

  translate(p.x, p.y);

  rotate(theta);

  beginShape();

  vertex(-r, r);

  vertex(0, -1.5 * r);

  vertex(r, r);

  endShape(CLOSE);

}