bouncing-ball.js

const kWindowSize = 400;
const kBallRadius = 50;

let x = 200;
let y = 200;

let vx = 3.5;
let vy = 1.8;


let c = lib220.newCanvas(kWindowSize, kWindowSize);

while(true) {
  lib220.sleep(16);
  x += vx;
  y += vy;
  if (x < kBallRadius) {
    x = kBallRadius + kBallRadius - x;
    vx = -vx;
  } else if (x > kWindowSize - kBallRadius) {
    x = kWindowSize - kBallRadius - (x - (kWindowSize - kBallRadius));
    vx = -vx;
  }
  if (y < kBallRadius) {
    y = kBallRadius + kBallRadius - y;
    vy = -vy;
  } else if (y > kWindowSize - kBallRadius) {
    y = kWindowSize - kBallRadius - (y - (kWindowSize - kBallRadius));
    vy = -vy;
  }
  c.clear();
  c.drawCircle(x, y, kBallRadius, [0, 0, 0]);
}