let p = null;

const b = 0.1;

const s = 0.03; 

const offset = new p5.Vector(0, 0, -0.5);

const vb = b + s / 2;

​

// utils

const mult = (vector, multiplier) => p5.Vector.mult(vector, multiplier);

const dot = (v1, v2) => p5.Vector.dot(v1, v2);

const sub = (v1, v2) => p5.Vector.sub(v1, v2);

​

// Cube setup

let offsets = null;

​

function preload() {

  createARCanvas();

}

​

function setup() {

  dir = p5.Vector.random3D().normalize().mult(0.0001);

  p = createVector(0, 0, 0);

  noFill();

​

  offsets = [

    [1, 0, 0, PI / 2, 0, 1, 0, 0],

    [-1, 0, 0, PI / 2, 0, 1, 0, 0],

    [0, 1, 0, PI / 2, 1, 0, 0, 0],

    [0, -1, 0, PI / 2, 1, 0, 0, 0],

    [0, 0, 1, 0, 0, 1, 0, 0],

    [0, 0, -1, 0, 0, 1, 0, 0],

  ];

​

  offsets = offsets.map((off) => [

    off[0] * vb,

    off[1] * vb,

    off[2] * vb,

    ...off.splice(3),

  ]);

}

​

function draw() {

  stroke(255);

​

  checkBounds();

​

  push();

  translate(offset);

​

  drawBounds();

​

  push();

  p.add(dir);

  translate(p);

  box(s, s, s);

  pop();

​

  pop();

}

​

function drawBounds() {

  for (let i = 0; i < 6; i++) {

    const [x, y, z, angle, ex, ey, ez, f] = offsets[i];

    if (f > 0) {

      fill(255, 255, 255);

    }

​

    push();

    translate(x, y, z);

    rotate(angle, createVector(ex, ey, ez));

    scale(vb * 2);

    rect(-0.5, -0.5, 1, 1);

    pop();

​

    noFill();

    if (f == 1) {

      bip();

      offsets[i][7] = 2; // hack make it happen only once

      setTimeout(() => {

        offsets[i][7] = 0;

      }, 50);

    }

  }

}

​

function checkBounds() {

  let normal = null;

  if (p.x > b) {

    normal = createVector(-1, 0, 0);

    offsets[0][7] = 1;

  }

​

  if (p.x < -b) {

    normal = createVector(1, 0, 0);

    offsets[1][7] = 1;

  }

​

  if (p.y > b) {

    normal = createVector(0, 1, 0);

    offsets[2][7] = 1;

  }

​

  if (p.y < -b) {

    normal = createVector(0, -1, 0);

    offsets[3][7] = 1;

  }

​

  if (p.z > b) {

    normal = createVector(0, 0, -1);

    offsets[4][7] = 1;

  }

​

  if (p.z < -b) {

    normal = createVector(0, 0, 1);

    offsets[5][7] = 1;

  }

​

  if (normal === null) return;

​

  // reflection v′= v−2(v⋅n)n

  // could just use p5 reflect method

  let d = dot(normal, dir);

  let proj = mult(normal, d);

​

  dir = sub(dir, mult(proj, 2));

}

​

function bip() {

  let osc = new p5.Oscillator("sine");

  osc.freq(440); // Frequency in Hz (A4 note)

  osc.start();

  osc.amp(0.5, 0.1); // Set amplitude to 0.5 over 0.1 seconds

  osc.stop(0.2); // Stop after 0.2 seconds

}

​