// https://thecodingtrain.com/CodingChallenges/146-rendering-ray-casting.html

// https://youtu.be/vYgIKn7iDH8

​

// Rendering Ray Casting

​

let walls = [];

let ray;

let particle;

let xoff = 0;

let yoff = 10000;

​

const sceneW = 400;

const sceneH = 400;

let sliderFOV;

​

function setup() {

  createCanvas(800, 400);

  for (let i = 0; i < 4; i++) {

    let x1 = random(sceneW);

    let x2 = random(sceneW);

    let y1 = random(sceneH);

    let y2 = random(sceneH);

    walls[i] = new Boundary(x1, y1, x2, y2);

  }

  walls.push(new Boundary(0, 0, sceneW, 0));

  walls.push(new Boundary(sceneW, 0, sceneW, sceneH));

  walls.push(new Boundary(sceneW, sceneH, 0, sceneH));

  walls.push(new Boundary(0, sceneH, 0, 0));

  particle = new Particle();

  sliderFOV = createSlider(0, 360, 60);

  sliderFOV.input(changeFOV);

}

​

function changeFOV() {

  const fov = sliderFOV.value();

  particle.updateFOV(fov);

}

​

function draw() {

  if (keyIsDown(LEFT_ARROW)) {

    particle.rotate(-0.01);

  } else if (keyIsDown(RIGHT_ARROW)) {

    particle.rotate(0.01);

  } else if (keyIsDown(UP_ARROW)) {

    particle.move(1);

  } else if (keyIsDown(DOWN_ARROW)) {

    particle.move(-1);

  }

​

  background(0);

  for (let wall of walls) {

    wall.show();

  }

  particle.pos.x = mouseX

  particle.pos.y = mouseY

  particle.show();

​

  const scene = particle.look(walls);

  const w = sceneW / scene.length;

  push();

  translate(sceneW, 0);

  for (let i = 0; i < scene.length; i++) {

    noStroke();

    const sq = scene[i] * scene[i];

    const wSq = sceneW * sceneW;

    const b = map(sq, 0, wSq, 255, 0);

    const h = map(scene[i], 0, sceneW, sceneH, 0);

    fill(b);

    rectMode(CENTER);

    rect(i * w + w / 2, sceneH / 2, w + 1, h);

  }

  pop();

​

  // ray.show();

  // ray.lookAt(mouseX, mouseY);

​

  // let pt = ray.cast(wall);

  // if (pt) {

  //   fill(255);

  //   ellipse(pt.x, pt.y, 8, 8);

  // }

}

​