let resolution = 30;

let food;

let w, h;

let score = 0;

let specialFood = null;

let specialFoodChance = 0.1;

let specialFoodValue = 3;

​

const bgColor = 0;

const snakeColor = '#8FBC8F';

const foodColor = '#ADFF2F';

const specialFoodColor = '#FFD700';

​

function setup() {

  createCanvas(windowWidth, windowHeight);

  background(bgColor); 

  w = width / resolution;

  h = height / resolution;

  frameRate(10);

  snake = new Snake(snakeColor);

  addFood();

}

​

function draw() {

  background(bgColor);

​

  fill(foodColor);

  rect(food.x * resolution, food.y * resolution, resolution, resolution);

​

  if (specialFood) {

    fill(specialFoodColor);

    rect(specialFood.x * resolution, specialFood.y * resolution, resolution, resolution);

  }

  if (snake.eat(food)) {

    addFood();

    score++;

  }

  if (specialFood && snake.eat(specialFood, specialFoodValue)) {

    specialFood = null;

    score += specialFoodValue;

  }

  snake.update();

  snake.show();

​

  if (snake.endGame()) {

    print("GAME OVER!");

    background('#FF0000');

    noLoop();

  }

  //Score

  fill(255);

  textSize(20);

  text("Score: " + score, 10, 30);

}

​

function keyPressed() {

  if (keyCode === LEFT_ARROW && snake.dir.x !== 1)

    snake.setDir(-1, 0);

  else if (keyCode === RIGHT_ARROW && snake.dir.x !== -1)

    snake.setDir(1, 0);

  else if (keyCode === DOWN_ARROW && snake.dir.y !== -1)

    snake.setDir(0, 1);

  else if (keyCode === UP_ARROW && snake.dir.y !== 1)

    snake.setDir(0, -1);

}

​

function addFood() {

  let x = floor(random(w));

  let y = floor(random(h));

  food = createVector(x, y);

  if(!specialFood) {

    if (random(1) < specialFoodChance)

      specialFood = createVector(floor(random(w)), floor(random(h)));

    else specialFood = null;

  }

}

​

class Snake {

  constructor(snakeColor) {

    this.body = [];

    this.body[0] = createVector(floor(w / 2), floor(h / 2));

    this.dir = createVector(0, 0);

    this.len = 1;

    this.snakeColor = snakeColor;

  }

​

  update() {

    let head = this.body[this.body.length - 1].copy();

    this.body.shift();

    head.x += this.dir.x;

    head.y += this.dir.y;

​

    if (head.x >= w) {

      head.x = 0;

    } 

    else if (head.x < 0) {

      head.x = w - 1;

    }

    if (head.y >= h) {

      head.y = 0;

    } 

    else if (head.y < 0) {

      head.y = h - 1;

    }

​

    this.body.push(head);

  }

​

  show() {

    fill(this.snakeColor);

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

      rect(this.body[i].x * resolution, this.body[i].y * resolution, resolution, resolution);

    }

  }

​

  setDir(x, y) {

    this.dir.x = x;

    this.dir.y = y;

  }

​

  eat(pos, growAmount = 1) {

    let head = this.body[this.body.length - 1];

    let distance = dist(head.x, head.y, pos.x, pos.y);

    let collisionThreshold = 0.8;

​

    if (distance < collisionThreshold) {

      for (let i = 0; i < growAmount; i++) {

        this.body.unshift(createVector(this.body[0].x - this.dir.x, this.body[0].y - this.dir.y));

        this.len++;

      }

      return true;

    }

    return false;

  }

​

  endGame() {

    let x = this.body[this.body.length - 1].x;

    let y = this.body[this.body.length - 1].y;

​

    for (let i = 0; i < this.body.length - 1; i++) {

      let part = this.body[i];

      if (part.x === x && part.y === y) {

        return true;

      }

    }

    return false;

  }

}