let size = 25;

let board = [];

let food; let head;

let dir;

let gameOver = false;

let length = 1;

​

function setup() {

  createCanvas(400, 400);

  frameRate(10);

  cols = width/size;

  rows = height/size;

  for (let i=0; i<cols; i++){

    board[i] = [];

    for (let j=0; j<rows; j++){

      board[i][j] = 0;

    }

  }

  food = createVector(int(random(0, cols)), int(random(0, rows)));

  head = createVector(int(random(0, cols)), int(random(0, rows)));

  dir = createVector(0, 0);

}

​

function draw() {

  background(220); 

  update();

  displayBoard();

  board[food.x][food.y] = -1;

  if (gameOver == false) {

    board[head.x][head.y] = length;

  } else {

    textAlign(CENTER, CENTER);

    textSize(50);

    text("GAME OVER", width/2, height/2);

  }

}

​

function update(){

  head.add(dir);

  if (dist(head.x, head.y, food.x, food.y) == 0) {

    generateFood();

    length += 1;

  }

  if (head.x < 0 || head.x > cols-1 || head.y < 0 || head.y > rows-1){

    gameOver = true;

    print("GAME OVER: HIT BORDER");

  } else if (board[head.x][head.y] > 1) {

    gameOver = true;

    print("GAME OVER: HIT ITSELF");

    dir.set(0, 0);

  } else {

    board[head.x][head.y] = 1 + length;

    removeTail();

  }

}

​

function generateFood(){

  while(true){

    food = createVector(int(random(0, cols)), int(random(0, rows)));

    if (board[food.x][food.y] == 0){

      break;

    }

  }

}

​

function removeTail(){

  for (let i=0; i<cols; i++){

    for (let j=0; j<rows; j++){

      if (board[i][j] > 0){

        board[i][j] -= 1;

      }

    }

  }

}

​

function displayBoard(){

  for (let i=0; i<cols; i++){

    for (let j=0; j<rows; j++){

      if (board[i][j] == 0) {

        fill(255);

      } else if (board[i][j] == -1){

        fill(255, 0, 0);

      } else {

        fill(255, 255, 0);

      }

      rect(i*size, j*size, size, size);

      // textAlign(CENTER, CENTER);

      // fill(0);

      // textSize(10);

      // text(board[i][j], size/2 + i*size, size/2 + j*size);

    }

  }

}

​

function keyPressed(){

  if (keyCode == LEFT_ARROW){

    dir = createVector(-1, 0);

  } else if (keyCode == RIGHT_ARROW) {

    dir = createVector(1, 0);

  } else if (keyCode == UP_ARROW) {

    dir = createVector(0, -1);

  } else if (keyCode == DOWN_ARROW) {

    dir = createVector(0, 1);

  }

}

​

​

​