let sprites = []; //an array to store individual sprite frames

let direction = 1; // 0 up, 1 left, 2 right, 3 down - according to the rows indices of the sprite sheet

let step = 0; //the current step in the animation

let x; //the character's x position

let y;  //the character's y position

let speed = 3; //the animation speed

​

function preload() {

  spritesheet = loadImage("walking.png");

}

​

function setup() {

​

  createCanvas(500, 450);

​

  // 12 images across, 4 down, in the spritesheet

​

  let w = int(spritesheet.width / 12);

  let h = int(spritesheet.height / 4);

​

  for (let y = 0; y < 4; y++) {

    sprites[y] = [];

    for (let x = 0; x < 12; x++) {

      sprites[y][x] =

        spritesheet.get(x * w, y * h, w, h); //we are getting different parts or tiles of the entire sprite sheet image

    } // iterate over rows

  } // iterate over columns

​

  x = width / 2;

  y = height / 2;

​

  imageMode(CENTER);

​

    // Display first sprite in the center of canvas

  image(sprites[direction][step], x, y);

}

​

// nothing to do here because all the action

// happens in the keyPressed() callback

function draw() {}

​

function keyPressed() {

  // look at sprite sheet to determine 

  // which direction is which row

​

  if (keyCode === DOWN_ARROW) {

    direction = 0;

    y += speed;

  }

​

  if (keyCode === LEFT_ARROW) {

    direction = 1;

    x -= speed;

  }

​

  if (keyCode === RIGHT_ARROW) {

    direction = 2;

    x += speed;

  }

​

  if (keyCode === UP_ARROW) {

    direction = 3;

    y -= speed;

  }

​

    // Every so often 

    // advance to the next sprite

  if (frameCount % speed == 0) {

    step = (step + 1) % 12;

  }

​

    // Finally draw paint the sprite

  background(255);

  image(sprites[direction][step], x, y); //access the 2D array sprites by row with index 'direction' and column with index 'step'

}

​