// Flappy Bird. Feel free to use these ideas in your

// own game. Adjust the work so that it is your own,

// and remove the explanatory comments if you do.

​

class Bird {

  constructor(x, diameter) {

    this.x = x

    this.y = 0

    this.diameter = diameter

    this.speed = 0

  }

  draw() {

    fill('yellow')

    circle(this.x, this.y, this.diameter)

    // The check makes sure the bird doesn't fall

    // through the ground. Incrementing the bird's

    // y position and its speed in the y-direction

    // is something we learned before.

    if (this.y < height) {

      this.y += this.speed

      this.speed += gravity

    }

  }

}

​

const gravity = 0.2

let bird

​

function setup() {

  createCanvas(400, 400)

  // Remember to create the bird after you call

  // createCanvas so you can use the p5.js width

  // and height variables, if needed

  bird = new Bird(width / 4, 30)

}

​

function draw() {

  background('cyan')

  bird.draw()

}

​

function keyPressed() {

  if (keyCode === 32) {

    // This is it folks: the physics of Flappy Bird

    // is just one line of code! When the space bar

    // is pressed, just set the speed to a negative

    // value! This will make it go up! The regular

    // gravity computation in draw() will slow the 

    // ascent and make it start going down eventually.

    bird.speed = -5

    // Okay there is a second line: make sure the bird

    // doesn't get stuck at the bottom of the canvas

    // so this kind of moves it up a bit when the

    // key is pressed so that it can ascend.

    bird.y = min(bird.y, height - 1)

  }

  // Remember to always add this for p5.js keyPressed:

  return false         

}

​