Workshop › Flappy-style Bird › Step 11 of 30

The ground and the sky

What we are doing

When the bird's bottom edge reaches the ground, or its top edge the top of the screen, the game is over: the state becomes 'over', everything freezes, and flapping does nothing.

```js
function flap() {
  if (state === 'over') return
  state = 'playing'
  bird.vy = FLAP
}

  bird.y += bird.vy

  const hitGround = bird.y + bird.r >= canvas.height
  const hitSky = bird.y - bird.r <= 0
  if (hitGround || hitSky) state = 'over'
```

What it means

• >= means "greater than or equal", <= "less than or equal". Each comparison is true or false, and we give the answers names.
• hitGround || hitSky: either one ends the game.
• Once the state is 'over', update returns at once (frozen), and flap returns too.

Your turn

1. In flap, add if (state === 'over') return as the first line.
2. In update, under bird.y += bird.vy, leave an empty line and write the three new lines.

Skills: Collision detection, Game states

← Wait for the first flap Tell the player →

All steps

1. Get the canvas and the pen
2. Paint the sky
3. Draw the bird
4. A function that draws
5. A function that moves
6. The game loop
7. Gravity
8. A flap
9. Space, Up arrow or a tap
10. Wait for the first flap
11. The ground and the sky
12. Tell the player
13. A pipe as data
14. Draw the pipes
15. The world moves, not the bird
16. A new pipe at a random height
17. A pipe every 90 frames
18. Remove the pipes you passed
19. Is the bird level with a pipe?
20. Through the opening
21. Score each pipe once
22. Show the score
23. A function for a fresh start
24. Try again
25. One place where the game ends
26. Remember the best score
27. Show the best score
28. The same speed on every screen
29. No catching up after a pause
30. Build it yourself: a medal