Workshop › Flappy-style Bird › Step 15 of 30

The world moves, not the bird

What we are doing

The bird never really flies forward: the world slides backwards past it. Every frame of play, each pipe moves PIPE_SPEED pixels to the left.

```js
const PIPE_SPEED = 2

  for (const pipe of pipes) {
    pipe.x -= PIPE_SPEED
  }
```

What it means

• pipe.x -= PIPE_SPEED subtracts 2 from each pipe's x: it moves left.
• Changing pipe.x changes the object inside the array, so draw shows it in its new place.

Your turn

1. Under GAP, write const PIPE_SPEED = 2.
2. In update, under bird.y += bird.vy, leave an empty line and write the loop.

Skills: The game loop, Loops

← Draw the pipes A new pipe at a random height →

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