Workshop › Flappy-style Bird › Step 19 of 30

Is the bird level with a pipe?

What we are doing

Collision, part one. We treat the bird as the square box around its circle and ask: does it overlap the pipe horizontally? For now, being level with a pipe ends the game, even in the opening.

```js
function hitsPipe(pipe) {
  const overlapsX = bird.x + bird.r > pipe.x && bird.x - bird.r < pipe.x + PIPE_WIDTH
  return overlapsX
}

  if (hitGround || hitSky || pipes.some(hitsPipe)) state = 'over'
```

What it means

• The ranges overlap when the bird's right edge is past the pipe's left edge and the bird's left edge is before the pipe's right edge. && means "and".
• return overlapsX gives the answer back to the caller.
• pipes.some(hitsPipe) is true if any pipe is hit.

Your turn

1. Under addPipe, leave an empty line and write hitsPipe.
2. In update, add || pipes.some(hitsPipe) to the game-over condition.

Skills: Collision detection

← Remove the pipes you passed Through the opening →

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