Workshop › Flappy-style Bird › Step 20 of 30

Through the opening

What we are doing

Collision, part two: is the bird fully inside the opening? Its top edge is below gapY and its bottom edge above gapY + GAP. The bird crashes when it is level with the pipe and not inside the opening.

```js
const overlapsX = bird.x + bird.r > pipe.x && bird.x - bird.r < pipe.x + PIPE_WIDTH
const insideGap = bird.y - bird.r > pipe.gapY && bird.y + bird.r < pipe.gapY + GAP
return overlapsX && !insideGap
```

What it means

• insideGap is true when the bird's box is fully between gapY and gapY + GAP.
• ! means "not": !insideGap is true when the bird is not inside the opening.

Your turn

In hitsPipe, add the insideGap line under overlapsX, and change the return line.

Skills: Collision detection

← Is the bird level with a pipe? Score each pipe once →

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