Workshop › Puzzle Bobble-style Bubble Shooter › Step 12 of 31

Bounce off the walls

What we are doing

Past the left or right wall, the bubble bounces: vx flips and the bubble is put back inside. Bank shots off the walls are a big part of the game.

```js
if (shot.x < R || shot.x > canvas.width - R) {
  shot.vx = -shot.vx // bounce off the side walls
  shot.x = Math.max(R, Math.min(canvas.width - R, shot.x))
}
```

What it means

• The bubble touches a wall when its centre is closer than R to it.
• -shot.vx reverses the sideways speed; the position is clamped back between R and canvas.width - R.

Your turn

In update, under shot.y += shot.vy, write the if block.

Skills: Velocity and gravity, Collision detection

← Fly Touching something? →

All steps

1. The night sky
2. One bubble
3. A grid of cells
4. Draw the grid
5. Bubbles that nest
6. The shooter
7. Aim upwards
8. Turn with the arrows
9. Aim with the pointer
10. Fire!
11. Fly
12. Bounce off the walls
13. Touching something?
14. Stick into the grid
15. Smaller steps
16. Six neighbours
17. Flood fill
18. Three in a row pop
19. Bubbles that fall
20. Cut them loose
21. Show the score
22. Only useful colors
23. Count the shots
24. The ceiling comes down
25. Win or lose
26. The danger line
27. The end message
28. Play again
29. Best score
30. A dotted guide
31. Build it yourself: swap bubbles