Workshop › Pinball › Step 24 of 42

Two flippers

What we are doing

A flipper is a bar that turns around a fixed pivot. Each has a pivot (x, y), a resting angle and an up angle. In the game each flipper also has its current angle and turning speed.

```js
const FLIPPER_LENGTH = 62
const FLIPPERS = [
  { x: 130, y: 530, rest: 0.45, up: -0.45, key: 'left' },
  { x: 270, y: 530, rest: Math.PI - 0.45, up: Math.PI + 0.45, key: 'right' },
]

let flippers // { ...FLIPPERS[i], angle, speed }

  flippers = FLIPPERS.map((f) => ({ ...f, angle: f.rest, speed: 0 }))
```

What it means

• Angles are in radians and measured from "pointing right"; because y grows downwards, a positive angle tilts down. The left flipper rests at 0.45 (right and down) and goes up to -0.45.
• The right flipper points left, so its angles are around Math.PI (half a turn).
• { ...f, angle: f.rest, speed: 0 } copies all of f's fields into a new object and adds two more, so FLIPPERS itself never changes. The parentheses around { } make the arrow function return the object.

Your turn

1. Under the BUMPERS list write FLIPPER_LENGTH and FLIPPERS.
2. Under let ball write let flippers.
3. Make the flippers = ... line the first line of reset.

Skills: Game states, Arrays and objects

← Lit for a moment, points once Where is the tip? →

All steps

1. Paint the table
2. Draw one wall
3. A list of walls
4. The game loop
5. A ball in the lane
6. Draw the ball
7. Move by the velocity
8. Launch with Space
9. Gravity
10. Does the ball touch a wall?
11. Push the ball out
12. Bounce off the wall
13. Small steps and a speed limit
14. Ready or playing
15. The next ball
16. Three bumpers
17. The ball meets a bumper
18. A bumper kicks
19. A score and a fresh start
20. Points for every hit
21. Remember which bumper was hit
22. Light it up
23. Lit for a moment, points once
24. Two flippers
25. Where is the tip?
26. Flippers stop the ball
27. Which keys are held?
28. Which way to turn
29. Flip!
30. A moving wall
31. The flipper throws
32. Three balls
33. Balls left and game over
34. Play again
35. Remember the best score
36. Launch on letting go
37. Pull the spring
38. Show the spring
39. Two thumbs
40. Pull with a finger
41. Tap to play again
42. Build it yourself: slingshots