Workshop › Angry Birds-style Slingshot › Step 15 of 47

An empty sling in flight

What we are doing

While the bird flies, the sling should be empty: the pulled-back bird and the band are drawn only while aiming.

```js
if (state === 'aiming') {
  const bx = SLING.x - Math.cos(aim.angle) * aim.pull * 0.5
  ...
  ctx.arc(bx, by, BIRD, 0, Math.PI * 2)
  ctx.fill()
}
```

What it means

• Everything between { and } runs only when the state is 'aiming'.
• The lines inside move two spaces to the right, so the block is easy to see.

Your turn

Wrap the lines from const bx = ... down to the bird's ctx.fill() in if (state === 'aiming') { ... }.

Skills: Game states

← Aiming or flying Gone off the screen →

All steps

1. The sling
2. Sky and ground
3. Draw it again and again
4. The aim: an angle and a pull
5. A bird in the sling
6. Pull the bird back
7. The rubber band
8. Aim with the arrow keys
9. Bodies
10. Launch!
11. Move by the velocity
12. Gravity
13. Land on the ground
14. Aiming or flying
15. An empty sling in flight
16. Gone off the screen
17. Wait for calm
18. The next bird
19. See the path before you shoot
20. From a point to an aim
21. Grab the sling
22. Drag and let go
23. Wood and stone
24. A level as data
25. Push overlapping boxes apart
26. Bounce by mass
27. Every pair meets
28. Friction
29. Smaller steps
30. Hit points
31. Hard hits hurt
32. Things break
33. Pigs
34. Score
35. Show the score
36. Cracks
37. Three birds
38. Count the birds
39. Won or lost
40. The end panel
41. Play again
42. Three levels of data
43. Start any level
44. On to the next level
45. The best score
46. The right words
47. Build it yourself: the yellow bird