Workshop › Scorched Earth-style Artillery › Step 14 of 23

Taking turns

What we are doing

After each shot the turn passes to the other tank. When it's the computer's turn, your keys don't aim and Space doesn't fire. The top right says whose turn it is. (The computer learns to shoot in the next step.)

```js
function endTurn() {
  turn = 1 - turn
  state = 'aiming'
}

    endTurn()

  if (state !== 'aiming' || turn !== 0) return

    if (turn === 0) fire()

  ctx.textAlign = 'right'
  ctx.fillText(turn === 0 ? 'Your turn' : 'Computer', W - 10, 20)
```

What it means

• 1 - turn flips 0 to 1 and 1 to 0.
• The explosion now ends with endTurn() instead of going back to aiming.
• aimBy and Space only work on your turn, while aiming.

Your turn

1. Above update, write endTurn; when the explosion ends, call it.
2. At the top of aimBy, aim only on your turn; on Space, fire only on your turn.
3. At the end of draw, show whose turn it is.

Skills: Game states

← Damage The computer's shot →

All steps

1. The ground
2. Hills
3. Two tanks
4. The barrel
5. The game loop
6. Aim
7. Angle and power
8. Fire!
9. Flight
10. Boom
11. Craters
12. Falling tanks
13. Damage
14. Taking turns
15. The computer's shot
16. Hitting a tank
17. Win or lose
18. Wind
19. The computer aims
20. Aim with the mouse
21. Drag and let go
22. The atan2 trap
23. Build it yourself: a trail