Workshop › Scorched Earth-style Artillery › Step 15 of 23

The computer's shot

What we are doing

On its turn the computer "thinks" for one second (60 frames) and then fires with its barrel as it is. It doesn't aim yet; that comes later. A small triangle above a tank shows whose turn it is.

```js
let thinking // frames until the computer shoots

  if (turn === 1) thinking = 60

  if (state === 'aiming' && turn === 1 && --thinking === 0) {
    fire()
  }

  for (const [i, t] of tanks.entries()) {

    if (i === turn && state === 'aiming') {
      ctx.fillStyle = '#0f172a'
      ctx.beginPath()
      ctx.moveTo(t.x - 5, t.y - 34)
      ctx.lineTo(t.x + 5, t.y - 34)
      ctx.lineTo(t.x, t.y - 27)
      ctx.fill()
    }
```

What it means

• thinking counts down from 60 on the computer's turn; at 0 it fires.
• fire already uses tanks[turn], so the same function fires for the computer.
• tanks.entries() gives each tank with its number i, to compare with turn.
• The triangle is a filled path of three points, pointing down at the tank.

Your turn

1. Under state, write thinking; in endTurn, start thinking on the computer's turn.
2. In update, after the explosion block, fire when thinking is over.
3. In draw, number the tanks in the loop, and draw the triangle after the health bar.

Skills: Game states, The game loop

← Taking turns Hitting a tank →

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