Workshop › Scorched Earth-style Artillery › Step 18 of 23

Wind

What we are doing

Every shot has a new wind: a small push sideways, added to the speed each frame, like gravity but across. The top middle shows its direction and strength.

```js
let wind

const newWind = () => (wind = Math.round((Math.random() - 0.5) * 10) / 100) // -0.05 to 0.05

  newWind()

    newWind()

// One frame of flight: wind pushes sideways, gravity pulls down. Returns what it hit, or null.
  s.vx += wind

  ctx.textAlign = 'center'
  const arrow = wind > 0 ? '→' : wind < 0 ? '←' : ''
  ctx.fillText('Wind ' + arrow + ' ' + Math.abs(Math.round(wind * 100)), W / 2, 20)
```

What it means

• (Math.random() - 0.5) * 10 is between −5 and 5; rounded and divided by 100 it is −0.05 to 0.05, in steps of 0.01.
• A new wind comes with every new game and every turn.
• The display shows the wind ×100, so it reads as a whole number with an arrow.

Your turn

1. Above state, write wind; above fire, write newWind.
2. Call newWind() in reset before state, and in endTurn after the turn changes.
3. In fly, add the wind; update the comment above it.
4. In draw, show the wind before the turn text.

Skills: Velocity and gravity, Game states

← Win or lose The computer aims →

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