Workshop › Pac-Man-style Maze Chase › Step 10 of 42

Move every frame

What we are doing

update runs once per frame and advances the player. The player's choose function, choosePlayer, stops it in front of a wall. The loop calls update before draw.

```js
function choosePlayer(p) {
  if (!canGo(p, p.dir)) p.dir = STOP
}

function update() {
  advance(player, choosePlayer)
}

function loop() {
  update()
  draw()
```

What it means

• choosePlayer is what advance calls at each tile center: if the way ahead is a wall, the player stops.
• update moves the player one frame; loop now updates, then draws.

Your turn

1. Under advance, leave an empty line and write choosePlayer.
2. Above function draw() { write update.
3. In loop, above draw(), write update().

Skills: The game loop

← One frame of movement Turns you can press early →

All steps

1. The maze as text
2. The game loop
3. Draw the walls
4. A set of pellets
5. Draw the pellets
6. The player
7. Where can you walk?
8. What a mover remembers
9. One frame of movement
10. Move every frame
11. Turns you can press early
12. Glide between tiles
13. Turn back at once
14. Swipes on a phone
15. Eat the pellets
16. Show the score
17. Clear the maze
18. A red ghost
19. A ghost never turns back
20. The ghost walks
21. The ghost hunts you
22. Four ghosts in the house
23. One by one out of the house
24. Scatter or chase?
25. Every ghost to its corner
26. Pink cuts you off
27. Orange is shy
28. Cyan works with red
29. Wait for the first key
30. Tell the player to start
31. Three lives
32. Caught!
33. Game over
34. Play again
35. Frighten the ghosts
36. Power pellets work
37. Scared ghosts wander slowly
38. Eat a scared ghost
39. Blue, then flashing
40. Harder levels
41. A best score that lasts
42. Build it yourself: the slow tunnel