Workshop › Pac-Man-style Maze Chase › Step 24 of 42

Scatter or chase?

What we are doing

Ghosts that always chase would bunch up in a line. So they switch modes on a clock: in every 27-second cycle, the first 7 seconds are scatter (each ghost goes to its own corner, a breather for you), the rest is chase. One counter and % make a repeating schedule.

```js
const SCATTER = 420 // frames of scatter at the start of every 27-second cycle
const CYCLE = 1620

let clock // frames played on this life, for the scatter / chase cycle

  clock = 0

function mode() {
  return clock % CYCLE < SCATTER ? 'scatter' : 'chase'
}

function update() {
  clock += 1
```

What it means

clock counts frames since the actors were placed; placeActors sets it back to 0.
clock % CYCLE goes 0, 1, ... 1619 and starts again: the place in the current cycle. Below SCATTER (7 seconds) it is scatter time.

Your turn

Under GHOSTS write SCATTER and CYCLE; under let level write let clock.
In placeActors, at the end, write clock = 0.
Above target, write mode.
At the top of update, write clock += 1 and an empty line.

Skills: Game states

← One by one out of the house Every ghost to its corner →

All steps