Workshop › Wolfenstein-style 3D Maze › Step 7 of 18

Stop at walls, slide along them

What we are doing

Now move asks before moving. Across and down are asked separately: walking diagonally into a wall stops only the part that would enter it, so the player slides along the wall instead of sticking to it.

```js
// Moving each axis on its own lets the player slide along a wall instead of sticking to it.
function move(dx, dy) {
  if (!blocked(player.x + dx, player.y)) player.x += dx
  if (!blocked(player.x, player.y + dy)) player.y += dy
}
```

What it means

• The first line moves across only if the new spot is free; the second moves down only if that spot is free.
• ! means "not": move when it is not blocked.

Your turn

Replace the body of move with the two checks, and write the comment above it.

Skills: Collision detection

← Is it a wall? A ray: where it starts →

All steps

1. The map
2. The player
3. Ceiling, floor and a loop
4. Turn around
5. Walk
6. Is it a wall?
7. Stop at walls, slide along them
8. A ray: where it starts
9. A ray: the grid lines
10. A ray: walk to the wall
11. The 3D view
12. No fish-eye
13. Light and shade
14. A timer
15. Escape!
16. Best time
17. Touch controls
18. Build it yourself: run