Workshop › Wolfenstein-style 3D Maze › Step 6 of 18

Is it a wall?

What we are doing

To stop at walls we need two questions. tileAt tells which tile a point is on. blocked tells whether the player, standing at a point, would be inside a wall. The player is not a point but a small square, 0.2 tiles each way from the middle, so we check its four corners.

```js
const RADIUS = 0.2 // how close the player can get to a wall

function tileAt(x, y) {
  return MAP[Math.floor(y)][Math.floor(x)]
}

// Is any corner of the player's little square inside a wall?
function blocked(x, y) {
  for (const [cx, cy] of [[-RADIUS, -RADIUS], [RADIUS, -RADIUS], [-RADIUS, RADIUS], [RADIUS, RADIUS]]) {
    if (tileAt(x + cx, y + cy) !== '.') return true
  }
  return false
}
```

What it means

Math.floor turns a position like 2.7 into the tile number 2. The row comes from y, the column from x.
The loop visits the four corner offsets; [cx, cy] unpacks each pair.
If any corner is on something other than floor, the spot is blocked.

Your turn

Above MINI, write RADIUS.
Above move, write tileAt and blocked.

Skills: Collision detection, Functions

← Walk Stop at walls, slide along them →

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