How to get integers from an array of arrays?

Question

I have an array of arrays. It's a map for a game. The ones represent walls.

var walls = []
walls.push([0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0])
walls.push([0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0])
walls.push([0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0])
walls.push([0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0])
walls.push([0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0])
walls.push([1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0])
walls.push([0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0])
walls.push([0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0])
walls.push([0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0])
walls.push([0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0])
walls.push([0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0])
walls.push([0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0])
walls.push([0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0])
walls.push([0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0])
walls.push([0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0])
walls.push([0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0])
walls.push([0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0])
walls.push([0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0])
walls.push([0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0])
walls.push([0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0])

I want to detect if the player has hit one of the walls.

Then I need to get the x and y location as integers.

I want to do something like:

if (playerX == walls[i] && if playerY == walls[i][j]){
  playerDead();
}

I want to compare playerX to the row and playerY to the column. But the row is an array and the column is an integer. How do I turn the row into an integer?

/Jens

what exactly row should represent as a number? can you give an example? — Giorgi_Mdivani, Sep 23 '19 at 16:17

score 2 · Answer 1 · answered Sep 23 '19 at 16:20

2

You need to use your player location variables as indexes into the arrays:

if (walls[playerX][playerY] == 1){
  playerDead();
}

answered Sep 23 '19 at 16:20

Dark Falcon

43,592
5
83
98

1

I feel like there's a moderate chance that we're gonna want to reverse Y and X here, but that depends on OPs setup – TKoL Sep 23 '19 at 16:24
Thank you! Didn't thought of that! But I get an error. "TypeError: walls[playerX] is undefined." – Jens Sep 23 '19 at 17:05
@Jens, then your `playerX` value is out of range (< 0 or > your map size) or you need to swap `PlayerX` and `PlayerY`. – Dark Falcon Sep 23 '19 at 18:20
I solved it. The playerX was multiplied by 20, since the grid is 20x20 on a 400x400 canvas. It works now! – Jens Sep 23 '19 at 19:26

Antonio Pellegrini · Answer 2 · 2019-09-23T16:23:52.147

1

If playerX and playerY represent the x,y coordinates respectively then:

if(walls[playerX][playerY]){
    playerDead()
}

will run is player location corresponds to a wall.

edited Sep 23 '19 at 16:23

answered Sep 23 '19 at 16:17

Antonio Pellegrini

364
2
8

How to get integers from an array of arrays?

2 Answers2