CODEWITHSUNDEEP
algorithmgraphicsgridformulabounds
itignition
itignition

Reputation: 31

Traversing a Grid of N Cells without declaring 2 variables (rows and columns)

I have been developing a game for canvas in JavaScript.

I have chosen to create the game without limitations to the world size grid. So if they wish to play with a grid size of N, the logic will generate it.

I have been working with bounds detection and have begun to program a function that will change the cell location on the grid if the user decides to travel outside the screen.

For simplicity sake, I have shrunk the grid size to N = 9 so you can visualize this. The grid looks like 

    [0][1][2]
    [3][4][5]
    [6][7][8]

If the user is to travels off a -x value Cell[0], they will appear at the rightmost x position of cell [2]. this is represented as SQRT(N). So I know that the rightmost corner is SQRT(N). I also know that N is the bottom right hand cell [8].

With that said, here is a sample of the cells and thier equation IDs.

   [0][1][SQRT(N)]
   [3][4][5]
   [N - SQRT(N)][7][N]

The grid above shows the x axis formulas for the 4 corners, but it is essential that I at least try to answer the inner cell equations before using static magic number switch-case conditionals.

here is some javscript code showing what I am explaining:

if (player.X < 0 - 10) {
    player.X = SCREEN_WIDTH;
    if (gameQuadrent == 0) {
        gameQuadrent = Math.floor(Math.sqrt(WORLD_SIZE));
    } else if (gameQuadrent == (WORLD_SIZE - Math.floor(Math.sqrt(WORLD_SIZE)))) {
        gameQuadrent = WORLD_SIZE;
    } else {
         gameQuadrent--;
    }
 }

Any more efficient ways of doing this? I am trying to solve this problem without having to move over to a fixed world size.

Much Appreciated.

Upvotes: 1

Views: 241

Answers (1)

tkleczek
tkleczek

Reputation: 338

Quadrent is on the left boundary of the world if it's number is a multiple of SQRT(WORLD_SIZE). Therefore the following code should update the gameQuadrent accordingly.

int side = Math.floor(Math.sqrt(WORLD_SIZE));
if (gameQuadrent % side) == 0) {
    gameQuadrent += side - 1;
}
else {
    --gameQuadrant;
}

Upvotes: 2

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