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Converting Coordinates To Block Position In Array

So I have an isometric map (but it could just as well be a 2D map) and an int[] array to store all of the block IDs on that map.

The array looks something like this (for a 4 by 4 block map):

0 0 1 0 0 2 0 1 0 2 1 0 1 0 3 2

That would translate into this on the map (first square):

0 0 1 0    0 0 1 0
0 2 0 1    0 2 X 1
0 2 1 0    0 2 1 0
1 0 3 2    1 0 3 2

There is an X on the second square.

How could I calculate X's position in the array? I tried doing basic multiplication: index = fieldWidth + fieldHeight but I can't get it to work.

Also, how could I calculate X's coordinates using it's position in the array?

This is probably useful to anyone making 2D/isometric games.

Solution

  • When Position is zero-based (= starts with 0):

    index = horizontalPos + verticalPos * 4

    If it starts with 1 use:

    index = horizontalPos - 1 + (verticalPos - 1) * 4

    Get the zero-based Positions of X with index i in the linear array:

    verticalPos = parseInt(i / 4); horizontalPos = i % 4;

    EDIT:

    To make it universally usable replace 4 with number of columns of your map.