How do I represent a hextile/hex grid in memory?

Answer 1

Such a grid can be represented in a two-dimensional array:

If

   2
7     3
   1   
6     4
   5

is the number one with its neighbors in the hex grid, then you can put this into a 2D array like so:

2 3
7 1 4
  6 5

Obviously neighbor-ness is determined in this grid not only by being horizontally or vertically adjacent but also using one diagonal.

You can use a graph too, if you like to, though.

Answer 2

   2
7     3
   1   
6     4
   5

You can also try to 'flat' rows of your map. For this example it would be:

  2
7 1 3
6 5 4

Its sometimes more useful to have rows in one row:P

Answer 3

This article goes through how to set up a Isomeric/Hexagonal grid game. I recommend you have a look at the Forcing Isometric and Hexagonal Maps onto a Rectangular Grid section and the the movement section. Although it is different from what you are looking for it may help you formulate how to do what you want.

Answer 4

I would suggest something like the following (I'll use Delphi-style declarations):

type
  THexEdge = record
    Hexes: array[1..2] of Integer; // Index of adjoining hexes.
    // Other edge stuff goes here.
  end;

  THexVertex = record
    Hexes: array[1..3] of Integer; // Index of adjoining hexes.
    // Other vertex stuff goes here.
  end;

  THex = record
    Edges: array[1..6] of Integer; // Index of edge.
    Vertices: array[1..6] of Integer; // Index of vertex.
    // Other hex stuff goes here.
  end;

var
  Edges: array of THexEdge;
  Vertices: array of THexVertex;
  HexMap: array of THex;

Each hex has six edges and six vertices. Each edge keeps track of its two adjoining hexes, and each vertex keeps track of its three adjoining hexes (hexes on the edges of the map will be a special case).

There are many things that you could do a different way of course. You could use pointers rather than arrays, you could use objects rather than records, and you could store your hexes in a two-dimensional array as other answerers have suggested.

Hopefully, that might give you some ideas about one way to approach it though.