Generate isometric tile map with special tiletexture

Question

This is my first post here so please be gentle ;)

Im trying to make a tile map in XNA, and I got so far as generate my map randomly using a perlin method that generates a grayscaled texture that i use for tiledbased ground selection.

This is how i do it

     internal void RenderNew(int mapWidth, int mapHeight)
    {
        _mapHeigth = mapHeight;
        _mapWidth = mapWidth;

        Tiles = new Tile[_mapWidth, _mapHeigth];
        bool moveRowLeft = true;

        //Create the map array
        for (int y = 0; y < _mapHeigth; y++)
        {
            moveRowLeft = !moveRowLeft;
            for (int x = _mapWidth - 1; x >= 0; x--)
            {
                Tile t = new Tile(x, y, _mapWidth, _mapHeigth)
                    {
                        Position = new Vector2(x * tileWidth + (moveRowLeft ? tileWidth / 2 : 0), (y * tileHeight / 2))
                    };
                t.Ground = Tile.GroundType.Grass;
                Tiles[x, y] = t;
            }

        }
        //Generate the grayscaled perlinTexture
        GenerateNoiseMap(_mapWidth, _mapHeigth, ref perlinTexture, 20); 

        //Get the color for each pixel into an array from the perlintexture
        Color[,] colorsArray = TextureTo2DArray(perlinTexture);

        //Since a single pixel in the perlinTexture can be mapped to a tile in the map we can
        //loop all tiles and set the corresponding GroundType (ie texture) depending on the 
        //color(black/white) of the pixel in the perlinTexture.
        foreach (var tile in Tiles)
        {
            Color colorInPerlinTextureForaTile = colorsArray[tile.GridPosition.X, tile.GridPosition.Y];
             if (colorInPerlinTextureForaTile.R > 100)
            {
                tile.Ground = Tile.GroundType.Grass;
            }
            else if (colorInPerlinTextureForaTile.R > 75)
            {
                tile.Ground = Tile.GroundType.Sand;
            }
            else if (colorInPerlinTextureForaTile.R > 50)
            {
                tile.Ground = Tile.GroundType.Water;
            }
            else
            {
                tile.Ground = Tile.GroundType.DeepWater;
            }
        }
    }

The texture sheet that i use thus contains texture for the Sand,Grass,Water and Deepwater. But it also contains tiles for creating nice overlaps, ie going from sand to water etc.

!Tried to post my tileset image but i couldnt case I'm to new on this site ;(

So my question is, how can i use the overlapping tiles as well? How do i know when to use a overlapping tile and in what direction?

All tiles also "know" its neighbour tile in all eigth directions (S,SE,E,NE,N,NW,W,NE)

//Thanx

Cole Campbell Cole Campbell · Accepted Answer · 2013-01-16T19:22:23

An old technique for doing this is to break your directions into two sets: those which involve moving across an edge, and those which involve moving across a corner. Assuming that north corresponds to the top corner of the tile, then the sets break down into the ordinal and cardinal directions, respectively.

You can then represent each set of directions as a 4-bit integer, where each bit corresponds to one of the directions. For each direction, set its corresponding bit to 1 if that direction requires a fringe, and 0 otherwise. This will give you a pair of values ranging from 0 (no fringing - 0b0000) to 15 (full fringing - 0b1111).

These two 4-bit numbers can then serve as an index into a list of textures. Arrange each texture in the list such that its index corresponds to the directions with set bits. For example, if your bit order is NSEW (North, South, East, West), and you calculate that fringe is required on the north and south edges, then your texture index would be 0b1100, or 12--so make sure that the texture with index 12 shows fringe on the tile's north and south edges.

All you have to do then is draw the tile's base texture, overlay it with the tile's edge fringe, and then overlay that with the tile's corner fringe.

Generate isometric tile map with special tiletexture

1 Answers