land.grid

The art of programming tilemaps

= Types of tilemaps =

== The classic fixed-cell grid-map ==

This is the simplest form of a tilemap. Just define a grid and store a tile-id in each cell.

== Optimized fixed-cell map ==

There are various ways to optimize the simple tilemap to consume less memory. For example, quad-trees or similar techniques. A quad-tree can optimize away large empty areas, and makes it easy to have different-sized tiles as long as bigger ones have double the dimensions of smaller ones.

== Layers ==

Simply have multiple layers, one on top of another. This can have many uses, for example different tile-sizes and parallax scrolling.

== Non-rectangle ==

Popular types of tiles don’t use a fixed rectangular grid, but use hexagon or isometric maps. We’ll deal with both of them.

= The basics =

== Drawing ==

Assume, we have a fixed cell map. The x and y position of a tile can be calculated like this:

pixel_x = tile_x * cell_width
pixel_y = tile_y * cell_height

If the map data are stored as an array, and each map position just stores a tile number, we can retriece it like this:

tile_numer = array[tile_y * map_width + tile_x]

So now, we have all we need. We can draw the tile to its position. Doing this for all tiles in the map, we can draw the complete map.

== Picking ==

Something which is not obvious to do at first, but will be useful soon, is how to pick tiles out of a map. Thinking about it, it is quite simple to do. It is, in a sense, the opposite of drawing.

We have a (pixel) position, and want to know which tile lies under it.

tile_x = pixel_x / cell_width
tile_y = pixel_y / cell_height

== Collision ==

Since we know how to pick a tile from a position, we can easily do collision detection now.

= Non-rectangular maps =

== Isometric (diamond layout) ==

== Hexagon (diamond layout) ==

== Isometric (row or column shifted layout) ==

== Hexagon (row or coumn shifted layout) ==

For a wrapped grid, the returned position will always be normalized to
lie within the grid, even if the passed position or the view's scroll
position are outside.

land_grid_get_cell_position

Parameters: LandGrid * self, LandView * view, float cell_x, float cell_y, float * view_x, float * view_y

Given a cell position, return the corresponding view position, in pixels.

For a wrapped grid, the returned position will first be normalized to
lie within the grid, and then related to the view position. Try normalizing
the view's scroll position first (land_view_ensure_inside_grid) so it lies
within the grid, if you experience unexpected offsets.