Tilemap Pixel Shader (aka "texture atlas" shader)

[MuddyMole]

For anyone unfamiliar with the concept, here's a little background info:
http://blog.tojicode.com/2012/07/spr...ps-on-gpu.html

So basically, you have an object the same size as your frame (I really ought to add scrolling support, so it only needs to be the size of the window), with two textures:
* a map image representing your game level, with 1 pixel per tile.
* a tileset image with the individual tiles, in a 16x16 tile grid.

The color of each pixel in the map image determines which tile from the tileset to draw at that position.

Anyway, here's my version: http://sdrv.ms/13aDqGN

The tileset image must be 16x16 tiles in size. Tiles are indexed from 0-255 (ordered left-to-right and top-to-bottom), using the red component from the map image only (unlike the example above which uses red and green).

btw: I realize there are many other ways to do the same thing, besides a pixel shader, but it just seemed like an interesting experiment.


EDIT: Ooops - it's still broken (thought I'd fixed it). If anyone can figure out how to fix it, it would be much appreciated...

[Looki]

Nice work, but I don't see why you're limitting yourself to 16x16 tiles. From what I can tell you only mod/div by that size, so there's no problem implementing it as parameter.

[MuddyMole]

Yeah, that would be very easy - but it's just a simple little demo at the moment. I might add stuff like that and scrolling later.

In the meantime, it's still not working properly on my netbook for some reason (uses the wrong tiles in some places) - even though it works perfectly on my desktop pc, and the netbook has never had any trouble with any other pixel shaders.


EDIT: Never mind - I think I've fixed it now. I'll add those other features tomorrow.

[Fanotherpg]

Looking forward this experiment.