Example of using a fragment shader and two textures (graphics and data) to draw a large tilemap in a single draw call.

shader.frag is the actual shader drawing the tilemap, shaderx.frag, shaderxy.frag and shadery.frag show x, xz or y of the texture, to make it clearer how shader.frag works.

Graphicss load from tilemap.png, data texture is generated in C++.

Tile size is 32 (but can easily be changed by modifying shader and C++ both and doesn't have to be a power of two).