MonoGame Feature Wishlist

[nkast]

@willmotil

E,g, if you have a mesh with 6 vertices were vertices 0 to 3 make up quad 1 and vertices 2 to 5 make up quad2 then the shared uv coordinates at vertices 2 and 3 wont allow you to use two separate tiles in that mesh. This can be done with multi texturing and more data per vertice but then that starts to represent a whole unacceptably whole lot of data for all adjoining sides and possibly even more if the mesh is not comprised of grids.

So he was attempting to separate the quads and align them so that the edges of a quad 1 which is then made up off vertices 0 to 3 touch the ends of another quad made up of vertices 4 to 7 so each has its own separate uv components.

This would all be trivial if it were possible to attach uv coordinates to index data instead of the vertice data itself but as far as i know that’s not possible.

You could use a custom shader and a second texture to hold the UV data.
Here’s is how I think this could work:

One texture would be the texture atlas that contain the tiles (‘TileAtlas’).
The second will hold the TileMap.
You render a single quad with UVs from (0,0) to (1,1),
In the shader first you sample the TileMap (PointClamp), the four components would be a translation (.rg) + scale (.ba).
you take the UV modulo TileMap.Size, apply translation + scale to get the final UV for TileAtlas.

If all tiles in the atlas are the same size , then you can hardcode the scale factor in the shader and use the remaining 2 components (.ba) for a second tile layer.