I’m trying to implement Wang tiling with shading nodes and there is a couple of things I don’t understand.

If I connect the UV (or any coord source) from a Geometry node directly to the vector input of a Tex node then everything looks fine. If I run the coords through any math or mapping node (even if the mapping is an identity transform) in between the Geometry node and the Tex node then the image looks terrible  missing pixels, just generally ragged.

If you use a Geometry node with Global coord input to a Tex node then the mapping appears to be (1, 1) to equal one tile of the texture instead of the (0,1) range for UV mapping. It also seems if you run UV coords through any math or mapping nodes you have to multiply by 2 and offset to get the correct mapping.
If anyone can clue me in to what’s happening or point out what I’m missing, I would appreciate it. Ill post a blend once I figure out how. (first post)
Thanks