Well, you could simply use halfway positions.
Looking at the grass, you can tell that it is composed of two quads (with no backface culling, allowing to see the grass from any angle), both of these quads being centered on a block.
So, instead of defining positions with 0 or 1, you can define halfway positions with 0.5 values.
Let me know if this helps, I’m not sure if that’s the answer you need but maybe I did not understand the problem perfectly. Also, don’t forget to format your post with code tags, so that code is not displayed as normal text, which is really hard to read ( Using code tags properly - Unity Forum ).