I think you can make this precise by considering each texture pixel as a small square.
The texture is 256x256, so each pixel has width and height 1/256.
You want to map vertices to the *centers* of these squares.
Let delta# = 1.0 / 512.0 and then adjust by + or - this amount.
So (0, .5) would become (0+delta, .5-delta) etc.
The texture is 256x256, so each pixel has width and height 1/256.
You want to map vertices to the *centers* of these squares.
Let delta# = 1.0 / 512.0 and then adjust by + or - this amount.
So (0, .5) would become (0+delta, .5-delta) etc.