1. Is the reason we have the border at all to do with subpixel rendering? My intuition is that we have the border because if a pixel maps to the edge of the texture, such that it actually tries to sample outside the texture when doing subpixel rendering, we don't want to simply use the same color as the inside pixel that is sampled, because then we will still have aliasing when sampling from the texture edges; however, by having a 1px alpha border we get what we want, since anything outside of the texture is technically completely transparent and should thus blend with a fully transparent pixel linearly. is this right?
2. Casey also mentioined here:
that the issue with this method is mipmapping, but I have no clue why that is the case? i guess it's just because your border starts to blend, which then messes up the edge sampling, hence why border thickening is the solution, but I don't really get his digression into how mipmapping is always wrong by default because of the choice of (0,0) at the edge of a texture as opposed to the "half pixel boundary (not sure exactly what he means here)"