Decals are typically projected in 3d space, not UV space, so no - they shouldn't stretch. (although if you were to place a decal in the uvs directly, then yes they would stretch).
This is a great answer, thank you! I guess that if the baked texture or scanned texture is also stretched in the same way, it ends up looking right. The cons: in addition to tiling, wouldn't any in game real time decals, like blood splatters, also stretch? Is it safe to say that border aligned UVs are better for ofline…
Hi! I'd say aligning UV borders to pixel grid whenever it makes sense is a good practice for games, as it will minimize seams showing with lower texture resolution (mipmapping). With offline rendering, where one can use more, higher resolution textures it becomes less relevant imo. I believe stretching with decals depends…