Luff curve is just one of the methods of adding draft (shape) to the sail. When the sail material is laid out across the sail, shape is cut into the edge of each panel also. That is fairly straightforward; it gets much more complex when you add that shape into a biradial or triradial design.

BTW, it is fairly easy to relieve a hooking leach. A much harder problem to correct is leach gutter which looks just like a gutter running parralel to, and just inside, the leach. This is common in underbuilt sails which is more often encountered in high aspect ratio sail, such as self-tacking jibs.