PRAGMATIC VEX 1 | LIMIT SURFACE SAMPLING | MOVING POINTS TO THE SUBDIVISION LIMIT SURFACE
There is a very practical use of the limit surface to figure out where a point is on the subdivision limit surface.
Imagine a character head like the one we were using, and you add a lot of detail to it, just like what we did before using adaptive subdivision.
That sounds all good in action, but what we are missing is the future projection of the same geometry, by additional subdivision, either as a post operation before exporting out the geometry, or as a render time operation.
In any case, this will result in the areas where there is added detail, to be flatter than before, even though it's not the case without adaptive subdivision.
Because if you recall, we were using Catmull-Clark subdivision algorithm, which will keep the original geometry nice and smooth.
But in other cases where you might have additional detail using algorithms such as Bricker, it might result in the areas where there is added detail to be flatter than before.
But we don't necessarily want this. What we want is to create detail without disturbing the future subdivided shape of the geometry.
So how can we do this?
Evaluating attributes at the subdivision limit surface gives us a way out.