So, today when i opened hammer i was confronted by a box named Smoothing Groups. http://postimg.org/image/ltmtz6t9l/ And all my textures appeared white like this: http://postimg.org/image/sitdf7ell/ When i filter textures for only used textures only my used textures show up even though they appear to be white. I would really appreciate all help I can get.
In all the time I've spent using Hammer I have never, ever, ever had to use (or even learn how to use) smoothing groups. As far as I know they can safely be ignored.
Smoothing groups are useful for weird curved geometry but as far as I'm aware most cases don't need manual application. I don't even think the 3D Smoothing Groups view is used ever.
The only time it's useful is when you have a corner that's 45 degrees or less and you need to tell Source that it's a corner, not an embarrassingly low-poly curve. (By manually setting the stuff on one side of the corner to a smoothing group.) So if you're making a map like Foundry it'd probably come in handy.