What is the method or name or something like that when in first-person games for example holding a gun/item etc. in hand stays top of everything else in 3D?

I'm kind of new to 3D programming (used to make 2D games) and I'd like to have any links or information how to do that.
I hope you get my meaning.. it's like if you have huge 3D mesh in players hand and when you go next to wall and watch the wall, the mesh doesn't go "inside" the wall/scenery

EDIT: Oops! Wrong forum section, sorry!

To do that kind of "two layer" effect, the easiest way is to draw the main scene, then clear the Z-buffer, then draw the 'overlay' scene.

To do that kind of "two layer" effect, the easiest way is to draw the main scene, then clear the Z-buffer, then draw the 'overlay' scene.

Ohh it's that simple, well now I know that.
Also if someone knows some easy-to-follow books or documentation for a almost beginner in 3D games, would be nice too. Later on I can move on to more advanced mechanics