Thread: XYZ to screenX, screenY

Like in many games, text is above a player's head that usually has their character's name and healthbar etc. I was wondering how to take the 3d coordinates of the player and make them into screen coordinates. I'm guessing I'll have to do something with the camera, because taking just the XY from the 3d XYZ wouldn't do much good.

Could this also be used....lets say for an NPC in an MMO where they sort of "light up" when you hover over them with the mouse? I might not do that. I might have something go over to the NPC and hover over them. ex. Navi from Zelda: Orcarina of Time, she floats around nearby people when you "z-target" them. I want to do the same thing except with "mouse hovering".