Is it still burglary of a habitation if door was open and you entered and didnt take anything?

No, this does not constitute burglary. Walking through an open door and taking nothing would simply be the Tort of Trespass with no criminal liability. Trespass is an act of physical invasion onto another person's property without consent or necessity. This seems to be what you described and it would subject you to tort liability in a civil law suit. Burglary, on the other hand, is the trespassory breaking and entering of another person's property with the intent to commit larceny therein. Although burglary does not require that you actually steal anything, it does require that you "break" in - which means that you must actually move a door or window to gain entry.