Half empty, or half full - witch one is it?

Easy as pie. 2 diffrent answer's to that.
1) The person, who think's all the time negativly, will answer to that half empty.
2) When pouring the liquid into the glass, and then , when the person will quit doing that, when the glass isn't full yet, then a person can say, that the glass is half full. Half full is said, when you have a full glass of a certain liquid, and only drink / pour, until to the half of the glass, then a person can say, that the glass is half empty.