Is the glass half empty or half full? Depends on the last action taken.?

I.E.-If you are driving your car,you look and see the gas guage. Is it half E, or F? I believe that it is half E. Due to the fact that it is in the proccess of being used or drained. I.E -If you are filling the glass it is half full. If you are pouring out or drinking. It would be getting empty-er.
Hence the last action taken. agree or disagree?