I think these sayings can have a positive and a negative view depending on how full/empty the glass is and ect.
Glass filled below the rim: My glass will never be full enough/I spilled some of it./My glass will be full soon
Just an estimation but I figure it'd be something said by someone who will never be satisfied, or someone who felt they had it all and lost something. Or in the more joyous, positive view "My life is almost complete, but I need a little more."
My glass is full: I am fully satisfied with my life/or if your glass is full of something nasty then you feel you have a long unpleasant way to go.
I'd figure that a full glass would indicate a fully fulfilled life. Though I also think that this half empty/full factor can also depend on what is in the glass. So if someone has a full glass but it's something they don't like, then it's something that's gonna take a long unpleasant time to drink. So someone who maybe expects they'll have a long tiresome life/ or maybe their full life has gone sour somehow.