This is a very commonly used English expression used to denote two opposites. It does not relate to glasses or anything of the sort but rather to outlooks or states of mind.
The expression is used to denote the difference between an optimist who would describe a glass as being “half-full” and a pessimist who would see it as being “half-empty.”
There is no consensus regarding the first usage of this expression although the first recorded citation comes in the form of a quote in The New York Times by Ronald Reagan. This quote reads “you can say it’s like the glass half full or half empty from the year 1985.”
It is suggested by psychologists that a person does not have to de described as either a “glass half-empty” or a “glass half-full” person but rather their choice regarding the description of this metaphorical “glass” can change depending on the situation and their outlook at the time.
An example of this expression in use can be found in a quote by comedian George Carlin who said “some people see the glass half-full. Others see it half-empty. I see a glass that’s twice as big as it needs to be.”