Feng Shui is a part of China traditional culture. It predicts and adjusts the house, home, business and natural environment through observation and experience summary, thus helping people get a better life and happiness.
In geomantic omen, glass and mirror are important objects, but their meanings and functions in geomantic omen are different.
Glass is a transparent material that can reflect light, but they can't really reflect people's images like mirrors. So from the perspective of geomantic omen, glass does not represent a mirror.