In this paper I describe an interactive Gauss's law computer simulation using the GlowScript programming environment. The simulation calculates a point charge's electric field at locations on the surface of a Gaussian cube and displays the electric field in GlowScript's 3D graphics window. The point charge can be moved, and the electric field visualization will update dynamically. Students can use the simulation controls to record the electric field strength and direction, and then copy and paste the data into a spreadsheet in order to calculate the electric flux through the cube. The simulation can be used as part of a quantitative virtual laboratory to develop a student's intuition for electric flux and Gauss's law. The simulation can be accessed at https://sites.google.com/view/gauss/home.