1. A method of rendering computer-generated content on a handheld device, comprising: creating user-tracking data by tracking user face information, wherein the user-tracking data comprises information relating a position and an orientation of a user face relative to the handheld device; creating device-position data by determining a position of the handheld device, wherein the device-position data comprises information relating to an orientation of the handheld device relative to a physical environment the handheld device is situated; calculating rendering data using the user-tracking data and the device-position data; and displaying the computer-generated content on the handheld device according to the rendering data, wherein rendering of the computer-generated content is adjusted based on user movement relative to the handheld device and handheld device movement relative to the physical environment the handheld device is situated.