A mixed reality system that includes a head-mounted display (HMD) that provides 3D virtual views of a user's environment augmented with virtual content. The HMD may include sensors that collect information about the user's environment (e.g., video, depth information, lighting information, etc.), and sensors that collect information about the user (e.g., the user's expressions, eye movement, hand gestures, etc.). The sensors provide the information as inputs to a controller that renders frames including virtual content based at least in part on the inputs from the sensors. The HMD may display the frames generated by the controller to provide a 3D virtual view including the virtual content and a view of the user's environment for viewing by the user.