The state of the game is displayed on a rear-projection screen. The Display module generates the graphics for this screen. It is a standard Netrek client with several enhancements. An RPC interface allows remote access to standard display parameters such as viewport zoom and pan, plus addition features for the Ogg That There such as remote cursor display, highlighting of game objects, and textual feedback to the user. Some of these features can be seen in Figure 3.2.
The Display also provides a high-level interface for game information. For Ogg That There this is used by the interpretor to retrieve game objects that appear near a given screen location and satisfy a list of grammatical constraints.