Virtuality Builder II - On the Topic of 3D Interaction

this paper we present the Virtuality Builder II (VB2) framework developed at the Swiss Federal Institute of Technology for the construction of 3D interactive applications. First, we'll give an overview of the design concepts of VB2. Next, we'll concentrate on how users interact with dynamic models through direct manipulation, gestures, and virtual tools. More details on the rendering and modeling clusters are found in (Gobbetti et al., 1993), and more detailed explanations of the dependency maintenance algorithms, as well as on their use to implement tools behavior, are found in (Gobbetti, Balaguer et al., 1993). 1.2 DESIGN CONCEPTS VB2 is an object-oriented framework designed to allow rapid construction of applications using a variety of 3D devices and interaction techniques. As shown in figure 1, VB2 applications are composed of a group of processes communicating through inter-process communication (IPC). A central process manages the model of the virtual world, and simulates its evolution in response to events in the form of IPC messages coming from the processes that encapsulate asynchronous input devices. Sensory feedback to the user can by provided by several output devices. Visual feedback is provided by real-time rendering on graphics workstations, while audio feedback is provided by MIDI output and playback of prerecorded sounds. Rendering Application DataGlove Spaceball Mouse MIDI Sound EyePhone Rendering Figure 1. Overall structure of VB2 3 In order to obtain animated and interactive behavior, the system has to update its state in response to changes initiated by sensors attached to asynchronous input devices such as timers or trackers. The virtual world can be seen as a network of interrelated objects whose behavior is specified by the actions taken in res..