A novel approach to develop large-scale virtual environment applications using script-language

Modern Collaborative Virtual Environments (CVEs) are no longer developed as a one-piece to support specific applications such as online games, Virtual shopping, and E-health. In the traditional way, any modifications in VE applications require a service interruption in order to change both programming code and the supporting structure. As a consequence the ability to build and/or extend 3D VEs during the runtime becomes tedious task and requires long development time with advanced programming knowledge. Nowadays, it is important to offer an easy and rapid way for users and game developers to build and/or to extend CVE applications during the runtime without having the option to interrupt the system. In this paper, we propose a novel dynamic approach based on event atomic actions management, thanks to the state machine. We employ two different high-level scripting abstractions called class modeling and instance modeling. Class modeling controls what seems to be the simulation scenario, while, instance modeling controls objects and avatars behaviors in the virtual environment. Both class and instance modeling are implemented as a scripting plug-in and mastered respectively by atomic simulation and atomic behavior concepts. The atomic behavior concept is not only limited to object behaviors, it also handles the avatar facial animation parameters as defined in MPEG-4 SNHC standard. We evaluate the benefits of our proposed solution by describing a complex firefighter's game scenario. Through this scenario we explore the interaction between class and instance script modeling as well as the implication of atomic concepts on making code writing, when a VE application modification is required.