Developing virtual worlds using toolkits and conventional programming-based approaches is a tedious, time-consuming, and often frustrating task. Too much learning of the toolkits and the basic development technology is necessary before the development can start. Even after that, it takes a long time to develop, test, and modify virtual worlds. At ISS, we are following a highly interactive and visual approach to virtual world construction, which allows virtual world designers to work with high-level concepts. This approach facilitates exploration in design and rapid prototyping. To achieve our goal, we are focusing on the following four base technologies: Bricks, a toolkit to support the development of virtual worlds; WorldNet, a toolkit to support the development of network-based virtual worlds; VizNet, a system that helps visualize a large collection of objects; and the Virtual Workbench, a crafting environment that uses virtual reality to build and manage objects.

Network-based virtual worlds allow multiple virtual worlds connected on a network to share information with one another. The development effort required to produce a network-based virtual world is quite large. The BrickNet toolkit simplifies this development by providing the standard facilities required by a wide range of network-based virtual worlds. It provides support for graphical, behavioral and network modeling of virtual worlds in an object-oriented fashion. BrickNet enables graphic objects to be maintained, managed, and used efficiently, and permits objects to be shared by multiple virtual worlds. In this paper, the architecture and implementation of BrickNet are described.