VIEW an exploratory molecular visualization system with user-definable interaction sequences
VIEW is an exploratory visualization system for studying the structures of molecules. The system supports a high degree of complex user interaction with the image. Visualizations are constructed by selecting drawing tools from a library. Each tool uses parameters obtained from interactive selection of on-screen geometry by the user, and from a molecular database. The system is based on a tight coupling of on-screen geometry with the underlying database. Using these links, tools can create true-scale drawing elements that are constrained to database values. VIEW is highly extensible by the user or a paraprogrammer associated with the user. Drawing tools are written in a C-like programming language with constructs for managing databases, constructs for creating and altering geometry, as well as standard statements such as If-Else and For loops. An event-definition mechanism allows the user to describe actions to be performed when keys are depressed or dials turned. In addition, the user is able to specify conditional events actions that are to be taken whenever a user-defined condition becomes true. These conditions are automatically evaluated by the system as part of event processing. Such conditional events allow simple simulations to be readily programmed. Applications of conditional events have included animations of protein binding activity, and an interactive "flashlight" which highlights structures as a cursor is steered through a molecule. The system includes a development environment complete with a WYSIWYG editor, an interactive debugger, and a set of innovative graphical debugging features. VIEW has been installed for over a year in a protein crystallography laboratory at Duke University. Graduate students and faculty have used the system both for exploring molecular structures and for producing presentation graphics. These users have developed their own set of tools and made extensive use of the tool library. In January 1993, a beta-version of the software was released to a small set of laboratories in the US and Europe. It is now generally available.
