ASSA, a Program for Three-Dimensional Rendering in Solution Scattering from Biopolymers

A program for three-dimensional rendering and interactive model refinement, ASSA, is presented. The program permits the simultaneous display and manipulation of low-resolution envelope models obtained from solution-scattering data and the crystallographic or electron microscopic models in the Brookhaven Protein Data Bank format. ASSA is coupled with the shape-determination program of Svergun, Volkov, Kozin, Stuhrmann, Barberato & Koch [J. Appl. Cryst. (1997). 30, 000-000], thus allowing one to monitor the shape determination process in real time. The program ASSA is written in C using the PHIGS+ standard for the three-dimensional solid rendering and the XView and XLib libraries for the menu-driven user interface. The system runs on a Sun SPARC ZX-20 workstation; a simplified IBM-PC version is also available.