It uses GL or OpenGL and can be compiled with Mesa. VMD is designed for the visualization and analysis of biological systems such as proteins, nucleic acids, lipid bilayer assemblies, etc. X-based Image processing Tools and Environment. It allows the searching and generating symmetry equivalent parts of fragments, gives bond lengths, angles, torsion angles. XPMA can read in a maximum of 1999 atom positions.
Extensive documentation is also available in postscript format.