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  Background

The GRASPweb  software is widely used in the structural biology community. It is mainly useful for generating contact surfaces of macromolecules (proteins, nucleic acids) with associated biophysical properties such as electrostatic potentials. This software takes advantage of SGI platforms capabilities for displaying. However for publication purposes one may want to produce high-quality pictures, e.g. featuring projected shadows, object texturing, and so on. Although GRASP does not (yet) provide direct support for any external rendering softwares, the molecular surfaces it generates can be saved in binary files for later use.

POV-Rayweb  is a famous, powerful and freely available software that renders photorealistic pictures on numerous architectures. It actually has become a real standard in many different fields, so that more and more softwares provide support for it. The POV-Ray syntax is text-based, that means portable and convenient in most cases. Unfortunately this is not efficient when parsing huge objects. For instance, molecular surface may be described as meshes consisting of thousands of triangles with their own textures. Furthermore, POV-Ray does not provide a built-in feature to do color interpolation within triangles, a feature that is commonly used to smooth different colors on the surface. While some scripts like the TRIMAP.MCR macro from the Chris Colefax's POV-Ray Include Files Pageweb allow to do color (or even texture) interpolation, they usually requires huge amounts of memory.

 


  Workaround

Pov4Grasp provides a simple and fast solution to overcome these "limitations". It implements new features to directly read GRASP binary surface files and to render it the way you want, as any other POV-Ray object. There's no need to deal with intermediate binary-to-ascii conversion utility (although you can also find the grasp2pov tool). Pov4Grasp allows you to save time (fast parsing), disk space (small file sizes), and memory (mainly with the internal support of per-vertex color smoothing). Thus it is especially recommanded for rendering animations of big and dynamical molecular surfaces.

This patch is merely an enhancement of the grasp2pov tool. The latter is originally based on Ethan Merritt's ungrasp which is provided in his Raster3Dweb  package.

 


  Future Plans

No plans until the release of POV-Ray 3.5

 



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