fast volume rendering library
VolPack is a software library for fast, high-quality volume rendering with
this features:
* Renders data sampled on a regular, three-dimensional grid.
* Supports user-specified transfer functions for both opacity and color.
* Provides a shading model with directional light sources, multiple material
types with different reflective properties, depth cueing, and shadows.
* Produces color (24 bits/pixel) or grayscale (8 bits/pixel) renderings,
with or without an alpha channel.
* Supports arbitrary affine view transformations.
* Supports a flexible data format that allows an arbitrary C structure to be
associated with each voxel.
