This package provides a small collection of mostly rgl-based functions
for 3D data:

  contour3d     Uses rgl to render isosurfaces, or three-dimensional
                contours, computed by the marching cubes algorithm.

  image3d       Crude 3d analog of image() using rgl to plot points on a
		three dimensional grid representing values in a three
		dimensional array. Assumes high values are inside and
		uses alpha blending to make outside points more
		transparent.

  lines3d       Draws connected line segments in an rgl window. 

  parametric3d  Plots a two-parameter surface in three dimensions in
                rgl.  Based on Mathematica's Param3D

  slices3d      Uses tkrplot to create an interactive slice view of three or
                four dimensional volume data, such as MRI data.
