----- header of ivolume.pro extracted on: Fri May 31 15:31:08 2013
----- Documentation for /sware/com/idl-7.0/idl70/lib/itools/ivolume.pro -----

 NAME:
   iVolume

 PURPOSE:
   Implements the iVolume command line interface for the tools sytem.

 CALLING SEQUENCE:
   iVolume

 INPUTS:
   vol0, vol1, vol2, vol3 - Three-dimensional arrays of volume data.
   Zero, one, two, or four of these channels must be specified.
   All of the volume arrays must be of the same dimension.
   If no volume data is specified, an empty volume visualization
   is created.

 KEYWORD PARAMETERS:
   RGB_TABLE0, RGB_TABLE1 -
   Set this keyword to the number of the predefined IDL color
   table (0 to 40), or to either a 3 by 256 or 256 by 3 array containing
   color values for Vol0 and Vol1.
   If not specified, linear gray ramps are used in the volume
   visualization.  If a two-channel volume is specified, the
   volume visualization will use both color tables; otherwise
   it uses the first color table.

   OPACITY_TABLE0, OPACITY_TABLE1 - [3x256] array of opacity values.
   If not specified, linear ramps are used in the volume
   visualization.  If a two-channel volume is specified, the
   volume visualization will use both opacity tables; otherwise
   it uses the first opacity table.

   VOLUME_DIMENSIONS - A three-element vector that specifies the
   volume dimensions in user data coordinates.

   VOLUME_LOCATION - A three-element vector that specifies the
   volume location in user data coordinates.

   IDENTIFIER  [out] - The identifier of the created tool.

   Keywords accepted by IDLgrVolume may also be specified.

   In addition, the following keywords are available:

   AUTO_RENDER - Set to 1 to always render the volume.  The default is
   to not render the volume each time the tool window is drawn.

   RENDER_EXTENTS - 0: Do not draw anything around the volume.
   1: Draw a wireframe around the volume.  2: Draw a translucent box
   around the volume.

   RENDER_QUALITY - 1: Low - Renders volume with a stack of 2D texture maps.
   2: High - Use IDLgrVolume ray-casting rendering.

   SUBVOLUME (or BOUNDS)- Six-element vector [Xmin, Ymin, Zmin, Xmax, Ymax, Zmax]
   to specify the subvolume to render.

   All other keywords are passed to the tool during creation.

 MODIFICATION HISTORY:
   Written by:  KWS, RSI, February 2003
   Modified: CT, Oct 2006: Added TEST keyword,
       allow RGB_TABLE0 and RGB_TABLE1 to be Loadct table numbers.