NAME          read_gocad

AUTHOR        Ian Curington, AVS/UNIRAS Ltd.

TYPE          Data Input, C Subroutine

PARAMETERS
	      Filename Browser, GOCAD input file
              Choice buttons -  RESCALE yes or no
	      X, Y, Z  rescale float dials

OUTPUT
              geometry edit list

DESCRIPTION

  This is a data import reader module for the GOCAD (ASCII) file
  format. The GOCAD application models, edits, and describes
  3D geologic structures, containing horizon surfaces, 
  faults, and wells. The GOCAD application is authored by a
  group in Nice, France.

  This module reads the contents of one GOCAD file, and converts
  this to the AVS geometry data type, which can be sent to the
  Geometry Viewer for interactive display.

  Axis specific scaling is allowed by using the floating point
  parameters, supplied with dial controls by default.

  The module ignores all other lines from the GOCAD file except
  for vertices and trianges. It looks at the first character
  of every line. If the the line starts with
  "V", then it reads the id, and the position x, y, z.
  If the line starts with "T", it reads three index
  numbers for which set of verts to tie together as triangles.

  An example of a simple input file that will (minimally) work
  with this module is:

# GOCAD TEST FILE
V  1   0.  0.  0.1
V  2   1.  0.  0.
V  3   1.  1.  0.
V  4   2.  0.  0.
V  5   3.  0.  0.1
V  6   3.  1.  0.
TRIANGLE 1 2 3
TRIANGLE 4 5 6