X N E C V I E W
---------------
A program for previewing NEC2 structure files (Unix/X-windows).

Copyright (C) 1998, Pieter-Tjerk de Boer

-----------------------------------------------------------------------
This program is free software; you can redistribute it and/or modify
it under the terms of version 2 of the GNU General Public License as
published by the Free Software Foundation.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
-----------------------------------------------------------------------

COMPILING:
----------
This should be trivial on Linux systems: just type 'make' in the
directory where the source has been unpacked.
I also supplied an Imakefile, which might make compilation on other
systems easier: typing 'xmkmf' will generate a Makefile, which can then
be used by 'make'.
You might want to change a few of the #define lines in xnecview.c, to
suit your tastes; see the comments.

USAGE:
------
The program expects to read the NEC2 input file from its standard input;
so typically, one starts it from a shell prompt like:
  xnecview < antenna.nec &
where antenna.nec is the file containing the NEC2 input.
A window is then opened, and the antenna drawn. Initially, the Z axis
points up, the X axis points to lower left, and the Y axis points to
lower right (unless you changed those settings in the source).
The view can be manipulated using the mouse as follows:
- click left mouse button: zoom in.
- click right mouse button: zoom out.
- move mouse while holding left button depressed: rotate.
- move mouse while holding right button depressed: move.
- click middle mouse button: go back to original view.
The program is quit by typing Q in the window.

LIMITATIONS:
------------
The present version (0.1) has several notable limitations:
- not all possible NEC2 structure elements are supported yet. Only wires
  (GW cards), surfaces (SM/SC cards) and reflections (GX card) are
  supported. If any non-supported cards are present, a warning is
  printed on standard output.
- surfaces are shown in a way which makes distinguishing between their
  'outward' and 'inward' sides impossible.
- the projection of the antenna onto the flat screen surface is described
  by only two angles, whereas three would be necessary to allow complete
  freedom of orientation. As a consequence, the projection is limited to
  those for which the z axis is in a vertical plane perpendicular to the
  screen. Fortunately, in practice, this doesn't seem to be much of a
  problem.

Contributions, comments and bug reports are welcome, please send them to
any of these addresses:
     Internet e-mail: pa3fwm@amsat.org / ptdeboer@cs.utwente.nl
Amateur packet-radio: PA3FWM @ PI8DAZ.#TWE.NLD.EU

