For version 2.2
---------------

libsciplot: new library.  Incorporate all functionality of VOGLE, PGPLOT,
and PLPLOT libraries; check into GLE.  Think about Guile, and Tcl/Tk, and
Python.  libsciplot will support contouring, but not 3d plots yet.

libsciplot: note when plotting a curve containing data points, symbols 
should be plotted _last_, after endpath() is called.

graph: librarify the plotting routines, and incorporate them in libsciplot.
N.B. need better clipping for filled regions (present gnuplot-style
clipping scheme is right for unfilled regions but wrong for filled ones)

libplot: Support Adobe Illustrator format (-T ai or -T ill), and CGM format.

libplot: add support for compound objects, Bezier cubic spline objects

graph: new option to put frame on top of plot, not vice versa
maybe automatic, if `plotting is real time' capability is set?

libplot: zero-length line segments not displayed correctly by Tek and HP-GL
drivers.  Fix this.

Comparatively minor things, for Versions 2.x
--------------------------------------------

graph: add legend support (need new --legend :string1:string2: option),
i.e. gnuplot-style `key'.  Maybe arbitrarily positioned arrows, text
strings also

old HP-GL plotters can't handle full range of coordinates (AutoCAD values
for range may not be good)

libplot: think more about `disconnected' line type.  Each defining point
should really be displayed as a circle of diameter equal to line width.

libplot: report failure-to-retrieve font (e.g. anamorphic problem) better.
Maybe print anamorphic message only when alabel() is called?

Also improve libplot error reporting: change libplot error handler to use
name of executable

spline, double: should ignore comment lines in ascii input (cf. graph)

graph: fix positioning of top labels, especially at large sizes

HP-GL/2 stick font size should be reduced?

Add comment() function, takes printable string as arg (no control chars)

PCL fonts for libplot: keep trying to track down slight differences between
HP-GL/2's font sizes and font sizes as specifed in the .AFM files
accompanying the Microsoft HP Font Set.

alabel, labelwidth: should not use clean_iso_string for Wingdings?

libplot: In X driver, need sanity check on font size: should switch to a
Hershey font if requested font is larger than display size.

ode: need no stack blowout

libplot: make meaning of "dotted", "dotdashed" etc. line types fully
device-independent?

Internationalization: think about removing strcasecmp (what if user called
setlocale i.e. set LOCALE env var)?  Similarly worry about . vs ,
everywhere, e.g. in PS files.

libplot: add a command to set miter limit for line joins, to the API

Hershey fonts:
1. add euro and cedilla; also embolden `times', > , < , etc.
2. Add support for Hershey indexical positioning on baseline?
3. Invert `glaze' glyph for EUC, also `therefore'

check into test/plot2tek.test (not currently run, seems to give
system-dependent behavior depending on rounding mode?)


Major Enhancements (Possible, Probable, or Certain)
---------------------------------------------------

libplot: C++ binding

libplot: redo X driver, to support window reuse (`persistence') by any
X Plotter.  Will require forking off an outboard process.

graph parsing: allow all command-line options in data files, on comment lines

graph: Write alternative parser for interactive version (gnuplot replacement).

libplot: add support for raster objects

libplot: support PGML output format

libplot: polyline hatching as well as filling

libplot: add interactivity (e.g. getloc()), during openpl()...closepl().
Need to translate back to user coordinates.  [For libsciplot, even
further?]  For Tektronix driver, implement GIN mode (need stty twiddling?).
Also need char input (cf. starbase).

libplot: write a version producing a bitmap format (e.g. PBM); use new
freeware rasterizer for type 1 fonts [t1lib, by Rainer Menzner; see
ftp://ftp.neuroinformatik.ruhr-uni-bochum.de/pub/software/t1lib ].

libplot: add the display list concept (would facilitate addition of
compound objects).  Once display list is there, support zooming in libplot
X driver [PS output via buttons?].  Add a `close window' button instead of
closing by a single mouse click.

libplot text string format: \mk..\rt etc. should be stack machine; include
overline, underline, radical etc.  Cf. Alan Hershey's typesetting.

Break out spline() as subroutine(s), cf. fitpack?  Similarly with plot
frame / axis drawing.  For this, check into NCAR Graphics package,
`autograph' routines.

libplot: spline the Hershey fonts

ode: extend parser to plot functions as well as solve differential equations

ode: need popen() for output; cf. gnuplot

graph: add `boxes', `steps', `impulses', `bars' plot types (as in gnuplot).
Boxes, bars should properly support --fill-fraction option.

Write a sort of pic2plot program, supporting all output types of course.

graph: add support for polar/spherical plots, 3-D (surface) plotting

spline: add support for smoothing splines as well as interpolatory splines?

Other needed math software:

	fitting capability
	contour plotting via level curves; also compute enclosed area
	surface plotting	(cf. IDL for plotting and contouring)
