Update of /cvsroot/pdl/PDL/Graphics/PLplot
In directory sc8-pr-cvs1.sourceforge.net:/tmp/cvs-serv10705
Implemented PerlDL interface for the low-level fucntion plshade1. This allows
the example x15c.c in the PLplot sources to be fully ported to PerlDL.
With this addition, I generalized the *_callback/*_subroutine approach for
passing subroutine names/references to the PerlDL/PLplot API functions.
The plshade1 function needs three such subroutine arguments: defined, fill,
and pltr. For now, the fill argument is always passed as plfill to
c_plshade1. Inn part, the reason for doing so is that plfill is effectively
the only fill routine available in PLplot. Besides that, using a subroutine
which accepts piddle arguments (as the PerlDL plfill) would complicate the
code in pp_def('plshade1'). This may change in the future.