Hi Alan
Thanks, I hadn't seen this function I will give it a try. It might be useful to mention this in the plmap documentation for other users who want something more general too.
Thanks again

From: Alan W. Irwin <irwin@beluga.phys.uvic.ca>
To: phil rosenberg <philip_rosenberg@yahoo.com>
Cc: "plplot-devel@lists.sourceforge.net" <plplot-devel@lists.sourceforge.net>
Sent: Monday, 7 October 2013, 17:47
Subject: Re: [Plplot-devel] plmap no user data

On 2013-10-07 08:01-0700 phil rosenberg wrote:

> Hi

> I've just been sorting out plotting some transformed map data - in
this case plotting data on a globe as would be viewed from space.
After writing a transform class I realised that there is no void*
parameter to pass transform data to plmap and no void * parameter of
mapform. Am I missing a way to be able to do this?

> It would certainly be useful in the same way as for other
transforms. In the scenario above there are obvious benefits to having
such a feature as I'd be able to create a generic transform and be
able to pass a class or struct containing details about the satellite

> But I guess this is an API change, unless anyone would be happy to
have a second version of the function with different parameters.

Hi Phil:

The documentation of plstransform says that the data parameter can be
used to pass required extra data, and the same general transformation
method is used in a number of other cases as well, e.g., the pltrl and
pltrl_data arguments of plcont, plshade, and plshades, and plimagefr.

I may be missing something, but I am currently wondering why
this transformation method not general enough for your needs in

this case.

Alan W. Irwin

Astronomical research affiliation with Department of Physics and Astronomy,
University of Victoria (astrowww.phys.uvic.ca).

Programming affiliations with the FreeEOS equation-of-state
implementation for stellar interiors (freeeos.sf.net); the Time
Ephemerides project (timeephem.sf.net); PLplot scientific plotting
software package (plplot.sf.net); the libLASi project
(unifont.org/lasi); the Loads of Linux Links project (loll.sf.net);
and the Linux Brochure Project (lbproject.sf.net).

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