Re: [Plplot-general] Array out from plshades

[Alan W. I. <ir...@be...>]

On 2005-03-25 13:21+0100 Arjen Markus wrote:

> Curtis Cooper wrote:
>>
>>> Hi,
>>>
>>> I'm using PLplot to produce pictures of longitude, latitude temperature
>>> maps for my planetary atmospheres research.  I first apply an orthographic
>>> projection to the lon, lat coordinates and use the grid so computed as the
>>> argument into plshades along with pltr2:
>>>
>>> plshades(temperature, clevels, fill_width, 0, pltr2, X, Y, 2)
>>>
>>> Temperature here is known at all longitudes and latitudes for which I have
>>> computed the X,Y projection matrices, i.e., T(lon, lat).
>>>
>>> This is just like example 16.  Now, the routine plots the map projection
>>> beautifully.  However, for further computations, I would really like to be
>>> able to extract the projected data, i.e., T in the X,Y coordinate system.
>>> What would be involved in modifying the PLplot source code to allow me to
>>> do that?
>>>
>
> Nothing:
>
> The function pltr2() is doing the actual coordinate transformation. You
> can
> call it yourself like this:
>
> for (i = 0; i < n; i++) {
>    pltr2 (x[i], y[i], &tx, &ty, pltr_data);
>    x[i] = tx;
>    y[i] = ty;
> }
>
> where pltr_data is the grid matrix.

It may not be much further help beyond what Arjen has already said, but
sparse documentation of pltr2 actually exists at
http://plplot.sourceforge.net/docbook-manual/plplot-html-5.3.1/pltr2.html .

Alan
__________________________
Alan W. Irwin
email: ir...@be...
phone: 250-727-2902

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); PLplot scientific plotting software
package (plplot.org); the Yorick front-end to PLplot (yplot.sf.net); the
Loads of Linux Links project (loll.sf.net); and the Linux Brochure Project
(lbproject.sf.net).
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