Re: [Plplot-general] Array out from plshades

[Arjen M. <arj...@wl...>]

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.

Regards,

Arjen