Re: Plot into an array

["Richard G. French" <rfrench(at)wellesley.edu>]

Dennis Boccippio wrote:
> 
> >
> > > does somebody know, how I can plot a function into an array, not into a
> > > window? Or can I get the array of the image of a window for saving as a jpeg
> > > or gif?
> >
> > Write into a pixmap window (a window in memory):
> >
> >    Window, /Pixmap, /Free
> >    Plot, myfunction
> >    array = TVRD() ; or TVRD(True=1) on 24-bit display
> >
>
**** I have tried doing this over my cable modem, and it takes bloody
forever
to do TVRD() for a large pixmap over the internet to my remote
workstation.
Another problem is that the maximum memory size for a pixmap is limited
by
the video monitor, NOT by the RAM on the computer itself, as I
understand. Both
of these have really hobbled me for my particular application.

> IIRC, David's suggestion below of using the Z buffer is more efficient
> (don't know why) and greatly reduced the bottleneck, though I could be
> wrong...
> 
> > Or, write into the Z-graphic buffer, if you want
> > to be assured of having a 2D array:
> >
> >    thisDevice = !D.Name
> >    Set_Plot, 'Z'
> >    Plot, myfunction
> >    array = TVRD()
> >    Set_Plot, thisDevice
> >

**** I have not tried this yet, but am I correct in thinking that a Z
buffer is part
of RAM, and not part of the memory of the display? If so, then I could
avoid all
the network traffic involved in TVRD() from a pixmap, and that would be
ideal.
I'll give it a try next time I have a chance, but I thought someone
might know the
answer to this - is Z buffer memory attached to the computer (I hope
so!), or to 
the monitor?

Dick French