Re: color box positioning for splot

[Hans-Bernhard B. <br...@ph...>]

On Sat, 13 Dec 2003, Daniel J Sebald wrote:

> Exactly.  I think this is what got me looking into margins, not only on 
> the X11 displays but also the PSLaTeX output.  There doesn't need to be 
> such a big margin there, UNLESS it has something to do with allowing 
> enough room so that rotating the image doesn't cause a different view of 
> the 3D graph to extend off the screen.  

I think that's what the original reason for that magic factor of 4/7 is
--- but there doesn't seem to be anybody left whom we could ask if that's
actually the case.  The only real hint so far was that 4/7 is pretty close
to 1/sqrt(3), the relevant factor that would achieve this.

> This could be the issue with why PSLaTeX doesn't work.  It might be
> basing its margins and background on the original 3D graph and not the
> rotated.  Consequently, it cuts off some of the graph.

The pslatex driver is rather a separate issue from that of screen usage by
3D plots.  The basic problem is that the bounding box output by all our
postscript drivers depends only on 'set size' (but not the ratio!) and
'set origin', which doesn't really describe the 3D plots well.

> Well, get rid of the large margins and adjust them based upon the 
> presence of a colorbox.  There's the solution.  

Getting rid of them may not be quite that simple.  In the effect, you'ld
have to change the actual size of the 'page' ex post, just like 'set size
ratio -number' now does it, and with all the ugly problems that creates
for the postscript bounding box, among others.

I suspect we have yet another missing terminal API capability on our
hands, here.  There's no way for the core code to tell the terminal driver
that it decided it wouldn't use all of the page size the driver offers.  
That's the *real* reason why the bounding boxes are usually wrong in 'set
size square -1' and 3D plots.  The driver peeking into the xsize and 
xoffset global variables used by the core is really an ugly kludge.

> OK, so you are saying the rotating colorbox in 3D is embarrassing enough 
> to warrant a quick fix.  :-)

Not quite --- it's Petr who wants this quick fix.  I just tried to provide
him (or whoever volunteers to do it) with the necessary insights on the
workings of our 3D code, since he expressed he couldn't seem to find out
how to actually do it.

-- 
Hans-Bernhard Broeker (br...@ph...)
Even if all the snow were burnt, ashes would remain.