Re: Odd behavior of "set border" and "splot"

[Hans-Bernhard B. <HBB...@t-...>]

Am 17.01.2020 um 21:58 schrieb Dima Kogan:
> Hi. I found something odd. Not entirely sure it's a bug.
> 
> I'm running the latest gnuplot from git (as of today), but this behavior
> isn't new.

Far from it, actually.  This behaviour has been in gnuplot essentially
forever.

These short verticals are not the ones controlled by "set border".  The
easiest way to visualize this is actually not to try and _disable_ them,
but to turn them all _on_, and compare what you get:

	set xrange [-10:10] ; set yrange [-10:10]
	set zrange [-100:150]
	set multiplot layout 2,1
	set border 15 ; splot x*y
	set border 255 ; splot x*y
	unset multiplot

Note how the activated border verticals reach up all the way up to
z=150, whereas the default ones get only as far up as the surface
itself.  Which, coincidentally, is exactly how those are controlled: if
the corners of a plotted surface mesh lie point exactly in the corners
of the x-y range rectangle, splot draws verticals from the corners of
the xyplane up to those points.

To turn off these shorter verticals while keeping any borders on, you
have to bend them out of the vertical, i.e. make the x-y-plane corners
differ from the corner positions of the dataset.  For data splots, you
can grow out the axis ranges a bit; function splots may have to be
switched into parameteric mode (or pseudo data plots) to allow the same
change, e.g.:

	set parametric
	set urange [-9:9]; set vrange [-9:9]
	set border 15 ; splot u,v,u*v