When plotting 3d points after calling "set view equal xyz " the plot is centered such that the bottom of the plot is in the center of the graph. That is: the point around which the plot can be rotated and zoomed is at the bottom. Thus, when you want to see the complete graph it covers only half of the window. This happens for example with the following plot:
set view equal xyz
set ticslevel 0
1 2 -10
3 1 -10
1 2 -2
By adding a line of code to the do_3dplot function in graph3d.c the plot center becomes centered in the window. This patch adds this line of code.
see https://groups.google.com/d/topic/comp.graphics.apps.gnuplot/btt9MccHrvs for a discussion on this patch.
see http://obooij.home.xs4all.nl/nerdspul/gnuplot/index.html for some screen dumps of the results.