How to proceed with package documentation screenshots

[Oliver Heimlich]

I have recently started to implement plotting for the interval package. 
The on screen results looks very good. The generate_html package adds 
demos together with their output and figures in the function reference, 
which basically is a good idea, because a picture is worth a thousand 
words. Also I plan to use m-file scripts for the creation of figures for 
the package manual.

However, I am unsatisfied with the quality of the images that are 
generated and would like to do something about it. Could you please give 
me advice in which direction to go?

* The postscript export of GL graphics (especially in 3D) has some 
severe issues (bugs #44181, #45137), which makes the exported vector 
graphics useless and creates problems during conversion to rasterized 
formats.

* The postscript export of Gnuplot looks very promising, because it 
contains correct polygons which can easily (depending on their number) 
be edited. But there are also problems to solve with unwanted/missing 
lines, and—the biggest issue—the z order of some polygons is wrong, 
which also appears on screen.

* The png images are created by conversion of a postscript(?) 
intermediate format. Why are rasterized images not directly rendered 
with the GL backend.

* The kludge: I could use screenshots of the figure windows. At least 
they show a correct figure (with low resolution).

I have no GL programming knowledge so far, and the gnuplot backend seems 
to be deprecated. Is there anything useful I could do about above problems?