Re: surface elements for transparent_solids.dem

[Daniel J S. <dan...@ie...>]

I've placed a patch on SourceForge that changes the option name of 'hidden3d' to 'tileline' of 'set pm3d'.  Then hidden3d is enabled to work with 'with pm3d' by moving the hidden line function call to after the pm3d code in 'graph3d.c'.  Also, documentation makes the distinction between the two.

Please consider making this change.  It's a relatively short patch.  I think it more accurately reflects the plotting action.  (It takes a while for someone to realize that 'hidden3d' for 'set pm3d' and the 'set hidden3d' are actually two different things.)  It also moves things in the direction that Ethan suggested.  Future work would be to integrate solid surfaces into the hidden code.

The first example of 'transparent_solids.dem' I've left as is.  The second example (Kuen) I've changed to use the hidden3d.  I realize that messes up the intended illustration of transparent surfaces.  After the patch, someone can rearrange the demos.  (I'd suggest using Kuen surface as an example of illustrating speed and bad tile order in pm3d.dem... see my comments below about the current illustrations in pm3d.dem.)

Dan

...

Petr, in the demo 'pm3d.dem' it says 

set title "surface at view 130,10 (viewed from below)"
set pm3d
set palette
set view 130,10
set samples 50; set isosamples 50
set border 4095
unset surface
set pm3d at s scansforward
splot sin(sqrt(x**2+y**2))/sqrt(x**2+y**2)
pause -1 "Hit return to continue"

This example isn't technically something that looks to be view from below, is it?  Instead there is something discontinuous about it.

Also, the above plot and the one that follows it:

set title '"set pm3d scansbackward" makes this as viewed from above'

have border lines that appear kind of Escher-ish.

A little further along in the demo is the plot:

set title "set hidden3d"
set samples 30; set isosamples 30
set hidden3d
set pm3d
set surface
set view 50,220
set xrange [-2:2]
set yrange [-2:2]
splot log(x*x*y*y)

Notice, that prior to the patch I created, this plot did not have hidden3d present.  After the patch, it looks to have hidden3d, per the plot description.