Re: 'nohidden3d' option behavior

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

On 05/23/2016 10:52 PM, sfeam wrote:
[snip]
> Can you describe what it is you are trying to plot, rather than listing
> things that don't work?   I am failing to understand why you would ever
> select hidden3d and then draw a surface that doesn't use it.
> What is the goal?

I looked through the code a bit.  Attached is a short patch that allows 
LINES to continue onward and corrects what I think is an oversight.  To 
test, apply the patch, compile and then run something like:

set hidden3d front nooffset
splot 20*sin(x*y)/(x*y) with lines, x+y with linespoints nohidden3d
splot x+y with lines nohidden3d

This should show lines now (but isolines are missing and I can't figure 
out why), and in the second splot give a warning but continue on plotting.

The reason I think it should be the following (or no test at all, see below)

     /* These are handled elsewhere.  */
     if (plot->has_grid_topology && !plot->opt_out_of_hidden3d && hidden3d)
	return;

is that if one looks at where the plot3d_lines_pm3d() function is called 
in graph3d.c, there's a check on opt_out_of_hidden3d:

		if (draw_this_surface) {
		    if (!hidden3d || this_plot->opt_out_of_hidden3d)
			plot3d_lines_pm3d(this_plot);
		}

So, there is a more stringent test within the subroutine than there is 
in the calling code without the change I'm suggesting.  Note that the 
same sort of setup exists for plot3d_points(), and there is no test on 
the hidden property within that routine.  Similarly, there probably 
doesn't need to be a test at all within plot3d_lines_pm3d() either.  At 
least one of the items is already confirmed prior to being called.

Well, that's about all the change I would want to make for this.  If the 
attached changes make things clear and seem worth pursuing, I will 
create a bug report.

Dan