Re: [PATCH] New pm3d corners2color function

[sfeam (E. Merritt) <eam...@gm...>]

On Sunday, 07 October 2012, Petr Mikulik wrote:
> > However, the pm3d code currently treats NaN as if it were zero anyhow,
> > so as a practical matter the plot would not come out any different.
> >
> > The "with image" plot modes recognize NaN and do not draw the corresponding
> > rectangular pixel.  Should we make pm3d do the same?
> > I haven't looked to see how much work that would be.
> 
> I have tried
>  	set view map; splot 'a.dat' with pm3d
> and
>  	plot 'a.dat' with image
> and it was the pm3d style which skipped the point, not the image style -- thus 
> the opposite observation.

Very interesting.  Those were not the test cases I tried.
For image plots I had in mind the examples in 'imageNaN.dem', 
which plot using the commands

plot  $matrixdata matrix with image  # NaN pixel is omitted
set view map
splot $matrixdata matrix with image  # NaN pixel is omitted


While for the pm3d plots I used the last plot in "pm3d.dem"
after modifying Dima's new harmean4() function to return NaN
when appropriate.  

You are absolutely right that the simpler non-matix
'plot with image' command also needs fixing.

> Isn't it gnuplot who does not read it properly?

It seems so.
Image data is read properly in matrix mode but not (it seems)
in non-matrix mode.

I do not understand why your pm3d example works but mine 
does not. From inspection of the code in pm3d.c I see no
special case for NaN pixel values, so how does it ever work?
I had been thinking that a new test would be needed,
like this:
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@@ -911,10 +914,11 @@ pm3d_plot(struct surface_points *this_pl
 
                        if (pm3d.direction != PM3D_DEPTH) {
                            if (color_from_rgbvar)
-                               set_rgbcolor(gray);
+                               set_rgbcolor((unsigned int)gray);
                            else
                                set_color(gray);
-                           filled_quadrangle(corners);
+                           if (!isnan(gray))
+                               filled_quadrangle(corners);
                        } else {
                            /* copy quadrangle */
                            quadrangle* qp = quadrangles + current_quadrangle;
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
Yet your example works even without this change.  How?
Clearly I need to stare at this some more.

	Ethan


> with
> 
> 0	0	0
> 0	1	-1
> 0	2	-4
> 0	3	-9
> 
> 1	0	1
> 1	1	0
> 1	2	-3
> 1	3	-8
> 
> 2	0	4
> 2	1	3
> 2	2	0
> 2	3	-5
> 
> 3	0	9
> 3	1	8
> 3	2	NaN
> 3	3	9
> 
> 
> ---
> Petr
>