Re: contour labels

[Ethan A M. <sf...@us...>]

On Friday, June 21, 2013 08:56:09 am don taber wrote:
> I note that the revision to the contour labeling code
> in current cvs is a work in progress.  I find two problems:
> 
> 1. Contours are all drawn with the same linetype even
> when they are supposed to have different linetypes.
> Attached is a patch that fixes #1.

To the best of my knowledge this was deliberate, but I may be overlooking
a problem.  This bit of code, by the way, was not changed by the contour
labeling patch. So whatever problem you are seeing is independent of labels.

The idea is that if you give a plot command
   splot FOO with lines lt 0 
properties such as the dot pattern of lt 0 are maintained for all
of the contours jointly.  With your change, that "lt 0" would be
overwritten by whatever dash pattern was previously associated
with linetypes 4, 5, 6, etc. 

Was that your intention? 

> 2. When labels are placed on the actual contour lines
> (splot '' with labels), the labels seem very nicely
> placed.  Unfortunately, the contours themselves and the
> surface are missing.

I'm not sure I understand what you mean by "missing".

Do you mean that drawing the labels has the effect of
erasing the contour lines?  That would certainly be a bug.
The only thing I can think of that might cause that would be the
dimensions of the textbox (another new option that has only
been lightly tested).

Is the output you see from the demo equivalent that that on
the web site:

   http://gnuplot.sourceforge.net/demo_cvs/contours.html

If not, what happens if you say "set style textbox border transparent"?



On the other hand, if you mean simply that "splot ... with labels" draws
only the labels and not the lines, isn't that the expected behaviour?  
E.g.
  "[s]plot ... with points" only draws points.  
  "[s]plot ... with impulses" only draws impulses.
Why would labels be any different?

On the third hand, it is true that the code currently makes no attempt
to draw labels onto the surface itself, only onto contours drawn by
projection onto the xy plane.  This is mostly because early attempts at
labeling the surface looked terrible.  It is possible that the result
would be cleaner now that the "textbox" option has been added.

> I will leave #2 for  the instigator of the new feature. It is a good one.

Thanks for the feedback.
 
> Don Taber
> dt...@to...
>