Re: smooth shading & terminal specialities

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

Petr Mikulik wrote:
>> My opinion is that this "gppsfile" variable should be eliminated.  
>> From what I understand, the purpose of this is a flag in the main code 
>> that indicates a PostScript comment can be added to the file for later 
>> use.  This is for the purpose of later running an awk script to look 
>> for repeated postscript strings and redefine them as shorter strings 
>> for purposes of compression.
> 
> 
> No; the term_api.h says:
> 
> /* Output file where the PostScript output goes to.
>    In particular:
>     gppsfile == gpoutfile
>         for 'set term': postscript, pstex
>     gppsfile == PSLATEX_auxfile
>         for 'set term': pslatex
>     gppsfile == 0
>         for all other terminals
>    It is non-zero for for the family of postscript terminals, thus making
>    this a unique check for postscript output (pm3d has some code optimized
>    for PS, for instance).
> */

Oh, yeah.  The postscript/latex split.  Forgot about that.


>> That will pretty much accomplish this "substitute long string with 
>> short string" approach.
> 
> 
> This is a completely different topic (code produced by PS_filled_polygon).

Yes, I think so.  That is the code I'm wondering about.

> 
>> * somewhere in the pm3d code would be this test to check if the pm3d 
>> drawing constitutes a flat 2D surface.
>>
>> * if flat surface, call the "image" terminal routine having a new 
>> projection angle input
>>
>> * For those terminals not supporting projected images, they can 
>> callback the routine that draws projected images with individual 
>> rhombus-es (or rhombi?)
> 
> 
> Thus you mean to automagically change "with pm3d" into "with image" 
> without knowing it to user? That's not a good idea I think.

Well, yes and no.  The point is, there are several images where the underlying image routine can be used for the plots that pm3d creates but the image routine is a much more compact manner of representing that plot.  (For example, the 2D map mode with rectangular grid is the perfect example.)  From the standpoint of the user, what is the difference in how that is represented?  (I'm thinking if there is a difference, myself.)

HOWEVER, there is still a slight difference in behavior that can't be changed.  It has to do with that "original grid points" demo you created.  The one that shows a 4x4 set of points results in a 3x3 set of colored rectangles.  I.e., the images on the pm3d.html page have to look exactly as they are regardless of whether the underlying plot is an image or rhombuses.  The advantage of the image is that in most display scenarios, I think, there is no introduced aliasing effect where a line shows up.  (Recall that "bug" from a few years back?)

Dan