Re: pm3d and parametric function surface plots

[Johannes Z. <joh...@ze...>]

On Thu, Dec 02, 2004 at 12:36:39PM -0800, Ethan Merritt wrote:
> On Thursday 02 December 2004 09:27 am, Johannes Zellner wrote:
> > 
> > I just thought that coloring parametric surface plots according to the
> > computed z-Value is not reasonable or obvious at all.
> 
> I agree. 
> Then again, I have never needed to plot such a surface at all,
> so maybe I am failing to imagine a reasonable use.
> 
> > It would be 
> > reasonable to color it according to any function which depends on u and
> > v (the parametric variables).
> 
> Yes, that sounds much more reasonable.  It gives you the same sort
> of "4th dimension" that is available for plotting data from a file.
>  
> >     gnuplot> unset parametric
> >     gnuplot> splot f(x, y), color(x, y) w pm3d
> > 
> > But this time, the specification is ambigous.
> 
> I don't like the use of commas at all.
> Any syntax that uses commas to mean more than one thing
> is intrinsically ambiguous.
> By analogy to the existing syntax for data files,
> I think the above should instead be
> 
>       gnuplot> splot using (x):(y):f(x,y):color(x,y) 
> 
> which it may or may not be possible to shorten to
> 
>       gnuplot> splot using f(x,y):color(x,y)
> 
> > Introducing an option which forces function plots to have a color
> > function would solve the ambiguity.

and again what about:

    gnuplot> splot u, v, u * v w pm3d [at s] [function color(u, v)]

the options after pm3d beeing optional? -- The [at s] option is already
present, so why not another option which specifies the color function?
This way it would be just like any style option, where you specify
options to "styles":

    w lines lt 3 pt 1
    w pm3d function color(u, v)

What's the difference, in principle?
HBB: would that overload the syntax too much?

And it would be backward compatible. And it's /EASY/ to implement (I'd
just a look ...)

-- 
Johannes