Re: [Plplot-devel] Wish list for the release

[Alan W. I. <ir...@be...>]

On Thu, 13 Dec 2001, Joao Cardoso wrote:

> On Tuesday 11 December 2001 23:50, Alan W. Irwin wrote:
> | (12) IMO, the most egregious bug for the plplot library shows up for x08c
> | with the non-smooth edges (missing triangles) to the hidden parts of the
> | plot for pages 5 through 8 (the 3D shade plot demonstration). If a C expert
> | here is wondering how they can chip in, it would be *wonderful* to finally
> | get rid of this bug.
>
>
> Yes, this worries me too, but it is not a matter of C expertise. I think that
> Geoffrey has already tried to correct it, and if I remember correctly he said
> "better to write it from the begining"

I believe the problem is actually pretty simple.  Just from looking at the
results, the current 3D shaded logic apparently makes a decision about which
(relatively large) triangle is hidden and which not, and has no facility to
refine the triangles shape and size so that they can smoothly follow the
line marking the edge of hidden regions.  We were up against a similar
problem for the excluded regions of 2D shade plots, but (see the last page
of x16c) Rafael found a working solution that involved a binary search
(IIRC) to refine the triangles so they smoothly followed the edge of the
excluded region.  Although he has stated his code cannot be directly used in
the 3D shading case, I am hoping his general idea can be used.  If so, it
should be a matter of a reasonably short effort to fix this with much thanks
for whoever came up with the solution.

> |
> | (13) dynamic tk and xwin driver.  (probably Joao).  My impression from
> | commented out parts of the code that I reviewed for the cgm driver is this
> | might be ready to go now that we understand exactly what is required in
> | the gd and cgm cases.  Every dynamic driver requires a link to libplplot
> | and some require additional links to their own special libraries.  Wouldn't
> | those special libraries just be the Tk library for the tk driver and the X
> | libraries for the xwin driver?
>
>
> The xwin and tk drivers can't be made dynamic.
>
> There is no problem with the xwin driver alone, but the tk driver (either
> static or dynamic) won't work with a dynamic xwin driver. The tk driver needs
> some functions that are in the xwin driver.
>
> The only solution, which is not elegant, would be to link tk.o and xwin.o to
> make tk.drv.

Would you please implement this solution?

>
> | I have probably forgotten some things so feel free to add to this list so
> | long as the project is reasonably short (a few days or less).
>
>
> This is an issue that worries me. You make a beatifull job testing plplot
> regularly, and you post your conclusions/bugs/requests. But we might be busy
> at the time, and your conclusions/requests becomes lost. I always archive
> your testing requests for latter usage, but most of the time I just forgot to
> use them.
>
> I think that we should start using some mechanism to correct this. A
> possibility will be using the "tasks manager",
> http://sourceforge.net/pm/?group_id=2915 , creating an entry for each driver
> and language binding. What do you think?

Probably that is a good idea for open-ended projects, but for this release
wishlist I am trying to to stick to short projects that can be finished with
a burst of concentrated effort.

BTW, I now regret my phrasing above where I said "I have probably forgotten
some things...." . I (like many here, I assume) have a long "ToDo" list of
possible fixups and issues we have discussed on this list.  So I never
forget, and I do come back to nag you again....;-)

Actually, what has happened with the wishlist is I made a judgement call
about what subset of the ToDo list involves projects that are short and
predictable enough (as opposed to open-ended) that it seems possible to
squeeze it in before the release. Others may have different views and I
welcome more discussion of this. For example, I will take the 3D shaded plot
bug (as shown by x08c) off the list if the general conclusion is the fix is
too tough to do in a short amount of time for a knowledgable C programmer.
If others want to add more to the list, that's fine as well.  The whole
point of the (amended) list though is these are the items the group feels we
should concentrate on before the release.  The wishlist I presented in my
e-mail was just the first stab at this priority list.

Alan