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

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

Thanks, Maurice, for that clarification.  This project (as well as my wish
for dynamic tk and xwin drivers) is gone from the release wish list.  So
here is the revised list with some additional comments where progress has
already been made.

(1) Solve the python 2.1 segfault bug for example 9.  Probably release
critical.

(2) Get documentation to build on my new Debian system.  Release critical.

(3) Document what I did recently for the cgm driver configuration.
Hopefully, this will be the start of a new cookbook for the dynamic
(and static) driver configuration.

(4) Finish python examples and modify them to be exact replicas of the
C examples as a consistency check on the python front end.

(4a) Do the same for the tcl examples.

(5) gdimage extended example including all the things to make a colour image
work.

(6) Finish Java examples (with commented out API when that is not available).

Everything above this line is my responsibility.  Everything below is someone
else's responsibility, but I am willing to help with testing.
****************************************

(7) Perfect cgm driver.  DONE (thanks Andrew) except for some rare colour
and width bugs that will probably have to wait for the next release for
solution.

(8) Finish W98 and W2000 changes.  Apparently, Olof has made great progress
here (in fact he is now completely satisfied with the driver), and he
therefore intends to send me the definitive patch early next week.

(9) Get command-line parameter parsing to work for octave x examples.
DONE (Thanks, Joao).

(10) Java API (Geoffrey, once I get some more examples ready for him).

(11) Some refinement of the pyqt GUI.  Allesandro has made some progress on
the paging, but our discussion continues.

(12) There may be some more plimage changes Joao has in mind, but I am
not sure.

I very much appreciate how everybody has responded for projects below the
line (either by making excellent progress toward finishing them or else by
making good arguments why these projects shouldn't be on the wish list for
the release).  If anybody has other short projects in mind which they would
like to see done before the release, please feel free to add them to the
list (below the line, of course....;-))

Alan

email: ir...@be...
phone: 250-727-2902	FAX: 250-721-7715
snail-mail:
Dr. Alan W. Irwin
Department of Physics and Astronomy,
University of Victoria, P.O. Box 3055,
Victoria, British Columbia, Canada, V8W 3P6
__________________________

Linux-powered astrophysics
__________________________

On Sat, 15 Dec 2001, Maurice LeBrun wrote:

> I'm talking about the 3d shading algorithm, which is bolted on top of the 3d
> perspective (surface) plot.  Not the 2d shade-exclusion problem that was fixed
> previously.  These are way different problems.
>
> The 3d perspective algorithm follows lines of a constant coordinate.  It
> decides to draw or not-draw based on the condition: is it visible.  If it
> crosses from visible to not-visible or vice versa in one segment, the
> intersection point is calculated and the segment drawn from there.  Once
> that coordinate line is finished, the next one is started.  So you see, the
> original algorithm has no concept of "regions" at all.
>
> The new shading code that is bolted on top of this only worked if the triangle
> to be shaded is entirely visible.  If any of the three vertices is not
> visible, the triangle is not plotted at all, which gives rise to the visual
> effects you see in the demo.  I was able to work out boundary conditions for
> some cases and thereby eliminate some of the unshaded areas, but not all.
> It turns out to be surprisingly complex -- after a few initial successes I had
> lots of spectacular failures with spiky triangles drawn all over the screen,
> and had to give up.  At that point I concluded it might be simpler to start
> from scratch with a published 3d shading algorithm.
>
> --
> Maurice LeBrun    mj...@ga...
>
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