Re: [Gnuplot-info] maxima + gnupolot: 3D rendering bug?

[Stanislav M. <sta...@gm...>]

On Thu, 2010-12-09 at 12:11 -0800, Ethan Merritt wrote:
> On Thursday, December 09, 2010 07:53:12 am Stanislav Maslovski wrote:
> > > Replying to myself: actually, after reading some docs (and the code) I
> > > realized that it was a limitation of the rendering algorithm used by the
> > > gnuplot (a variant of painter's algorithm). So, I solved this issue by
> > > patching pm3d.c:pm3d_depth_queue_flush() so that sorting of quadrangles
> > > was done based on the average depth of 4 corners.
> 
> I don't think this is the best way to approach the problem.
> As Hans-Bernhard pointed out, _any_ simple-minded sorting on a 
> single Z value is going to fail for some configuration of triangles.
> The bigger the triangle, the more likely that any single Z value is not
> right for the whole thing.

BTW, just a little clarification in case if someone reading this has not
looked into the patch: the patch does more than just averaging the depth
of 4 corners, instead, it introduces a new pm3d option "corners2depth"
that allows for configurability of the depth sorting in a similar manner
as already existing "corners2color" option adds configurability to the
coloring.

--
Stanislav