[Octave-bug-tracker] [bug #57553] ML/Octave visual differences in plotting

[Markus Mützel]

Follow-up Comment #33, bug #57553 (project octave):

Thanks Rik for pointing those out.

The lighting in "demo isocaps 1" looks more natural to me in Octave than what
it does in Matlab. It looks like the lighting is from the wrong side in
Matlab.
Looking at the demo, there seems to be an error in the direction of the set
VertexNormals. That they are set manually at all seems to be a relic from when
Octave didn't calculate the normals automatically. I'll prepare a changeset
for the demo when I find some time.

"demo isonormals 1" shows that Matlab doesn't do a perfect job as well when it
comes to the sign of the automatically calculated normals. I don't know
whether it is worth trying to perfectly mimic Matlab in this case. After all,
in this particular case, Octave seems to do a slightly better job.

IIRC, we talked about "demo light 10" before. To be honest, I don't know what
Matlab is doing in this case. Reading their documentation for "reverselit", I
would expect that the top and bottom subplots on the left look exactly the
same (what they do in Octave). Anyway, the lighting in the top left subplot
looks unnatural in Matlab to me.
Apart from the lighting, there might be a different bug: The patch seems to
close strangely in Octave. It looks like there is an additional triangle (or
polygon?) in Octave that I wouldn't expect (and that isn't there in Matlab).

It looks like there is no specular reflection for "EdgeLighting" in Matlab
(demo light 12). Did that change with Matlab versions? Do we want to follow
that change?

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