[Octave-bug-tracker] [bug #58956] Empty plot for certain xlim / ylim settings

[Markus Mützel]

Follow-up Comment #25, bug #58956 (project octave):

@hg200: I'm very happy with the progress so far.
Your analysis sounds reasonable. I didn't try the patch. But from what you
describe, it seems to work reasonably well.
I didn't get the point about "cameraposition" though. Why would it make a
difference wrt projection if everything (including the camera position and
target!) is translated to a different coordinate system?
I also don't understand why lighting would be special?
All of these translations are internal to the rendering. None of them should
have any influence on the properties returned by `get(gca)`.
Or was your point the following?: The currently observed deviation between the
"cameraposition" in Octave and in Matlab doesn't matter as long as we only
support orthographic projection. But it will be important once we'd like to
implement perspective projection. That point however applies completely
independent of the used coordinate system.
Is the projection done by OpenGL or do we have to manipulate all object
coordinates to give the "illusion" of perspective projection? Anyway, this is
probably a better topic for a report dedicated to implementing perspective
projection.

Do you agree that it would make sense to move from a camera centered
coordinate system to a target centered coordinate system?
Would it be better to use an object centered coordinate system? (I guess
target centered like you described is the best choice and easier to handle.)

Re comment #23: The camera target is not necessarily the mean value of
xlim,ylim,zlim (logarithmically scaled axes!). And it is possible to set a
different camera target (see e.g. `demo camlookat`).

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