Enhance show in vis.py

[winksaville]

I was using show in vis.py to create a png and discovered that there was no way to designate the ViewUp normal. So I created PR #1837. But I than discovered that the PR was wrong as I wasn't handling None correctly. While revising the PR it seemed to me the implementation of show didn't feel right and also there were other useful parameters not being passed. So I'm creating this discussion thread to talk about what should be done.

First off, by "feel right" I mean that ResetCamera is not called if position or focus are passed. That seems odd as ResetCamera initializes many things and it seems to me the camera parameters should be consistently set regardless of whether you're doing relative or absolute positioning.

As a start I've created another Commit which always invokes ResetCamera and I added parameters:

• viewup: which I wanted
• azimuth: completes the roll + elevation relative operators
• clipping_range: completes the view frustum

Also, according to this VTK ResetCamera Orientation example there are also 3 other relative operators which are missing, should they be added as parameters to show?:

• SetRoll
• Pitch
• Yaw

[winksaville]

Should I just create a from the commit I pointed to above?

[adam-urbanczyk]

Sure, why not. But please keep things minimal and expect some rework.

[winksaville]

I've created PR #1855 and adding a new test and it has passed all checks and there are no conflicts, so it ready for review.