Orientation viewer needs axis labels #3599
Description
Is your feature request related to a problem? Please describe.
A rod at θ = 0º shows a circular scattering cross section since the long axis is in the direction of the beam. Rotating to θ = 90° places the length cross section in the scattering plane and gives rise to an anisotropic pattern, with the rapidly changing direction representing the length, and the slowly changing direction representing the radius. It should be clear from the tool which direction represents horizontal (x) and which represents vertical (y).
Describe the solution you'd like
Put x-axis and y-axis labels along the edges of the displayed scattering pattern.
Verify that θ=90° and φ=0° shows rapid fringing in the x direction (assuming the shape is a parallelepiped with long axis in the c direction, initially along the beam).
It would be useful to start the viewer looking down the z axis so that the scattering image is oriented like the detector on the beam line with x horizontal and y vertical. Start it with an angle θ=90°.
Place a, b, c labels on the edges of the box, corresponding to the length_a, length_b and length_c values in the parallelepiped model.
Since a box is symmetric about its axes, it is unclear which side is the front and which is the back. The sasmodels.jitter tool put a handle on one end of the box to disambiguate (though I never did verify the orientation with an asymmetric shape). [edit: Putting a, b, c with arrows in the direction of the positive a, b, and c axes is a better solution.]
I find the position of the angle values confusing. I would prefer the label for the bar to be e.g., θ=90° rather than putting the 90° value equidistant between the θ and φ bars. I'm constantly second guessing whether the value is associated with θ or φ. Similarly for Δθ.