lighting gui enhancements

[Zach Pearson]

Per Elaine:

(1) only the "simple" preset restores light colors and directions. IMO for reproducibility they should all restore light colors and directions, at least for the lights they are using (e.g. "flat" has 0 key light intensity, so maybe it's OK it does not restore key light color and direction). Still I think it would be cleanest for the sake of reproducibility if they all restored all the lighting values as listed here:
<​https://rbvi.ucsf.edu/chimerax/docs/user/commands/lighting.html#simple>

But if you (TomG) think not all lighting presets should restore those things, let me know what exactly each one is supposed to restore so that I can correct the docs. You might want to consider also having the presets other than flat turn off silhouettes, but I'm fairly neutral on that.

The rest may be issues with the GUI:

Lighting tab:
(2) changing the preset, e.g. from simple to full, does not change the lighting intensities reported on the dialog even though the change is in effect according to what is reported by using the command "lighting" without arguments Maybe the sliders moved to the right place (not sure) but the values reported to the right of them don't change.

(3) maybe the preset name should be grayed out or change to something else (e.g. "none" or "--") as soon as you change some parameter, since the settings no longer reflect that preset.

(4) (minor quibble) the way a directionality arrow disappears when it goes behind the sphere is a little weird, you don't see it change orientation, just blip in and out of existence at the edge of the sphere.

(5) one time I changed the colors in the GUI but they did not appear to affect the main graphics window. That one time, when I then adjusted the directions, the GUI colors snapped back to white. I think Eric saw it, but I haven't reproduced this behavior, so maybe it is hard to get.

Shininess tab:
(6) using the "Sharpness" slider does not work. Error indicates incorrect keyword, should probably be "exponent" and not "specularExponent"

Depth Cue tab, leading to thoughts about the whole GUI:
(7) (minor quibble) the sphere is irrelevant to this tab, right? I.e. its appearance is not supposed to change? A possible GUI rearrangement is to not have tabs and instead put the shininess and lighting parameters all on the left at once. The color wells and blank space around the text could be a lot smaller. The lefthand text could be something like:

Lighting preset [blah]
Key intensity []
Key color []
Fill intensity []
Fill color []
Ambient intensity []
Ambient color []

Material preset [blah]
Sharpness []
Reflectivity []

Might make more sense to put GUI controls for the depth-cue parameters on the Side View instead, even though I they're controlled by the "lighting" command.

(8) If you use "lighting" commands directly to change anything, the dialog, or at least the Lighting tab stuff, does not update to show the current values.

e.g. if you show the Lighting dialog and then use

light color 100,0,0

the "Key color" color well in the GUI just stays white, the sphere shows white light, etc.

Regarding (7), my previously suggested dialog rearrangement, one part of that is that it would be very helpful to add a "Material preset" menu analogous to the "Lighting preset" menu because (A) we have material presets, and also because (B) it is well nigh impossible to get back to the initial value by moving the slider, and there is no type-in field.

I would also add another thing

(9) the title bar should be "Lighting" not "Lighting GUI" because Lighting is what you choose from the Tools menu and expect to see in the list of active dialogs at the bottom of that menu.

Additionally related to my previous comment #7, seems like there should be more material properties in the GUI than only two, one of which does not work (comment #6).