Simplify gridline intersect callbacks

[gzotti]

Description

Issue #3688 describes a tiny problem in the gridline manager's labeling of equatorial coordinates.
I tried to fix and saw quite a bit of elaborate code was not even required. Or was it?

During development of this branch I will try to remove that possible bloat code also for the other grids.

Fixes #3688 (issue)

Screenshots (if appropriate):

see #3688

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• This change requires a documentation update
• Housekeeping

How Has This Been Tested?

Test Configuration:

• Operating system: Win10, Win11
• Graphics Card: Geforce cards (irrelevant)

Checklist:

• My code follows the code style of this project.
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation (header file)
• I have updated the respective chapter in the Stellarium User Guide
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules

[github-actions]

Great PR! Please pay attention to the following items before merging:

Files matching src/**/*.cpp:

• Are possibly unused includes removed?

This is an automatically generated QA checklist based on modified files.

[10110111]

What is lon supposed to mean? The longitude of the observer on the planet? Why should it affect the label?

[gzotti]

lon/lat (longitude/latitude) seem to be the interface points of screen intersection (?) in general spherical names. I have not gone further today, but at least in the equatorial grid they seem not to be required. Or I am missing something important.

[alex-w]

OK, all tests from my side are passed

[gzotti]

Brr, and I just discovered errors. Switch to decimal degrees! Not sure what's happening.

[alex-w]

Brr, and I just discovered errors. Switch to decimal degrees! Not sure what's happening.

Oops... hour angle should be always in hours - this bug exists in the current release too

[gzotti]

Not necessarily. It's really user's choice. See SHA for navigators.

[alex-w]

Coordinates in infobox and in grids should be consistent

[gzotti]

please test with all grids and settings (decimal numbers etc.)

[alex-w]

Hour angles should be measured in hours by definition, not in degrees

P.S. Of course in the current master I see same problem and this is bug IMHO

[gzotti]

Do you mean decimal hours? I am not aware of any use for that. Navigators and maybe others (surveyors?) may prefer decimal degrees for hour angles. This branch/fix should however only change the previous behaviour of a spurious 0 for 12h/180°. Given the simplifications, I hope I did not break other grids now. (I guess a lot of bloat was to mitigate the original problem)

[github-actions]

Hello @gzotti!

Please check the fresh version (development snapshot) of Stellarium:
https://github.com/Stellarium/stellarium-data/releases/tag/weekly-snapshot

[github-actions]

Hello @gzotti!

Please check the latest stable version of Stellarium:
https://github.com/Stellarium/stellarium/releases/latest