fix: allow rendering shadows without realistic lighting

[Neptilo]

Description

Fixed SkyController so enabling castShadow turns on the sun light even when realisticLighting is off.

Motivation and Context

Consumers may want cast shadows independently of realistic lighting, but the sunlight visibility logic coupled the two, silently dropping shadows when realistic lighting was disabled.

Tested on Firefox, Ubuntu.

[airnez]

Looks good to me ! :)
Just add a condition on !view.shadows to avoid hiding date / time UI in RealisticLightingDebug.js in toggleDateTimeFolder function to avoid hiding date / time sliders when disabling realisticLighting in examples when shadows are enabled

[airnez]

🚀

[Desplandis]

I haven’t tested this PR yet, but from what I can see in the code, this is not a fix. We should consider it a new feature, since it may impact the default non-realistic use case.

As such, I don’t think it should be merged until we proceed with a proper release. We already have a ton of regressions, so let’s not add more to the pile.

I also veto the merge until we can confirm that this is not enabled by default and that it has no performance impact on the default non-realistic use case. Unfortunately, we don't have any regression-testing to assert this automatically since we do not have converged on #2714 (ping @mgermerie).

Since my comment above.

[Neptilo]

until we can confirm that this is not enabled by default

I confirm this is not enabled by default, and that, in examples that don't use it (e.g. source_stream_wfs_3d, vector_tile_3d_mesh), castShadow is never set, either on the SunLightLayer or on SkyController.

I updated the PR to make it work not only when setting the flag after construction, but also when shadows is already set to true in GlobeView's constructor.

shadows and realisticLighting are documented as independent options of GlobeView. The doc doens't mention shadows requires realisticLighting to work. Setting shadows: true alone just silently did nothing, with no error. Fixing that makes an existing flag do what it claims to do, without adding any new option or behavior.

[jailln]

@HoloTheDrunk so ? Have you verified the points raised by Desplandis? Can we merge? It's been open for 2 months now...