Enhancement: Speed limits overlay - show marker to indicate underground segments?

[originalfoo]

From #1322 (comment) :

Train Tracks works too but for underground it requires switching with PageDown to show signs. They probably forget about that, maybe add tiny sign or v so notify that something is there or another toggle to always show everything

[kvakvs]

There is code to show underground segments with arrow down. We just don't draw them but should you render them, the arrows will be visible once again.

[originalfoo]

            if (segment.IsBothEndsUnderground()) {
                render.DrawSmallTexture_TopLeft(RoadUI.Instance.Underground);
            }

[originalfoo]

Underground segments are currently excluded from the cache when not in underground camera mode - see: ShowSigns_RefreshVisibleSegmentsCache()

Rather than excluding them from the cache, we could add a bool isUnderground_ to struct CachedSegment.

I'm already updating the overlays code to pass a CachedSegment (rather than it's two properties split out) to the rendering methods, so that isUnderground_ will be available and actionable during rendering (this also means we don't need to recheck for underground again in the render methods).

Overground segments will still be excluded from cache when camera is in underground mode.

[originalfoo]

Just leaving this here for future reference :)

Singleton<TransportManager>.instance.TunnelsVisible = true;

[originalfoo]

[originalfoo]

[originalfoo]

Could potentially show down arrow icon and when hovered still allow speed set (maybe even show the current speed limit icon on hover)?

Or have it so clicking the down arrow switches to undeground view?

[kvakvs]

Could potentially show down arrow icon and when hovered still allow speed set (maybe even show the current speed limit icon on hover)?
Or have it so clicking the down arrow switches to undeground view?

We already have tools for switching underground view, its Pg Up, and Pg Down. Making more interactable markers is not useful for locations where more than 2 roads overlap (tunnel + bridge + some ground road), we tried to declutter screen and hide signs, instead of adding more signs. If you want to display some info in the underground markers, at least don't make them interactable