Is this a bug? Is this by design? Is there a workaround? I try to export .png images with perfectly upward looking images and that is where I noticed that also from those exported .png images the sky was missing.
There are two style settings you can change to affect this. There is a checkbox for “Show ground from below”, and there is a transparency slider for the ground color. If it is set to show and has low transparency, the ground will block visibility of the sky when looking up from below.
Hmm…this does indeed cause the sky to disappear. But it isn’t that the ground is showing. I set an outrageous green ground color with zero transparency. Looking up from below, I see that color. But your test script shows a whitish color that is not my ground plane color. Furthermore, add even a tiny increment in red or green of the direction vector and I see the sky color again! It seems there is either a bug or a deliberate design that applies only when looking exactly up the z axis from above the ground plane.
Here too. So Perspective+Bottom view shows the style Background colour if the Ground is off, but Parallel Projection shows the sky colour. I think Kengey found a bug.