Sky atmosphere gets brighter when the sun is offscreen in HDR mode

[lilleyse]

If you look carefully the sky atmosphere gets brighter when the sun is offscreen. I captured this gif on the globe-alpha branch where it's more noticeable.

Sandcastle

Here's the results of my investigation so far:

When the sun is onscreen the sky atmosphere gets rendered to the sun's post process framebuffer. It turns out the framebuffer uses 8-bit color always, even if HDR is enabled. I thought changing the pixel datatype would be enough to fix the problem but the sun post process just draws a black box (ignore the blue spheres). I didn't want to spend too much time investigating right now this but if anyone picks it up in the future here's my in-progress diff: sun.diff.txt.

[jjhembd]

@lilleyse I can't reproduce after #10063, although I'm not quite sure if I'm testing correctly. Are we ok to close this?

[lilleyse]

It's still there, but more subtle since the atmosphere ring is smaller.

Also, I needed to update the sandcastle because it was using an outdated API. Here's a new sandcastle.

sun-globe-translucency.mp4

[lilleyse]

This is also low priority, so I'm just going to close it