GUI rendered dark in some systems

[quarkytale]

The GUI is loading darker for some systems.

Wiki GUI:

Darker:

And really light:

Need to investigate what's causing this.

Notes from previous discussions:

• Possibly due to different driver versions, if the driver very out of date.
• No errors in OGRE logs

@WilliamLewww please add your findings too!

[mabelzhang]

Original discussion from #186 (comment)

@WilliamLewww if you could ticket something upstream in osrf/gazebo with your troubleshooting so far and tag it here, that'd be great!

[WilliamLewww]

I think that this issue has something to do with shadows. I was able to reproduce the same effect on two different machines where one would render everything lightly (light system) and one would render everything dark (dark system).

When digging into the shaders for the light system, I was able to tinker with the shadow specific parts to get a similar result to the dark system. I'm thinking that the dark system is somehow rendering shadows over every surface while the light system doesn't render the shadows at all.

[bsb808]

Wow - that is a very subtle bug to track down - nice work!

[mabelzhang]

I'm surprised if this is the first time it's been discovered though, if there's nothing unusually specific about the way lights are used in the DAVE worlds - are they? Maybe there's a local fix.

I found this issue - is it related? gazebosim/gazebo-classic#2686
There are a few shadow-related issues in osrf/gazebo
https://github.com/osrf/gazebo/issues?q=is%3Aissue+is%3Aopen+shadow
I'm just looking to see if there's already an existing ticket about it, otherwise the troubleshooting would go to a new ticket upstream.