Been a while for this thread.
I tried to implement the patch at the beginning of this thread with little success. But that made me take a good look at the code. At first I just tried to look for where the appropriate lines from the files needed to be located. Then I tried to get a copy of the code from back then and see if I could get that to work. I was able to build it but never quite got it working right. The more I looked at the code, the more I seen that the code for dynamic cloud shadows was disabled and it was a newer version of that patch.
I was successful at getting the code reactivated and for my hardware, it seems to work fine. It doesn't work well with VT's. A lot of artifacts. I can't tell if it would work with split textures cause my laptop won't even try to use textures over 8k. Thats the limit. With VT"s, I get the artifacts mentioned in the code documentation.
I updated the graphics driver a few weeks ago and discovered that it supports openGl 4.0. That got me looking at the API and there may be another way of rendering cloud shadows with newer machines that support that is > 4.0. I'm gonna look into this. Never know.
From what I got activated with the latest svn, I can run 8k textures with the "dynamic clouds" without any artifacts that I can see.
Here is a screenshot with clouds shadows on.
Here is the same shot with cloud shadows off.
These cloud shadows do change with the lighting conditions.
After a driver update for the laptop I got, Celestia's openGl info reports 4.0. I'll have to see if this is true. Glew 1.9.0 supports openGL 4.3. I've already built Celestia several times with Glew 1.9.
I've also been looking into the API for openGl 4.0. I need to study this further but at first glance, it seems that there is a lot that that can be done differently and maybe it will be an improvement.
If it seems worth while, I'll post a patch.
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