“Progress is made by lazy men looking for easier ways to do things.” - Robert A. Heinlein
I hacked in a quick lighting effect for the planet atmosphere from space tonight.
It looks kinda OK in that shot (and is almost free to render), but it’s a fairly rubbish implementation. What I really need to do is implement Rayleigh scattering like in this article. That’d look a lot better, and would actually be somewhat accurate.
Today I started trying to improve the appearance of the planet from space. The biggest problem so far with the space scene is that the textures will degrade with the vertex complexity - so when you view the planet from far away, the textures look bad, due to the LOD being low. I now generate a 1024^2 texture at runtime that I use to texture the planet beyond a certain threshold. When you get closer, the higher detail texturing is blended in, until the ‘base’ texture is gone. This means that I have a much more detailed look from space.
Here’s a couple pictures of the method, with the atmosphere toggled. It still doesn’t look very realistic compared to some implementations, but I think it’s just a matter of getting some better colours, non-fake cloud effects, and atmospheric glow. It looks better than the old version already, though.
After reading some interesting stuff on how the Flight Simulator people did their cloud rendering, I decided to try my hand at it as well.
They’re not much more than a quick hack at the moment, but the results aren’t too bad. The biggest problem is the shading - it isn’t smooth, so you can make out the individual particles. That’s a result of the particles rotating to face the camera. I should update the particles in real time with their proper colours, which would fix that. I’m not sure if I’ll bother though 
The next step is to implement a render-to-texture based imposter system that will let me scale this planet-wide. This isn’t quite as simple as the Flight Simulator people made it out to be though, as I have to deal with three dimensions of imposters (due to the whole space flight thing). I’ll probably end up having two levels of imposters - one on a sphere that encompasses the whole planet which is faded out when you get below a certain altitude, and one on a cylinder that is used when you’re near the surface.
I found another couple of neat pics from today. Enjoy.
I recently re-enabled spherical planets again, and spent a few days fixing the myriad of issues that cropped up. It’s finally looking a little less broken, so I took some screenshots of a transition from ground to space
Tomorrow I’ll be looking at better atmosphere effects, and perhaps some clouds.
