I am learning how to do 3D development on android. I started with a simple rotating planet with some clouds. I have spent past 2 days trying to get atmospheric glow added to the planet. I looked online and tried working with shaders but was unable to get far.
My question is, what is the best way to achieve this? I nudge in the right direction may be all I need.
I attached a screenshot of the planet I have so far, as well as the end goal I am shooting for.
Thank you for any help.
Current progress:
End Goal:
http://25.media.tumblr.com/tumblr_m06q7l7BpO1qk01v6o1_500.png
What you need is usually done in post process render pass.So for example :
Pass -1 : Render the planet model into FBO texture attachment.
Pass- 2 :Set screen quad , and attach the texture from the previous pass as sampler uniform.
Then in the fragment shader apply a glow effect .
For the glow, there are many ways of doing it.For example you can draw the silhouette of the planet in the first pass ,give it color fill of your glow and then bluring it using smoothstep().Then in post -process pass you put it under the main planet texture.
In fact here you can see a lot of code samples on how to do a glow for circular objects.
One more thing.Adding blur based glow can impact the performance greatly on mobile device.There is a technique called “Distance Field”.Valve used it to anti-alias fonts.But it also can be used to do glow.You create a distance field texture texture copy of your planet silhouette once ,then in the post – process pass use it to do smooth glow effect.Fortunately for you there are functions to generate it .Here you can find the papers and the code how to get it done.