Production Ready Atmosphere Rendering

This implements Unreal Engine's skybox in Unity from Sébastien Hillaire's paper.

Setup

• Unity version: 6000.3.8f1
• URP Version: 17.3.0

How to use

• The sample scene is already set so that the background is rendered using this method. No need to hit play.
• The main script is called AtmosphereRenderer.cs, there is a game object with the same name in the demo running it. It receives a scriptable object containing the parameters for the atmosphere.
• Attaching an AtmosphereParameters scriptable object to the renderer or changing the values of a currently attached one will automatically update.
• You can create new parameters by right clicking the project window and going Create -> Data -> Lighting -> AtmosphereParameters.

Missing Features and Issues

• This does not implement the aerial view LUT.
• Going off the planet's atmosphere radius breaks the rendering. This can be fixed by adjusting the raymarching to account for the camera being outside the planet.
• Only considers one light source.
• Tone mapping and gamma correction is being done before the LUT gets upscaled. This helped a bit in performance, but doing it at the fragment stage should yield better visuals.

References

• https://sebh.github.io/publications/egsr2020.pdf
• https://www.shadertoy.com/view/slSXRW# <- Special thanks to Andrew Helmer for sharing this.
• https://www.shadertoy.com/view/fd2fWc# <- Potential fix for Aerial view.