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A standalone atmosphere shader for SHADERed and shadertoy (https://www.shadertoy.com/view/wlBXWK)

This repo is meant as a way to research and explain a (somewhat simple) atmospheric scattering implementation

Roadmap:

• chapman function for approximate optical depth
• better overall integrator (partly done already)
• planet shadow
• multiple scattering

A good approximation can be found here:https://zero-radiance.github.io/post/analytic-media/However, it would be nice to keep this function simple, without any erfc, and sqrt, which could result in a fully analytical atmospherehttps://www.shadertoy.com/view/4lVGRy uses a manual fit to the IE table for precomputed scattering, which might work good enough for thisThis:https://www.shadertoy.com/view/XlBfRD renders the atmosphere back to frontWhat does this allow? alpha blending, effectively you calculate scattering for a segment, then blend it with all segments behind each otherThis reduces an exp(-x) you have to put the entire segment scattering into, some other form of order-independant transparency could also work

Space glider (https://www.shadertoy.com/view/MdGfDG) big shader, can be slow to loadalready does this, by using the delta-eddington stuffidk how this works, but it's effectively adding the rayleigh color to the unshadowed part of the atmoIt's kinda hacky but it works

If the above works and a fully analytical atmo is possible, it might be possible to integrate it over an angle, and get multiple scattering from there