I tried to find some code that wasn't minified to assess the quality of this, and I found some shader code for the sky in the gemini version. The whole shader looks like it was regurgitated verbatim. This wouldn't hold up to licensing scrutiny. Here's a snippet from it:

  // wavelength of used primaries, according to preetham
  const vec3 lambda = vec3( 680E-9, 550E-9, 450E-9 );
  // this pre-calcuation replaces older TotalRayleigh(vec3 lambda) function:
  // (8.0 * pow(pi, 3.0) * pow(pow(n, 2.0) - 1.0, 2.0) * (6.0 + 3.0 * pn)) / (3.0 * N * pow(lambda, vec3(4.0)) * (6.0 - 7.0 * pn))

Who's Preetham? Probably one of the copyright holders on this code.