Simplex Noise

Ported from: https://github.com/ashima/webgl-noise/blob/master/src/noise2D.glsl

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Live demo

The noise function is imported, but we then need to set up a proxy function. This is because the macro system relies on inlining, and we want to create a function definition, not just inline the noise code at the point of use.

inline def fragment =
  Shader[FragmentEnv] { env =>
    import ultraviolet.noise.*

    def proxy: vec2 => Float =
      pt => simplex(pt)

    def fragment(color: vec4): vec4 =
      val n = (proxy(env.UV) * 0.25f) +
        (proxy(env.UV * 2.0f) * 0.25f) +
        (proxy(env.UV * 8.0f) * 0.25f) +
        (proxy(env.UV * 32.0f) * 0.25f)

      vec4(vec3(n), 1.0f)
  }