I'm trying to implement Oren-Nayar reflectance and I don't quite understand the Wikipedia article on it.

In the article, it has this diagram:

enter image description here

I can't figure out what $(\theta_i, \phi_i)$ and $(\theta_r, \phi_r)$ represent. They are used in the equation.

Thank you!

  • 3
    $\begingroup$ The spherical coordinate angles defining the direction towards the light, and towards the eye. $\endgroup$
    – lightxbulb
    Oct 5, 2019 at 21:35
  • $\begingroup$ @lightxbulb Ah, that makes sense, thanks! $\endgroup$
    – MCMastery
    Oct 6, 2019 at 3:50


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