# Oren-Nayar Reflectance

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:

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

Thank you!

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