At some point we were going to get past simple Blinn-Phong shading.

rt 4 implements reflection, refraction, Beer's law and Schlick's approximation so we can have transparent dielectric and conducting materials.

0.62s

A metal ball with reflectance <0.9 0.9 0.9> and a glass ball with η = 1.05. Note the reflection on the side of glass ball- an effect of Fresnel reflection.

2.80s

Two glass plates and a ball.

32.88s

Horse, cube and glass mug. Implementing a SAH on the BVH seemed to help here. Maximum recursion depth is 6 which enables up to 2⁶ auxiliary rays per camera ray.

4.13s

4.22s

Conductive killeroo models, first with reflectance 0.5, then with 1.

18.27s

Glass killeroo, interesting refraction patterns. η = 1.1.

Rendering times are on a i3-3217U.

Compiled with clang-5.0 on DragonFly BSD.