coffee-splash scene

[wahn]

The coffee-splash scene from here:

https://www.pbrt.org/scenes-v3.html

Renders like this for C++ (using just 8 pixelsamples):

The Rust version looks like this:

Figure out why the coffee material does not pick up the brownish color ...

[wahn]

Commit eef3358 resolves the issue:

There is still a difference in the handle of the cup, but the main problem is solved. Closing the issue.