[InOneWeekend] Total Internal Reflection Confusion

[code-monkey-101]

First of all, thank you for this great book series.

I'm confused about chapter 10.3 of book 1, though. In chapter 10.2 Snell's Law is introduced. Chapter 10.3 "fixes" total internal reflection:

Why does this not look right? The result at the end of chapter 10.3 looks like this:

If you hadn't changed the materials in chapter 10.3, there would be no difference to the result of chapter 10.2. Also, I downloaded your source code and put a break point in the "cannot_refract" line which doesn't trigger.

Total internal reflection is definitely something that can happen but I don't think we are running into this issue here.