It’s day time, the sun is up, it’s a cloudless day. Ambient light is bouncing all over, including into a south facing window (i.e. no direct sunlight.) How does the Eye Light Emitter do its job in this case?

Now, I don’t mean “this concept is impossible” because that’s clear. I’m genuinely curious how this would have been explained by someone at the time.

https://www.scratchapixel.com/lessons/3d-basic-rendering/int...

In the real world light travels from the light source to the eye. But this lesson xplains that simulating this with a computer is not efficient. A more efficient technique is to follow the path of light but in reverse, starting from the eye and waking back to the lights making up the scene. Again read the lesson(s) it's all explained and that's why the lessons are there in the first place.