1) f(x) is linear if f(x)=(-a2/a1)x-b, and later
2) f(x) is linear if f(x1+x2)=f(x1)+f(x2)
But the function f(x)=x+1 is linear according to (1), but not according to (2). And there is no mention of affine functions, so it's not immediately clear why the same word is used to mean different things.
(The APIs don’t let you use the actual environment for reflections, right?)
| (The APIs don’t let you use the actual environment for reflections, right?) That's a good point..I don't know the answer to your question but maybe I just need to add a light source in the virtual world.