I’m making a raytracer following this article.
There is a code of checking for ray-sphere intersection (page #11)
Could you explain next things:
dot((p - c) ,(p - c)) = R*R. What does
dot(a, a), i.e. between the same vectors do? So, if they’re the same vectors, then angle between them will be always 0 and
cos(theta)will be always 1 and
dot(a, a)will give squared length of vector
- I don’t understand how he’d made a quadratic equation at all