For my raytracing needs, I'd like to find a way to compute a normal from a given 3d equation. This equation can be either a parametric one or a cartesian one (preferably in canonical form).
From my researches on the internet, it seems to be doable by computing the gradient of the equation but I want to be sure about that.
I manually tried to test against the sphere cartesian equation and it worked but that's not enough to prove that that is the solution.