Tests if this Sphere is finite.
A sphere is finite if its members pos and r do not contain floating-point NaNs or +/-infs in them.
True if the members pos and r both have finite floating-point values.
pos, r, IsDegenerate(), IsFinite(), IsInf(), IsNan(), IsFinite(), inf, negInf, nan, float3::nan, float3::inf, SetNegativeInfinity().