Smooth cone normals

Question

I\'m trying to calculate smooth normals for a cone. In looking around for code samples and explanations, I consistently come across directions for face normals. I\'ve posted

Answer 1

At any point on the surface of a cone except the apex, there are two obvious kinds of tangent vectors: one tangent to the cross-sectional circle, or one up the slope. If you express the surface as a parametric equation with two parameters, you can get these tangent vectors as the two partial derivatives. Take the cross product of the tangents, and you get a normal vector. The order of the product determines whether the normal points inward or outward. Of course, the bottom face must be handled separately.