I am trying to find the surface normal of an ellipsoid, given a single xyz point on a surface. I am struggling to work out how to find the tangent of an ellipsoid. I couldnt find anything obvious on google, but I may have found a clue, and that is to somehow use a cone to calculate the tangent?
If I could work out how to find the tangent of the surface should easily be able to work out the normal vector on my own.
Are there any equations I should be aware of for calculating the tangent?
I have just had a thought, perhaps I need to take point p, and find the opposite point to work out where the clone intersects the two points? then where the two points meet, will provide me with a vector tangent to the original point?