Calculating rotation along a path

Question

I am trying to animate an object, let\'s say its a car. I want it go from point

x1,y1,z1

to point x2,y2,z2 . It moves to those points, but

Answer 1

Always pointing the car toward the destination point is simple and cheap, but it won't work if the car is following a curved path. In which case you need to point the car along the tangent line at its current location (see other answers, above).