locking on target

Question

I'm having problem with locking one object on another. Lets image an turret which always targets flying plane. I come to this solution:

1. Compute yaw = atan2(z2-z1, x2-x1)
2. Compute pitch = atan2(y2-y1, z2-z1)
3. Rotate

What do you think about such method? Is there any "faster" way without using atan2? Can I achieve same effect with just quaternions operations?

Answer 1

To get an object A to point towards a point B, then it's not difficult.

Vector current_heading = non_rotated_heading_of_object * object->rotation;
Vector target_heading = (target_position - object->position).normalize();
Vector axis = current_heading.cross(target_heading);
float angle = std::acos(current_heading.dot(target_heading));
Quaternion rotation = rotateAngleAxis(axis, angle);