Rotating Objects Using Quaternions

Summary:

This article discusses the use of quaternions from the practical stand
point of including smoothly interpolated rotations in modern 3D games. It
also gives an overview of some other forms of rotation representation as
well as presenting information on SLERP and useful code fragments.

Problem:

The author is specifically discussing how game developers can include
smoothly interpolated rotations in their real time 3D rendered games.

Method:

The article covers several forms of rotational representation and how to
convert to and from quaternions. Special focus is given to the rotational
matrix form as it is needed by most graphics systems. The author takes the
interesting strategy of talking the reader through the mathematics of
quaternions as well as presenting actual coded implementations. The author
also focuses on the SLERP formula and how it can be implemented.

Key Ideas:

Quaternions can provide an unambiguous representation of rotations as well
as allowing for smooth interpolation between rotations. However
quaternions are expensive to work with in a real time system and are best
reserved for rotations which must be very smoothly interpolated in order
to not interfere with user perception of the game.

Contributions:

This paper did not present any new theories or ideas, but it explained the
existing ideas clearly and unambiguously as well as providing useful code
snippets.

Questions:

Considering that this article was written back in 1998, I wonder if
advances in hardware have made the "expensive" quaternion more appealing
to game programmers or if it is still considered a tool that should only
be used in very select cases.