jwh wrote:
> So my question is: are there others who'd like to use homogeneous matrices
> or am I just too academic?

Homogeneous matrices are indeed a purely academic invention in computer
graphics courses used to show how "great" they are, while in reality they
just obfuscate the subject matter to impress the unsuspecting student. Poor
teachers and book authors usually need them, while in real life you
implement the code to take human-readable forms of transformations (aka
rotation, translation, scaling) and turn them into homogeneous matrices
once. Then you never need to know about them any more as their mathematical
properties are fairly simple (well, matrices in general are simple after
all) - it is only visualizing homogeneous matrices content's meaning in 3D
that is non-intuitive.

The major real benefit homogeneous matrices have in programming with 3D
graphics today is that they are 16 scalars in size. Hence they are easier to
handle by computers when addressing scalars and using SIMD units compared to
3x3 matrices (which in various cases would be sufficient despite some
undesirable properties). In short, homogeneous matrices are nice, but
dealing with computer graphics, one really does not need to know more about
them than that they are matrices with a few interesting properties.

	Thorsten

PS: If you want something really useless, there is of course always the
rendering equation. You can tell a poor instructor or professor at
university if they ask for the memorized rendering equation in an exam ;-)

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