From: Andy Little (andy_at_[hidden])
Date: 2006-06-12 10:03:23
"me22" <me22.ca_at_[hidden]> wrote in message
> On 6/11/06, Andy Little <andy_at_[hidden]> wrote:
>> OK. So going back to the original point. The intent in PQS is to use a
>> quaternion solely for representing a rotation in 3D space. Putting quaternion
>> a 3D namespace makes sense to me from that viewpoint and should help to
>> its intended purpose.
> In that case I think it should be called unit_quaternion to emphasise
> the point. It would also make it clear that the implementation is
> ensuring and assuming that w*w+x*x+y*y+z*z is very close to 1.
OK. This functionality will surely depend on the implementation of vect * quat ?
In boost::quaternion the quaternion seems to be normalised during the
calculation AFAICS. See <libs/math/quaternion/HS03.hpp>. I have to confess that
I don't know enough about quaternions to speak with authority. As Janek Kozicki
brought up yade http://yade.berlios.de/. My current plan is to look at that as
an example useage. Again only for rotations. I'm not even sure yet how I can
test the calculations on quaternions. I need to understand more about how they
are constructed, starting maybe from an [axis-vector,angle] type maybe, simply
because I can visualise that easier than 4 dimensions :-)
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