Hi Mike,
thanks for your answer first. A position vector is a position expressed
in vector form. It=B4s just another term for me to describe a
3dimensional position (and it=B4s shorter to write "position vector"
than "position expressed in vector form in three dimensional space" ;)
As I said, I am not new to 3d math and graphics. I am developing
graphics software for about 6 years, so I am aware of the word
definitions inherited from the mathematical word "vector". Anyway,
thanks for the well-intented description. :-)
Anyway, could you answer my initial question? What happens to the
position stored in the SoTransform object when constructing the
rotation matrix (or quaternion, if that=B4s the internal structure a
SbRotation holds) with the described constructor?
That=B4s where my problem of comprehension is.
Thank you!!
Best
Samir
MikeHeck schrieb:
> info@[EMAIL PROTECTED]
wrote:
> > I have a SoTransform object. This holds a position vector (I have set
> > it with SetValue()).
> > Ok, now I have a direction vector: dV =3D (0,1,0.5);
> >
> > I recently saw somebody using this:
> >
> > transform->rotation.SetValue(SbRotation(SbVec3f(1,0,0),dV));
> >
> > ok, so I looked up what the SbRotation() Constructor that takes two
> > SbVec3f variables does. The reference says
> >
> > "the rotateFrom/To constructor defines rotation that rotates from one
> > vector into another."
> >
> > ok, I am not new to 3d math, but what does this mean? Let=B4s take the
> > example with dV I posted above. What happens to the position vector
> > stored in the SoTransform object by doing the above operation with dV?
> > What may be the result?
>
> What is a "position vector" ?
> Yes, the word vector has multiple meanings, but in 3D graphics you
> normally either have a position (a point in space) or you have a vector
> (a direction).
>
> This SbRotation constructor takes two vectors (two directions) and
> computes a rotation that rotates the first vector into the second
> vector. For example, you might use it to rotate a camera pointing in
> the first direction to be pointing in the second direction.
>=20
> -Mike
|
