Hi Dave,
Thanks for your help... however could you be a little more
specific on the methods or combination of methods from the Transform3D
object that can be used to extract a radian value for rotation. I have the
JavaDoc for Transform3D and I can get the rotationScale matrix of the
Transform, but I'm unsure how to extract a radian value out of that matrix.
cheers,
Quoc.
At 07:52 AM 13/06/2001 -0400, you wrote:
>Heh, it's funny that the internet has spawned all sorts of unspoken social
>norms. For example ALL CAPTITAL letters is shouting, and multiple ?? markes
>generally means a rising inflection on the last syllable with a slight
>increase in the volume of the tone. Three and four ???? mean a slightly
>hysterical edge to the question and often is used to issue a incredulous
>declaration like "you say this, how can this be????" This is because you
>know the person had to type out four ? and you can picture them hitting the
>keys pound-pound-pound-pound while they grit their teeth.
>
>Now that my morning social observation has probably irritated a few people
>let me answer the question at hand.
>
>Once you have the transformation from the view platform you can get just the
>rotation component of the matrix using methods in the Transform3D. This
>will be in radians. Just note that it is a rotation from the (0,0,-1)
>direction in a clockwise direction. Personally if I was solving the problem
>I would extract the rotation component from the view and put it in a new
>transformation, build the "arrow" geometry pointing in (0,0,1) and transform
>it using the rotation.
>
>Dave Yazel
>
>-----Original Message-----
>From: Quoc Huynh [mailto:[EMAIL PROTECTED]]
>Sent: Wednesday, June 13, 2001 6:35 AM
>To: [EMAIL PROTECTED]
>Subject: Re: [JAVA3D] View Platform FOV Direction
>
>
>Hi Paul,
>
> okay, i've got the transform and u suggest transforming the
>vector(0,0,-1) to work out how this vector maps in 3D space. From the new
>vector, I can find angle between the two vectors, and hence find the angle
>of rotation about the y axis. Is this correct???. Is this the only way to
>extract the rotation angle?? or is there a simpler method. I would just
>like to find the angle of rotation in radians. by default the rotation
>value is set at 0 (looking down the Z axis) and PI/2 is look looking
>parallel to the X axis. I just need to find that theta value for rotation.
>
>
>cheers,
>
>
>Quoc.
>
>
>At 08:51 AM 13/06/2001 +0200, you wrote:
> >use the Viewplatform . getLocalToVworldTransform( ) method and transform
> >e.g. the
> >vector (0,0,-1) the you get a vector you are looking for in 3d space. Set
> >Capability
> >bits to read the above mentioned transformation.
> >
> >regards
> >Paul
> >
> >Quoc Huynh schrieb:
> >
> > > Hi all,
> > >
> > > I'm trying to retrieve a value from the viewing platform that
> > will tell me
> > > in which direction the viewing platform is looking. I have a viewing
> > > platform moving through a terrain, the position of the viewing platform
>is
> > > mapped to a 2D image of the terrain, updated with the translation
>component
> > > of the viewing platform to show its position. Ideally i would like to
>have
> > > an arrow on the 2D map showing, the direction of the field of view in
>the
> > > current 3D terrain.
> > >
> > > Does anyone know how to retrieve this information????
> > >
> > > cheers,
> > >
> > > Quoc.
> > >
> > >
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