Transform: tranlation and rotate confusion! 
Author Message
 Transform: tranlation and rotate confusion!

I am very confused about the options under the Transform node. Can
anyone help (or point me to a resource that explains them properly?)

In more detail:

I don't understand what the "center" does (for me, nothing). What I want
to do is transform the local origin of a child to a global point in
space, and then rotate about a vector in that new coordinate system, and
optionally translate along one of the new axes.

What I seem to be finding is that the "center" does nothing, and the
"rotate" is about a vector defined in the global system.

Looking forward to learning something

Thanks in advance

Ron


would reach me faster and I'd be very happy!

  cresswell.vcf
< 1K Download


Sat, 02 Nov 2002 03:00:00 GMT  
 Transform: tranlation and rotate confusion!

I believe this is accurate, and I don't think I could explain it better.

http://www.best.com/~rikk/Book/ch3-352.htm

-Rex

Quote:

> I am very confused about the options under the Transform node. Can
> anyone help (or point me to a resource that explains them properly?)

> In more detail:

> I don't understand what the "center" does (for me, nothing). What I want
> to do is transform the local origin of a child to a global point in
> space, and then rotate about a vector in that new coordinate system, and
> optionally translate along one of the new axes.

> What I seem to be finding is that the "center" does nothing, and the
> "rotate" is about a vector defined in the global system.

> Looking forward to learning something

> Thanks in advance

> Ron


> would reach me faster and I'd be very happy!



Sat, 02 Nov 2002 03:00:00 GMT  
 Transform: tranlation and rotate confusion!

Quote:

> I don't understand what the "center" does (for me, nothing). What I want
> to do is transform the local origin of a child to a global point in
> space, and then rotate about a vector in that new coordinate system, and
> optionally translate along one of the new axes.

> What I seem to be finding is that the "center" does nothing, and the
> "rotate" is about a vector defined in the global system.

I've made great use of this in creating satellites which orbit in
circular orbits around planets (in IrishSpace) - the trick is to set the
center as an offset from the object's center (for instance 0 0 -30), and
also translate the object in the opposite direction (0 0 30). Now this
transform will rotate around what used to be the center (0 0 0), if you
ROUTE the output from an Interpolator to the Rotation.

I can't put my head around exactly what you're trying, but Rex's
reference to the Online vrml 97 Manual should give you what you need.

- Paul



Sat, 02 Nov 2002 03:00:00 GMT  
 Transform: tranlation and rotate confusion!
this online VRML manual you refer to is merely the ISO VRML 97
specification, a proper version (in HTML, pdf, or my favourite, windows help
format) is available at www.vrml.org
db


Quote:

> > I don't understand what the "center" does (for me, nothing). What I want
> > to do is transform the local origin of a child to a global point in
> > space, and then rotate about a vector in that new coordinate system, and
> > optionally translate along one of the new axes.

> > What I seem to be finding is that the "center" does nothing, and the
> > "rotate" is about a vector defined in the global system.

> I've made great use of this in creating satellites which orbit in
> circular orbits around planets (in IrishSpace) - the trick is to set the
> center as an offset from the object's center (for instance 0 0 -30), and
> also translate the object in the opposite direction (0 0 30). Now this
> transform will rotate around what used to be the center (0 0 0), if you
> ROUTE the output from an Interpolator to the Rotation.

> I can't put my head around exactly what you're trying, but Rex's
> reference to the Online VRML 97 Manual should give you what you need.

> - Paul



Sun, 03 Nov 2002 03:00:00 GMT  
 Transform: tranlation and rotate confusion!

The annotations are what make "The Annotated VRML 2.0 Reference Manual" just a
little more interesting :-) The examples and insights given by the authors (
Carey & Bell ) add quite a bit of value.

But you are correct, a lot of the content is straight from the spec.

-Rex

Quote:

> this online VRML manual you refer to is merely the ISO VRML 97
> specification, a proper version (in HTML, pdf, or my favourite, windows help
> format) is available at www.vrml.org
> db



> > > I don't understand what the "center" does (for me, nothing). What I want
> > > to do is transform the local origin of a child to a global point in
> > > space, and then rotate about a vector in that new coordinate system, and
> > > optionally translate along one of the new axes.

> > > What I seem to be finding is that the "center" does nothing, and the
> > > "rotate" is about a vector defined in the global system.

> > I've made great use of this in creating satellites which orbit in
> > circular orbits around planets (in IrishSpace) - the trick is to set the
> > center as an offset from the object's center (for instance 0 0 -30), and
> > also translate the object in the opposite direction (0 0 30). Now this
> > transform will rotate around what used to be the center (0 0 0), if you
> > ROUTE the output from an Interpolator to the Rotation.

> > I can't put my head around exactly what you're trying, but Rex's
> > reference to the Online VRML 97 Manual should give you what you need.

> > - Paul



Sun, 03 Nov 2002 03:00:00 GMT  
 
 [ 5 post ] 

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