Re: Coordinate System and eye

• To: Sylvain Fourny <sylvain.fourny@xxxxxxxxx>
• Subject: Re: Coordinate System and eye
• From: Bill Hibbard <hibbard@xxxxxxxxxxxxxxxxx>
• Date: Wed, 18 Apr 2001 06:47:54 -0500

Hi Sylvain,

> I want to use the z-buffer method to sort hidden and visible edges.
> For this, I need the position of the centered eye.
> I think that i must use the visad.java3d.DisplayRendererJ3D and found
> the appropriate transformation but unfortunately, there is not a lot of
> documentation on it...
> Can you explain me the difference between :
> - DisplayRendererJ3D.getTrans
> and
> - DisplayRendererJ3D.getViewTrans

In the Java3D documentation you'll see that the scene graph
has two parts: one for all the geometries to be displayed and
another to describe the geometry of the viewer. getTrans()
returns the TransformGroup above the geometries derived from
VisAD data objects, and getViewTrans() returns the
TransformGroup above the viewer. It is constructed in
UniverseBuilderJ3D.

> I try to applicate this transformations in both order but i still not
> found my viewPoint ?
> What is the View and can I use it ?
> Please help me, I'm completly lost in all this transformations...

Yes, 3-D transforms are generally tricky. I always have to
do lots of trial and error, and digging into code, to get
this kind of logic working. I'm afraid that's what you'll have
to do. I cannot give you easy answer unless I do the trial
and error and digging for you, and I'm too busy.

Good luck,
Bill
----------------------------------------------------------
Bill Hibbard, SSEC, 1225 W. Dayton St., Madison, WI  53706
hibbard@xxxxxxxxxxxxxxxxx  608-263-4427  fax: 608-263-6738
http://www.ssec.wisc.edu/~billh/vis.html

• References:
  • Coordinate System and eye
    • From: Sylvain Fourny
  • Re: Coordinate System and eye
    • From: Bill Hibbard
  • Re: Coordinate System and eye
    • From: Sylvain Fourny