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Message-ID:  <37827E91.2326AB25@usc.edu>
Date:         Tue, 6 Jul 1999 15:09:21 -0700
Reply-To: Discussion list for Java 3D API <JAVA3D-INTEREST@JAVA.SUN.COM>
Sender: Discussion list for Java 3D API <JAVA3D-INTEREST@JAVA.SUN.COM>
From: Andrew n marshall <amarshal@USC.EDU>
Subject:      [JAVA3D] Transfrom3D.lookAt()
To: JAVA3D-INTEREST@JAVA.SUN.COM

I have a avatar that needs to be able to look at other objects in the
scene I imported from the VRML97 loader.  I've been trying to use the
Transform3D.lookAt() method, but I've been getting lots of bad results.
According to these messages:
  http://www.javasoft.com/products/java-media/mail-archive/3D/0280.html
  http://www.javasoft.com/products/java-media/mail-archive/3D/1472.html
...the lookAt method is really that buggy.

However, this message:
  http://www.javasoft.com/products/java-media/mail-archive/3D/1495.html
...suggests that I could invert the transform to get it to work.  I
tried it, but I got a transform that was almost correct, but faced the
wrong direction (PI around the y-axis).

If the need for the inversion was intentional, can someone explain the
design decision to me.  It doesn't make sense to me since, unlike
OpenGL, the world is not centered on the camera, so all uses of the
lookAt() method (cameras and external avatars) would need to be
inverted.


Thanks.


Anm

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