Andrew,
This may not answer your question directly,but it may help.
The following is a code snippet (courtesy of Thomas Auinger)
which sets the viewplatform looking at the origin while rotating
in a circle.It inverts the transform just before applying it to the view
object.
----------------------------------------------------------------------------
-----------
Transform3D.lookAt(Point3d eye,
Point3d center,
Vector3d up)
is fine. Just remember, to INVERT the transform before
assigning it to the TransformGroup, that holds your ViewPlatform.
Following is a code snipplet I use to have the camera move in
a circle while always looking the the circle center:
public void calcViewpoint()
{ Transform3D viewpoint = new Transform3D();
// 'angle' describes the current position on the circle
// while 'distance' is the circle's radius.
double eyeX = Math.cos(angle) * distance,
eyeZ = Math.sin(angle) * distance;
Point3d eyeLocation = new Point3d(eyeX, 0.0d, eyeZ);
Point3d lookingAt = new Point3d(0.0d, 0.0d, 0.0d);
Vector3d up = new Vector3d(0.0d, 1.0d, 0.0d);
viewpoint.lookAt(eyeLocation, lookingAt, up);
viewpoint.invert();
viewTransformGroup.setTransform(viewpoint);
}
----------------------------------------------------------------------------
---------------
It works fine.
Hope this helps a bit.
Daryle.
-----Original Message-----
From: Andrew n marshall <[EMAIL PROTECTED]>
To: [EMAIL PROTECTED] <[EMAIL PROTECTED]>
Date: Wednesday, July 07, 1999 9:17 AM
Subject: [JAVA3D] Transfrom3D.lookAt()
>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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