Hi Ellery,
You have discovered a bug in the Java 3D implementation. Thanks for
bringing it to our attention. Unfortunately, a fix for this will not
make our 1.1.2 release, which should be on the web soon.
--
Kevin Rushforth
Java 3D Team
Sun Microsystems
[EMAIL PROTECTED]
>From: "Ellery Chan" <[EMAIL PROTECTED]>
>Date: Sun, 30 May 1999 00:50:50 -0400
>
>I've been trying to use the lookAt() method of Transform3D, but when I
>retrieve the transformation matrix and restore it later, the
>transformation type flags don't seem to be getting computed correctly.
>I don't think they get set correctly after the lookAt() either. Am I
>misunderstanding the type flags, or is there something wrong here?
>
>Here's my little test app. Can anyone explain the observed behavior?
>
>
>//**********************************************************************
>*******
>// CLASS: T3DBugTest
>// This class tests for existence of a bug in Transform3D where the
>transform
>// type is not properly set when a matrix is used to initialize the
>// Transform3D node. The lookAt() transformation doesn't seem to
>update the
>// type flags correctly, and neither does setting the Transform3D from
>a
>// matrix.
>//
>// Generated output (JDK 1.2.1, J3D 1.1.1):
>// AFFINE|CONGRUENT|IDENTITY|ORTHOGONAL|RIGID|SCALE|
>// AFFINE|CONGRUENT|IDENTITY|ORTHOGONAL|RIGID|SCALE|
>// AFFINE|CONGRUENT|IDENTITY|ORTHOGONAL|RIGID|SCALE|
>// AFFINE|
>//
>//**********************************************************************
>*******
>import javax.media.j3d.Transform3D;
>import javax.vecmath.Matrix4d;
>import javax.vecmath.Point3d;
>import javax.vecmath.Quat4d;
>import javax.vecmath.Vector3d;
>
>public class T3DBugTest
>{
> public T3DBugTest ()
> {
> final Transform3D t1 = new Transform3D();
> final Transform3D t2 = new Transform3D();
> final Matrix4d mat = new Matrix4d();
>
> pType(t1); // AFFINE|CONGRUENT|IDENTITY|ORTHOGONAL|RIGID|SCALE
> t1.lookAt(new Point3d(50,20,50), new Point3d(0,0,0), new
>Vector3d(0,1,0));
> pType(t1); // AFFINE|CONGRUENT|IDENTITY|ORTHOGONAL|RIGID|SCALE
> // (Should be AFFINE|CONGRUENT|RIGID, I think)
> t1.get(mat);
>
> pType(t2); // AFFINE|CONGRUENT|IDENTITY|ORTHOGONAL|RIGID|SCALE
> t2.set(mat); // should recompute type from matrix
> pType(t2); // AFFINE (Should be whatever t1 was!)
> }
>
> public void pType (Transform3D t)
> {
> final int flags = t.getType();
> if ((flags & Transform3D.AFFINE) != 0)
>System.err.print("AFFINE|");
> if ((flags & Transform3D.CONGRUENT) != 0)
>System.err.print("CONGRUENT|");
> if ((flags & Transform3D.IDENTITY) != 0)
>System.err.print("IDENTITY|");
> if ((flags & Transform3D.NEGATIVE_DETERMINANT) != 0 )
>System.err.print("NEGATIVE_DETERMINANT|");
> if ((flags & Transform3D.ORTHOGONAL) != 0 )
>System.err.print("ORTHOGONAL|");
> if ((flags & Transform3D.RIGID) != 0) System.err.print("RIGID|");
> if ((flags & Transform3D.SCALE) != 0) System.err.print("SCALE|");
> if ((flags & Transform3D.TRANSLATION) != 0)
>System.err.print("TRANSLATION|");
> if ((flags & Transform3D.ZERO) != 0) System.err.print("ZERO|");
> System.err.println("");
> }
>
> public final static void main (String[] args)
> {
> new T3DBugTest();
> }
>}
>
>--
>Ellery Chan
>Harris Corp.
>[EMAIL PROTECTED]
>
>
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