[java3d] Transform3D problem?

[Ellery Chan]

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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