OOps, Re: Fixed text size query...

• To: Jim K <jimk@xxxxxxxxxx>, "'visad-list@xxxxxxxxxxxxx'" <visad-list@xxxxxxxxxxxxx>
• Subject: OOps, Re: Fixed text size query...
• From: Bill Hibbard <hibbard@xxxxxxxxxxxxxxxxx>
• Date: Wed, 12 Sep 2001 08:55:03 -0500

I wrote:

> 2. Since you know that:
> 
>   Transform3D theTransform = new Transform3D();
>   theTransform.set( 1 / aScale[ 0 ], theTranslationVector );
>   theTransformGroup_.setTransform( theTransform );
> 
> works for fixing the location and size, you might try:
> 
>   Transform3D theTransform = new Transform3D();
>   theTransform.set( 1 / aScale[ 0 ], theTranslationVector );
>   Transform3D scale = new Transform3D();
>   scale.set( 1 / aScale[ 0 ] );
>   theTransform.mul(scale);
>   theTransformGroup_.setTransform( theTransform );

Clearly this should not re-apply the scale, but apply the
inverse of the translation in 'scale'. That is:

  Transform3D theTransform = new Transform3D();
  theTransform.set( 1 / aScale[ 0 ], theTranslationVector );
  Transform3D translate = new Transform3D();
  Vector3d inverse = new Vector3d();
  inverse.x = -theTranslationVector.x;
  inverse.y = -theTranslationVector.y;
  inverse.z = -theTranslationVector.z;
  translate.set( inverse );
  theTransform.mul(translate);
  theTransformGroup_.setTransform( theTransform );

> I may have some detail wrong, like the order of multiplying
> matrices, but with a few experiments you may get it. When I
> write such transform matrix code, I always have to experiment
> to get it right.

And of course, you can probably accomplish the same thing
with your original code and experimenting with arithmetic
operations on the x, y and z values in theTranslationVector.

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

• Follow-Ups:
  • Re: OOps, Re: Fixed text size query...
    • From: Tom Rink

• References:
  • Fixed text size query...
    • From: Jim K
  • Re: Fixed text size query...
    • From: Bill Hibbard