Hi,
The problem turned out to be the definition of CONGRUENT
transformation... (which all world-to-view transformation have to be)
My y-flip matrix is only (AFFINE | NEGATIVE_DETERMINANT), even though J3D
docs say that matrix is a CONGRUENT transformation if it is:
"an angle- and length-preserving matrix, meaning that it can
translate, rotate, and *reflect* about an axis, and scale by an amount
that is uniform in all directions"
I don't know the exact definition of CONGRUENT, but it seems that J3D
makes a classification error not setting the CONGRUENT bit for my y-flip
transformation?
Which is, BTW:
1 0 0 0
0 -1 0 0
0 0 1 0
0 0 0 1
Any mathematicians out there?
-- Matti
>Hi Matti,
>
>At 20:00 14.08.00 , you wrote:
>> For some reason I get only blank image in compatibility mode if I try to
>>reflect (mirror) y-axis like this:
>>
>> // relevant View setup code
>> tf = new Transform3D();
>> tf.setScale(new Vector3d(1,-1,1));
>> view.setVpcToEc(tf);
>
>OK, since nobody else has been able to help so far, I'll take a stab at it.
>My guess is that your view already HAS a Transform set up, which your
>setVpcToEc is replacing completely, with some of the previous magic
>gone.
>
>What I would try in your place is to get a hold of the original Transform3D
>using View.getViewPlatform().getTransform()
>(or something like that, I'm quoting from a leaky memory), which will give
>you an array of Transform3Ds (usually only one) which you can then use
>as the basis for your new Transform.
>
>I hope this is enough to give you a start. 3D geometry hurts my head so
>I'm not willing to go deeper into detail :)
>
>-Carl-
>
>===========================================================================
>To unsubscribe, send email to [EMAIL PROTECTED] and include in the body
>of the message "signoff JAVA3D-INTEREST". For general help, send email to
>[EMAIL PROTECTED] and include in the body of the message "help".
>
===========================================================================
To unsubscribe, send email to [EMAIL PROTECTED] and include in the body
of the message "signoff JAVA3D-INTEREST". For general help, send email to
[EMAIL PROTECTED] and include in the body of the message "help".
