I read this yesterday, with the two responses and want to make sure I
understand the situation. You have a mesh which currently is rendered in
the x,z plane with the normals pointing in a generally upward (positive Y)
vector? And you want to turn this upside down? Why not just rotate it?
The transform will transform the normals as well as the verticies. If you
did this, then viewed from the bottom the surface would appear the same as
it did from the top.
BUT if you mean you want to flip it over and view the "backside" of the
surface from the top, then you would have to reverse the normals.
I want to make sure there is no implication that you cannot flip and object
without manually changing the normals.
Dave Yazel
> ----------
> From: Yan Laporte[SMTP:[EMAIL PROTECTED]]
> Reply To: Discussion list for Java 3D API
> Sent: Tuesday, August 15, 2000 1:37 PM
> To: [EMAIL PROTECTED]
> Subject: [JAVA3D] flipping geometry
>
> Hello everyone...
>
> I was wondering if anyone has found a way to flip an object using J3D...
>
> The geometry is just a triangle array that I create from a indexed
> trinagle
> set from a VRML file (home made loader), I read the normals from ths file
> as
> well... I would like to just flip that object over the x coordinate. As
> far as flipping the geometry it seems to work fine by the just switching
> the
> sign on th ex coordinate of each points... However there is a problem
> with
> the normals... I can't figure out how to have the normals follow. If
> leave
> them as is of course it is a problem because they are facing the wrong
> way... I try to change the sign of the x coordinates on the normal vector
> as well (something that made sense to me) and it seems to be working only
> partialy. Using negative scaling factors doesn't seem to do the trick
> either.
>
> Does anyone has ever flipped an object in J3D or found a way ti achieve
> similar results. Maybe I am just poor at linear algebra.
>
> Could that be a new transform made available in the next verosin of J3D as
> well?
>
> Yan Laporte
> DMI
> Universit� de Sherbrooke
> [EMAIL PROTECTED]
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