Vivek:
The reason the Java3D implementation does not use display list for
by-ref geometry is because OpenGL display list memory is retained from one
call to another. When a Java3D app uses geometry by-reference the Java3D
implementation internally trades off performance for space. In future, we
hope to add an API that gives user the control on this Space Vs
Performance tradeoff.
-Uma
Java3D Team
> MIME-Version: 1.0
> Date: Tue, 17 Oct 2000 14:36:39 -0700
> From: Vivek Verma <[EMAIL PROTECTED]>
> Subject: Re: [JAVA3D] Geometry By-Ref vs. Copying question
> To: [EMAIL PROTECTED]
>
> That sounds a bit disappointing. The reference changes or updating of
data associated with the references is recommended via the UpdateGeometry
interface so it should be possible to use display lists in OpenGL. A user
can call updateData() in the class GeometryArray whenever they want to
update the geometry/color/normals etc so can't the display list be updated
at that time. Am I missing something here?
>
> Does sun have any plans to change this in the future?
>
> thanks,
>
> -vivek
>
> -----Original Message-----
> From: Kelvin Chung [mailto:[EMAIL PROTECTED]]
> Sent: Monday, October 16, 2000 5:21 PM
> To: [EMAIL PROTECTED]
> Subject: Re: [JAVA3D] Geometry By-Ref vs. Copying question
>
>
> >My question is this;
> >Is there any performance cost with the by-ref vs. copying in general,
> >meaning just regular rendering without GeometryUpdaters?
>
> Yes, using geometry by reference will prevent
> Display list (OpenGL) / VertexBuffer (D3D) being used
> (since the reference may change frequently).
>
> Under the new v1.2.1beta1 D3D, use of vertex buffer can
> significantly improve performance.
> Thanks.
>
> - Kelvin
> --------------
> Java 3D Team
> Sun Microsystems Inc.
>
>
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