Re: Line prims vs. Wireframe state

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Rob Jenkins (robj++at++quid.csd.sgi.com)
Fri, 5 Dec 1997 21:09:23 -0800

On Dec 6, 1:15am, Ran Yakir wrote:
> Subject: Re: Line prims vs. Wireframe state
>
>
> Glenn Waldron wrote:
>
> > What's the performance difference, if any, between:
> >
> > a) a pfGeoSet with PFGS_LINE/LINE_STRIP primitives;
> > b) a pfGeoSet with solid prim type (e.g., PFGS_TRIS) using a
> > pfGeoState with PFSTATE_ENWIREFRAME enabled
> >
> > In other words, how does Performer handle the ENWIREFRAME state
> > flag? thanks- glenn.
> >
> >
>
> As far as I know, from looking at ogldebug traces, both modes will use
> GL_LINE_STRIP or GL_LINE_LOOP, so there shouldn't be a difference.I wonder
> why the ENWIREFRAME is not done with glPolygonMode (GL_LINES) ?
>

I think this is the case, it may be partially for 'historical' reasons: under
IrisGL not all platforms support polymode() although under OpenGL all platforms
should support glPolygonMode(GL_LINE) which would allow rendering of wireframe
as polygons ( less vertices down the pipe than lines ).

Cheers
Rob

-- 
________________________________________________________________
Rob Jenkins mailto:robj++at++sgi.com
Silicon Graphics, Mtn View, California, USA
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