[osg-users] TriStripVisitor issue

Emmanuel Roche roche.emmanuel at gmail.com
Mon Nov 23 04:14:02 PST 2009


Actually, I also noticed that OSG v2.8.1 uses version 1.0 of the tristripper
library.

As I'm quite in an hurry, I think I will re-implement my own tristripvisitor
with the latest version of tristripper and check if this makes a difference.
Will let you know what's the result of this test.

But I believe this could really be a generic issue (it happens with all the
models I tested) and thus would mean many people are currently using "not so
well tri-stripped" geometries if they use this optimiser feature !  (it is
the case for instance in the OSGExp export plugin for 3DS max as I've
noticed this issue there for the first time).

regards,
Manu.



2009/11/23 Robert Osfield <robert.osfield at gmail.com>

> Hi Manu,
>
> If the tristripper doesn't connect the triangles together well then it
> can result on few tristrips and lots of unconnected traingles that it
> has to put into a single list of triangles to avoid lots of separate
> primitive calls.
>
> As to why your model is not being stripped well I can't say.  We've
> used 3rd party code to do the tri-stripping so I'm not best placed to
> answer the low level questions, but... the original author of the cdoe
> Tanguy Fautre is now an OSG user and I believe still on the list so
> perhaps he'll be able to chip in ;-)
>
> Robert.
>
> On Mon, Nov 23, 2009 at 11:08 AM, Emmanuel Roche
> <roche.emmanuel at gmail.com> wrote:
> > Hi everyone,
> >
> > I have a strange problem with the TryStripVisitor:
> >
> > When I use it on a model (with about 6000 triangles, described as
> TRIANGLES
> > [thus using 18000 vertices]) I get trip strip primitive sets indeed....
> BUT
> > actually I get a few TRIANGLE_STRIP primitive sets with 4 vertices in
> each,
> > and then a single big TRIANGLES primitive set with about 17950 vertices
> !!!!
> >
> > So, most of the model is just not stripped at all ! any idea what I could
> be
> > doing wrong ???
> >
> > Moreother, I've noticed that the geometry is then transformed as an
> indexed
> > geometry... correct me if I'm wrong but indexed geometries are slower
> that
> > simple vertices ordered arrays. If there a way to switch this or am I on
> my
> > own on this ?
> >
> > Regards,
> > Manu.
> >
> >
> >
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> >
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