From: Brian Furtaw (brian++at++sgi.com)
Date: 01/19/2001 07:03:31
Could you give some more information about what you are trying to do. If
you have doorways or windows in buildings that are modeled transparently
it will require a different solution then trying to shoot through trees.
What are you intersecting with and why? In Performer each pfNode carries
an isect mask so you can have classes of objects that behave differently
in isect queries. You are most likely going to need to add some extra
information to the scenegraph to solve your problem.
Brian
Simon C Mills wrote:
>
> Hi all,
>
> I'm doing intersection testing on my scene with pfNode::isect. The
> problem comes when I'm intersecting with geometry modelled with
> transparent areas in the textures (.inta and .rgba textures). Quite
> correctly, the intersection test returns true for these polygons even
> though some parts are transparent and _visually_ produces incorrect
> results. Unfortunately my models use this modelling technique
> extensively so it is quite disturbing.
>
> What I need is an additional check that takes into account the
> transparency of the polygon at the point of intersection with the pfSeg.
> Although this may just be possible I guess it could be slow.
> Alternatively, maybe it's possible to have a seperate high-resolution
> model just for intersection testing that does not use transparent
> textures. That would be quite an overhead to maintain and load at
> run-time so is not ideal.
>
> So, has anybody faced this problem before and got a workable solution
> they would be willing to share? Failing that does anybody have any good
> ideas to get around this problem?
>
> Many thanks, Simon
> _______________________________________________________________________
>
> Simon Mills
> Silicon Worlds S.A.
> c/o Modelling & Simulation Section (TOS-EMM) Tel: +31 (0)71 565 3725
> European Space Agency (ESA/ESTEC) Fax: +31 (0)71 565 5419
> Postbus 299, 2200AG Noordwijk e-mail: simon++at++wgs.estec.esa.nl
> The Netherlands http://www.estec.esa.nl/wmwww/EMM
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