Intersections and transparent geometry

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From: Simon C Mills (simon++at++wgs.estec.esa.nl)
Date: 01/19/2001 06:35:17

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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