Re: [osg-users] intersection with quad mesh: only 3 vertices returned

[Torben Dannhauer]

Hi all

Thanks for your feedback, that turns my vague idea into basic knowledge I can 
build on to learn more :)

I'll continue as soon I'm back from my trip.

Thank you!

Best regards,
Torben ( currently sitting in a peruvian long distance
bus with more comfort than many aircrafts - entertainment, ac, hot meal, wifi 
for free - for only 4$ each 100km :D )

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Re: [osg-users] intersection with quad mesh: only 3 vertices returned

[Tueller, Shayne R Civ USAF AFMC 519 SMXS/MXDEC]

Torben,

My guess is that the quads are geometrically represented by two
triangles with a shared edge. I believe the intersector is returning a
ray/triangle intersection so one (that is hit) of the two triangles that
make up the quad is being returned.

This probably doesn't solve your problem but it may explain why you're
getting only 3 vertexes on return...

-Shayne

-Original Message-
From: osg-users-boun...@lists.openscenegraph.org
[mailto:osg-users-boun...@lists.openscenegraph.org] On Behalf Of Torben
Dannhauer
Sent: Tuesday, August 02, 2011 12:39 PM
To: osg-users@lists.openscenegraph.org
Subject: [osg-users] intersection with quad mesh: only 3 vertices
returned

Hi,

I have a mesh of quads. If i intersect them, it hits the face and
returns me the results (osgUtil::LineSegmentIntersector::Intersection
result)

As I tried to access the indices I realized that it only returns 3
vertices.
( result.indexList.size() == 3 ) 
Is this a bug or do I miss something?
I would like to acces the 4 vertices of the quad to manipulate the
vertex I intersect next to.

Thank you!

Cheers,
Torben

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Re: [osg-users] intersection with quad mesh: only 3 vertices returned

[Torben Dannhauer]

Hi S2LR,

I thought QUAD is a OpenGL primitive. Your statement make sence to me. But then 
OSG hides the substitution by 2 triangles quite good, also in the wiremode of 
osgViewer the quads are displayed.

I thought (even when not to often used as triangles) that quads are natively 
supported and would work with intersections.

Cheers,
Torben

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