Hi Carsten,
thanks for your answer. I'm trying your piece of code right now, but somehow I
can't find the
osg::GeoPnt3fPropertyRefPtr as well as the osg::GeoPnt3fProperty function.
Are these OpenSG 2.0 features only?
Unfortunately I have to use the 1.8 version. Is there a usable equivalent?
Maybe the GeoPositions3fPtr?
thanks, greets Andy
--- Carsten Neumann <carsten_neum...@gmx.net> schrieb am Mi, 21.7.2010:
Von: Carsten Neumann <carsten_neum...@gmx.net>
Betreff: Re: [Opensg-users] Copy triangles into a new geometry
An: opensg-users@lists.sourceforge.net
Datum: Mittwoch, 21. Juli, 2010 14:27 Uhr
Hello Andy,
Andy Bartz wrote:
> I have a virtual model consisting of different .obj gometries using
> openSG. I already managed to find out the hit triangle Index and it's
> related obj Object, by clicking in my virtual scene.
>
> What I'm trying to do is let the user select a number of connected
> triangles of one .obj Object. After that I want to create a new geometry
> object consisting only of the selected triangles, without changing the
> original geometry.
the triangle index from the IntersectAction can be used together with a
TriangleIterator to get all relevant properties of the triangle
(positions, normals, colors, texcoords, ...).
> Therefore I kind of need to "copy" the selected triangles somehow.
since the TriangleIterator gives you access to all the information about
the triangles you can create a new Geometry and add the needed
positions, normals, etc. to it.
> Is there an easy way to achieve that?
hm, there is no helper function to make partial copies of geometry in
the way you need it - such a use case has not come up yet. The basic
steps would look somewhat like this:
// triIdx is the triangle index from the IntersectAction
TriangleIterator triIt = geo->beginTriangles();
triIt.seek(triIdx);
// triIt 'points' at the hit triangle
GeometryRefPtr geoCopy = Geometry::create();
GeoPnt3fPropertyRefPtr pnts = GeoPnt3fProperty::create();
pnts->addValue(triIt.getPosition(0));
pnts->addValue(triIt.getPosition(1));
pnts->addValue(triIt.getPosition(2));
// similar for normals, etc.
// you also need to set lengths and types on the geometry (please see
// the tutorial <http://www.opensg.org/wiki/Tutorial/OpenSG2/Geometry>
// for details on the geometries workings).
// add the new geometry to the scene graph
NodeRefPtr geoCopyN = makeNodeFor(geoCopy);
rootNode->addChild(geoCopyN);
Cheers,
Carsten
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