Hi,
there is a picking mechanism included in OpenSG, which intersects a
ray with some geometry. The returned information include the Node that
was hit, the polygon within the node, the exact location on that
polygon, and so on. We have a method within our framework that looks
like this
void getObjectAt(int x, int y, OSG::NodePtr &node,
OSG::Pnt3f &hitPoint, OSG::Vec3f
&hitNormal,
OSG::Int32 &hitTriangleIndex)
{
Line line;
PerspectiveCameraPtr camera = scene->getCamera();
NodePtr root = scene->getObjectsRoot();
ViewportPtr vp = getViewport();
camera->calcViewRay(line, x, y, *vp);
IntersectAction *action = IntersectAction::create(line);
action->apply(root);
if (action->didHit())
{
// cerr << "SGQGLManagedWidgetP::selectObjectAt info: hit
something" << endl;
node = action->getHitObject();
hitPoint = action->getHitPoint();
hitNormal = action->getHitNormal();
hitTriangleIndex = action->getHitTriangle();
}
else
{
// cerr << "SGQGLManagedWidgetP::selectObjectAt info: hit
nothing" << endl;
node = NodePtr(0);
hitPoint = Pnt3f(0.0f, 0.0f, 0.0f);
hitNormal = Vec3f(0.0f, 1.0f, 0.0f);
hitTriangleIndex = 0;
}
delete action;
}
Maybe you want to look into the IntersectAction to see if there is
some other info you are interested in. I found that the normals are
not always computed the way I expected, so I wrote a little funtion
that computes the normal of the hitPoint based on the index of the hit
Polygon. If you need something like that, let me know.
Cheers,
Daniel
On 14/03/2008, Christoph John <[EMAIL PROTECTED]> wrote:
> Hello,
> I am quite new to opensg and I am searching for a way to obtain a polygon on
> which a user has clicked.
> Is there a kind of color picking or something similar already integrated
> into opensg and where do I find it?
> Thanks for your help
>
> Cheers
> Christoph
> --
> Psssst! Schon vom neuen GMX MultiMessenger gehört?
> Der kann`s mit allen: http://www.gmx.net/de/go/multimessenger
>
> -------------------------------------------------------------------------
> This SF.net email is sponsored by: Microsoft
> Defy all challenges. Microsoft(R) Visual Studio 2008.
> http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/
> _______________________________________________
> Opensg-users mailing list
> [email protected]
> https://lists.sourceforge.net/lists/listinfo/opensg-users
>
--
Daniel Wickeroth
Moltkestraße 88
50674 Köln
Home 0221 3569325
Work 0221 478 86502
Mobil 0176 700 40 252
-------------------------------------------------------------------------
This SF.net email is sponsored by: Microsoft
Defy all challenges. Microsoft(R) Visual Studio 2008.
http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/
_______________________________________________
Opensg-users mailing list
[email protected]
https://lists.sourceforge.net/lists/listinfo/opensg-users
