[osg-users] Multiple Node Intersection

[Andrew Cunningham]

Hi ,
Maybe you figured it out by now, but you are only looking at the
"first intersection" of the picker ( getFirstIntersection). You need
to iterate over all intersections.

Andrew

On Fri, Dec 18, 2020 at 9:15 AM marco.... at elmansrl.eu
<marco.maisano at elmansrl.eu> wrote:
>
> Hi,
>
> I need to make the selection (pick) of a node, going to check if that node is present within an area built around the mouse click point.
>
> This should mean that, if there are more nodes inside that area, the pick event returns them to me.
>
> Currently for the point selection, therefore of a single node in a specific x and y, I successfully use osgUtil :: LineSegmentIntersector.
>
> Studying on the OSG book, I read that selection existed by checking inside a box, implemented by osgUtil :: PolytopeIntersector.
>
> Below I propose part of the code,
>
> double w(200), h(200);
> osgUtil::PolytopeIntersector* picker = new osgUtil::PolytopeIntersector(osgUtil::Intersector::CoordinateFrame::WINDOW, x - w, y - h, x + w, y + h);
> osgUtil::IntersectionVisitor iv(picker);
> viewer->getCamera()->accept(iv);
> if (picker->containsIntersections())
> {
> const osg::NodePath& nodePath = picker->getFirstIntersection().nodePath;
> auto intersections = picker->getIntersections();
> if (intersections.size() != 0) {
> auto hitr = intersections.begin();
> if (hitr->nodePath.size() != 0) {
> for (int i = 0; i < hitr->nodePath.size(); i++) {
> if (systemTargetMap[hitr->nodePath.at(i)->getName()]) {
>       cout << "Node Name: " << systemTargetMap[hitr->nodePath.at(i)->getName()] << endl;
> }
> }
> }
> }}
>
> Unfortunately, this selection only returns me one node, even if there are two (or more) very close together.
>
> What am I doing wrong?
>
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