[osg-users] How to pick the ShapDrawable in a HUD

GeeKer Wang wwthunan at gmail.com
Sat Apr 9 08:18:25 PDT 2016


Hi, all,

I noticed in osgpick.cpp that  osgText::Text and osg::Geometry could be
picked, but when I add an osg::Geode with osg::ShapeDrawable into the HUD
camera, the picking does not work anymore.

I list the code as follows. It will be appreciated if anyone can point out
where the problem is or provide the correct way.  Thanks in advance.

// g++ osgpick.cpp -Wall -O3 -W   -I/usr/include  -losgDB -losgGA
-losgViewer -losg -losgUtil -losgText -lOpenThreads  -losgWidget  -o
osgpick.out
#include <osgViewer/Viewer>

#include <osg/Geode>
#include <osg/MatrixTransform>
#include <osg/Camera>
#include <osg/io_utils>
#include <osg/ShapeDrawable>

#include <osgText/Text>

#include <sstream>

// class to handle events with a pick
class PickHandler : public osgGA::GUIEventHandler {
public:

    PickHandler(osgText::Text* updateText):
        _updateText(updateText) {}
    ~PickHandler() {}
    bool handle(const osgGA::GUIEventAdapter& ea,osgGA::GUIActionAdapter&
aa);
    virtual void pick(osgViewer::View* view, const osgGA::GUIEventAdapter&
ea);
    void setLabel(const std::string& name)
    {
        if (_updateText.get()) _updateText->setText(name);
    }
protected:
    osg::ref_ptr<osgText::Text>  _updateText;
};

bool PickHandler::handle(const osgGA::GUIEventAdapter&
ea,osgGA::GUIActionAdapter& aa)
{
    switch(ea.getEventType())
    {
        case(osgGA::GUIEventAdapter::PUSH):
        {
            osgViewer::View* view = dynamic_cast<osgViewer::View*>(&aa);
            if (view) pick(view,ea);
            return false;
        }
        case(osgGA::GUIEventAdapter::KEYDOWN):
        {
            if (ea.getKey()=='c')
            {
                osgViewer::View* view = dynamic_cast<osgViewer::View*>(&aa);
                osg::ref_ptr<osgGA::GUIEventAdapter> event = new
osgGA::GUIEventAdapter(ea);
                event->setX((ea.getXmin()+ea.getXmax())*0.5);
                event->setY((ea.getYmin()+ea.getYmax())*0.5);
                if (view) pick(view,*event);
            }
            return false;
        }
        default:
            return false;
    }
}

void PickHandler::pick(osgViewer::View* view, const osgGA::GUIEventAdapter&
ea)
{
    osgUtil::LineSegmentIntersector::Intersections intersections;

    std::string gdlist="";

    if (view->computeIntersections(ea,intersections))
    {
        for(osgUtil::LineSegmentIntersector::Intersections::iterator hitr =
intersections.begin();
            hitr != intersections.end();
            ++hitr)
        {
            std::ostringstream os;
            if (!hitr->nodePath.empty() &&
!(hitr->nodePath.back()->getName().empty()))
            {
                // the geodes are identified by name.
                os<<"Object
\""<<hitr->nodePath.back()->getName()<<"\""<<std::endl;
            }
            else if (hitr->drawable.valid())
            {
                os<<"Object
\""<<hitr->drawable->className()<<"\""<<std::endl;
            }

            os<<"        local coords vertex("<<
hitr->getLocalIntersectPoint()<<")"<<"
 normal("<<hitr->getLocalIntersectNormal()<<")"<<std::endl;
            os<<"        world coords vertex("<<
hitr->getWorldIntersectPoint()<<")"<<"
 normal("<<hitr->getWorldIntersectNormal()<<")"<<std::endl;
            const osgUtil::LineSegmentIntersector::Intersection::IndexList&
vil = hitr->indexList;
            for(unsigned int i=0;i<vil.size();++i)
            {
                os<<"        vertex indices ["<<i<<"] =
"<<vil[i]<<std::endl;
            }

            gdlist += os.str();
        }
    }
    setLabel(gdlist);
}

osg::Camera* createHUD(osgText::Text* updateText)
{
    osg::Camera* hudCamera = new osg::Camera;
    hudCamera->setReferenceFrame(osg::Transform::ABSOLUTE_RF);
    hudCamera->setProjectionMatrixAsOrtho2D(0,1280,0,1024);
    hudCamera->setViewMatrix(osg::Matrix::identity());
    hudCamera->setRenderOrder(osg::Camera::POST_RENDER);
    hudCamera->setClearMask(GL_DEPTH_BUFFER_BIT);

    std::string timesFont("fonts/times.ttf");

    osg::Vec3 position(150.0f,800.0f,0.0f);
    osg::Vec3 delta(0.0f,-60.0f,0.0f);

    {
        osg::Geode* geode = new osg::Geode();
        osg::StateSet* stateset = geode->getOrCreateStateSet();
        stateset->setMode(GL_LIGHTING,osg::StateAttribute::OFF);
        stateset->setMode(GL_DEPTH_TEST,osg::StateAttribute::OFF);
        geode->setName("simple");
        hudCamera->addChild(geode);

        osgText::Text* text = new  osgText::Text;
        geode->addDrawable( text );

        text->setFont(timesFont);
        text->setText("Picking in Head Up Displays is simple!");
        text->setPosition(position);

        position += delta;
    }


    for (int i=0; i<5; i++) {
        osg::Vec3 dy(0.0f,-30.0f,0.0f);
        osg::Vec3 dx(120.0f,0.0f,0.0f);
        osg::Geode* geode = new osg::Geode();
        osg::StateSet* stateset = geode->getOrCreateStateSet();
        const char *opts[]={"One", "Two", "Three", "January", "Feb",
"2003"};
        osg::Geometry *quad=new osg::Geometry;
        stateset->setMode(GL_LIGHTING,osg::StateAttribute::OFF);
        stateset->setMode(GL_DEPTH_TEST,osg::StateAttribute::OFF);
        std::string name="subOption";
        name += " ";
        name += std::string(opts[i]);
        geode->setName(name);
        osg::Vec3Array* vertices = new osg::Vec3Array(4); // 1 quad
        osg::Vec4Array* colors = new osg::Vec4Array;
        colors = new osg::Vec4Array;
        colors->push_back(osg::Vec4(0.8-0.1*i,0.1*i,0.2*i, 1.0));
        quad->setColorArray(colors, osg::Array::BIND_OVERALL);
        (*vertices)[0]=position;
        (*vertices)[1]=position+dx;
        (*vertices)[2]=position+dx+dy;
        (*vertices)[3]=position+dy;
        quad->setVertexArray(vertices);
        quad->addPrimitiveSet(new
osg::DrawArrays(osg::PrimitiveSet::QUADS,0,4));
        geode->addDrawable(quad);
        hudCamera->addChild(geode);

        position += delta;
    }

    { // this displays what has been selected
        osg::Geode* geode = new osg::Geode();
        osg::StateSet* stateset = geode->getOrCreateStateSet();
        stateset->setMode(GL_LIGHTING,osg::StateAttribute::OFF);
        stateset->setMode(GL_DEPTH_TEST,osg::StateAttribute::OFF);
        geode->setName("The text label");
        geode->addDrawable( updateText );
        hudCamera->addChild(geode);

        updateText->setCharacterSize(20.0f);
        updateText->setFont(timesFont);
        updateText->setColor(osg::Vec4(1.0f,1.0f,0.0f,1.0f));
        updateText->setText("");
        updateText->setPosition(position);
        updateText->setDataVariance(osg::Object::DYNAMIC);

        position += delta;
    }
    return hudCamera;
}

osg::Node* createScene() {
osg::ref_ptr<osg::Geode> node = new osg::Geode;
osg::ref_ptr<osg::ShapeDrawable> sphere = new osg::ShapeDrawable(new
osg::Sphere(osg::Vec3(500,300,0), 100));
node->addDrawable(sphere.get());
return node.release();
}

int main( int argc, char **argv )
{
    osg::ref_ptr<osg::Node> scene = createScene();
    osg::ref_ptr<osg::Group> group = new osg::Group;
    osg::ref_ptr<osgText::Text> updateText = new osgText::Text;
osg::ref_ptr<osg::Camera> hud = createHUD(updateText.get());
hud->addChild(scene.get());
//group->addChild(scene.get());
    group->addChild(hud.get());
osgViewer::Viewer viewer;
viewer.addEventHandler(new PickHandler(updateText.get()));
viewer.setSceneData(group.get());
return viewer.run();
}


-- 
Martin
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