Hallo Martin,
After I saw your mail I put up a little example program which does what you
want (i think).
Basically it prints the screen space coordinates of the center of the 3d
sphere, which is in world space (0,0,0).
Use the normal osgViewer mouse controls to move the sphere model around.
Just copy the code and look at the print outs. I used a modified example from
osghelp.com
Enjoy
Dimi
#include osgViewer/Viewer
#include osgGA/GUIEventHandler
#include osg/ShapeDrawable
#include osg/PositionAttitudeTransform
#include osg/LineSegment
#include osgUtil/IntersectVisitor
#includestdio.h
class CInputHandler : public osgGA::GUIEventHandler
{
public:
CInputHandler( osg::PositionAttitudeTransform* pPatSphere, osg::Node*
pGraph )
{
m_rPatSphere = pPatSphere;
m_rGraph = pGraph;
}
virtual bool handle( const osgGA::GUIEventAdapter ea,
osgGA::GUIActionAdapter aa, osg::Object* pObject, osg::NodeVisitor*
pNodeVisitor )
{
osgViewer::Viewer* pViewer = dynamic_castosgViewer::Viewer*(aa);
if ( !pViewer )
{
return false;
}
// normalized mouse position
float x = ea.getXnormalized();
float y = ea.getYnormalized();
osg::Matrixd proj = pViewer-getCamera()-getProjectionMatrix();
osg::Viewport* viewport = pViewer-getCamera()-getViewport();
double mx = viewport-x() + (int)((double
)viewport-width()*(x*0.5+0.5));
double my = viewport-y() + (int)((double
)viewport-height()*(y*0.5+0.5));
osg::Matrix MVPW = pViewer-getCamera()-getViewMatrix() * proj;
MVPW.postMult(
pViewer-getCamera()-getViewport()-computeWindowMatrix() );
osg::Vec3 nearPoint = osg::Vec3(0.f,0.f,0.0f) * MVPW;
printf(Screen Space: %f %f\n, nearPoint[0], nearPoint[1]);
return false;
}
private:
osg::ref_ptrosg::PositionAttitudeTransform m_rPatSphere;
osg::ref_ptrosg::Node m_rGraph;
};
osg::Node* CreateScene( osgViewer::Viewer* pViewer )
{
// create a group to contain our floor and sphere
osg::Group* pGroup = new osg::Group;
// create floor
osg::Geode* pGeodeFloor = new osg::Geode;
pGeodeFloor-addDrawable( new osg::ShapeDrawable( new
osg::Box(osg::Vec3(0.0f,0.0f,-0.5f),100.0f, 100.0f, 1.0f) ) );
pGroup-addChild( pGeodeFloor );
// create sphere
osg::Geode* pGeodeSphere = new osg::Geode;
pGeodeSphere-addDrawable( new osg::ShapeDrawable( new
osg::Sphere(osg::Vec3(0.0f,0.0f,0.0f),5.0f) ) );
// create transform to move sphere
osg::PositionAttitudeTransform* pPat = new osg::PositionAttitudeTransform;
pPat-addChild( pGeodeSphere );
pGroup-addChild( pPat );
// add the handler to the viewer
pViewer-addEventHandler( new CInputHandler(pPat, pGeodeFloor ) );
return pGroup;
}
int main(int argc, char* argv[])
{
// construct the viewer
osg::ref_ptrosgViewer::Viewer rViewer = new osgViewer::Viewer;
// make the viewer create a 512x512 window and position it at 32, 32
rViewer-setUpViewInWindow( 32, 32, 512, 512 );
// set the scene-graph data the viewer will render
rViewer-setSceneData( CreateScene( rViewer.get() ) );
// execute main loop
return rViewer-run();
}
- Original Message -
From: Sebastian Messerschmidt sebastian.messerschm...@gmx.de
To: osg-users@lists.openscenegraph.org
Cc: Martin Haffner str...@gmx.net
Sent: Thursday, December 8, 2011 11:19 AM
Subject: Re: [osg-users] World to Screen Space
Hello Martin,
there are some things I'd check:
1. Transformation order (i'm not quite sure about the osg::Matrix order)
So try mat * vec instead of vec* mat
2. viewMat, this should take you from object space to view-space if I'm
not mistaken.
So if you really have world-space you just need the view-transform here.
Basically I'd setup an simple example and check the matrices. Start with
a simple translation etc.
As you don't state what exactly is wrong, I guess no one will be able to
simply solve your problem.
cheers
Sebastian
Hi,
I want to transform a point from world space to screen space with this code:
Camera* cam = ...
Matrix viewMat = cam-getViewMatrix();
Matrix projMat = cam-getProjectionMatrix();
Viewport* vp = cam-getViewport();
Matrix vpMat = vp-computeWindowMatrix();
Vec3 ls1SS = ls1WSPos * viewMat * projMat * vpMat;
Unfortunately the result vector ls1SS is not correct. Is my approach
generelly right or did I miss something?
Thank you!
Cheers,
Martin
--
Read this topic online here:
http://forum.openscenegraph.org/viewtopic.php?p=44277#44277
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