Re: [osg-users] ABSOLUTE_RF problem

[Robert Osfield]

HI Guillaume,

2010/7/8 Guillaume Tazé guillaume.t...@gmail.com:
 Hello, i'm trying to understand how ABSOLUTE_RF works, and i've made a small
 example. The problem is that it should works but it actually doesn't...

ABSOLTE_RF means that the when the cull traversal encounters a
Transform node it ignores the inherited modelview matrix so that the
local transform matrix on the Transform node becomes the new modelview
matrix.  This means that the Transform nodes subgraph is placed in new
coordinate frame rather than that of it's parents.

Robert.
___
osg-users mailing list
osg-users@lists.openscenegraph.org
http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org

[osg-users] ABSOLUTE_RF problem

[Guillaume Tazé]

Hello, i'm trying to understand how ABSOLUTE_RF works, and i've made a small
example. The problem is that it should works but it actually doesn't...

In the following lines :

osg::Group * group = new osg::Group();

{ //Relative
osg::PositionAttitudeTransform* pat = new osg::PositionAttitudeTransform();
pat-setPosition(osg::Vec3(-10,0,0));
pat-addChild(osgDB::readNodeFile(cow.osg));
pat-setReferenceFrame(osg::Transform::RELATIVE_RF);
group-addChild(pat);
}

{ //Absolute
osg::PositionAttitudeTransform* pat = new osg::PositionAttitudeTransform();
pat-addChild(osgDB::readNodeFile(cow.osg));
pat-setReferenceFrame(osg::Transform::ABSOLUTE_RF);
//pat-setReferenceFrame(osg::Transform::RELATIVE_RF);
pat-setPosition(osg::Vec3(10,0,0));
group-addChild(pat);
}

group-setEventCallback(new CEventCallback());
viewer.setSceneData(group);
viewer.getCamera()-setCullingMode(osg::CullSettings::CullingModeValues::NO_CULLING);

if i change
pat-setReferenceFrame(osg::Transform::ABSOLUTE_RF);
to
pat-setReferenceFrame(osg::Transform::RELATIVE_RF);

the two cows are here, but when the second pat is absolute, the second cow
won't show... however i can actually pick it if i click on the area where it
should be.

I don't understand why it's not working... can someone helps me ? You can
find the source file attached to this mail.

i've made this test program because i have another problem where i try to
pick an object which is in a pat with ABSOLUTE_RF, and can't make it work (i
can pick all others objects but not the ones with absolute_rf...)

Thanks

---
Guillaume Tazé


Main.cpp
Description: Binary data
___
osg-users mailing list
osg-users@lists.openscenegraph.org
http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org

Re: [osg-users] ABSOLUTE_RF problem

[Robert Osfield]

Hi Pavel,

The RefererenceFrame in Transform is widely used and does work robust
with ABSOLTE_RF - this is how most users with do HUDs (Camera is a
subclass from Transform.)

Just becuase the view matrix is identity doesn't mean that any
subgraph underneath will be visible, far from it, the subgraph will
only be visible if the objects local coordinates place it in front of
the camera.  In your transform set up code place add a query of the
center of the subgraph and then create a transform that takes this to
a position in front of the eye point.

Robert.

On Tue, Jan 27, 2009 at 8:49 AM, Pavel Domša pdo...@seznam.cz wrote:

 Hi all,

 i have an issue with osg::TransformMatrix::SetReferenceFrame and it's either
 bug or my misunderstanding. Documentation on osg::Transform explains
 difference between ABSOLUTE_RF and RELATIVE_RF pretty well. Also
 MatrixTransform.cpp shows how localToWorld transformations are being handled
 for both and code is clear and understandable.

 To demonstrate issue i've created simpliest scenario. Hierarchy is
 root-MatrixTransform-ModelNode(cow). Transformation is identity. By
 default reference frame is RELATIVE_RF and cow is clearly visible. But when
 reference frame is set to ABSOLUTE_RF nothing is being rendered at all. I
 believe that for ABSOLUTE_RF  cow should be visible as well since
 transformation is still identity.

 I googled a lot but it seems that ABSOLUTE_RF is being used only for
 osg::Camera settings and i couldn't find any piece of code where it's set on
 MatrixTransform.

 So is SetReferenceFrame supposed to work on osg::MatrixTransform as well? i
 believe it should because it's very handy to share states and attributes
 from hierarchy above but be able to do transformation in world coords.

 Demo is attached.

 Thanks

 Pavel Domsa


 #include osg/Node
 #include osg/MatrixTransform
 #include osg/Group
 #include osg/BlendFunc
 #include osg/Geometry

 #include osgText/Text
 #include osgViewer/Viewer

 #include osgGA/TrackballManipulator
 #include osgDB/ReadFile
 #include osgViewer/ViewerEventHandlers



 int main( int argc, char **argv )
 {
  osg::Referenced::setThreadSafeReferenceCounting(true);

  int rval = -1;
  osg::ArgumentParser args( argc, argv );

  osg::ref_ptrosg::Node loadedModel = osgDB::readNodeFiles(args);
  if(!loadedModel)
  {
loadedModel = osgDB::readNodeFile(cow.osg);
  }

  std::string filename;

  osgViewer::Viewer viewer;
  viewer.setThreadingModel(osgViewer::Viewer::SingleThreaded);

  viewer.addEventHandler(new osgViewer::WindowSizeHandler);
  viewer.addEventHandler(new osgViewer::StatsHandler);

  osg::ref_ptr osg::Group  scene = new osg::Group;
  viewer.setSceneData( scene.get() );

  osg::ref_ptrosg::MatrixTransform  mxt = new osg::MatrixTransform;

  mxt-addChild(loadedModel.get());

 //  mxt-setReferenceFrame(osg::Transform::ABSOLUTE_RF); // uncomment here

  scene-addChild(mxt.get());

  viewer.setCameraManipulator(new osgGA::TrackballManipulator());

  viewer.run();

  return( rval );
 }


 ___
 osg-users mailing list
 osg-users@lists.openscenegraph.org
 http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org


___
osg-users mailing list
osg-users@lists.openscenegraph.org
http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org