Hi,
I am trying to use the excellent application from osgworks - osgwbvv to draw
bounding spheres around any particular selected node in the scene graph.
The function used to draw the bounding sphere is below:
Code:
void OsgViewerWindow::drawBoundingSphere(osg::ref_ptr<osg::Node> &node)
{
osg::MatrixList matrixList = node->getWorldMatrices();
osg::ref_ptr<osg::MatrixTransform> boundingBoxMt = new osg::MatrixTransform();
osg::ref_ptr<osg::Geode> boundingBoxGeode = new osg::Geode();
osg::StateSet* ss = boundingBoxGeode->getOrCreateStateSet();
ss->setAttributeAndModes( new osg::PolygonMode(
osg::PolygonMode::FRONT_AND_BACK, osg::PolygonMode::LINE ) );
ss->setMode( GL_LIGHTING, osg::StateAttribute::OFF );
const osg::BoundingSphere bs( node->getBound() );
boundingBoxMt->postMult(osg::Matrix::rotate(matrixList[0].getRotate())*
osg::Matrix::translate(bs._center +
matrixList[0].getTrans()) );
//add drawable to the geode
boundingBoxGeode->addDrawable( osgwTools::makeGeodesicSphere( bs._radius, 1 )
);
//add geode under Mt
boundingBoxMt->addChild(boundingBoxGeode);
//get the parent matrix transform of the node and add bounding sphere to it
node->getParent(0)->addChild(boundingBoxGeode);
return;
}
While this works fine when there are translations applied to the
MatrixTransforms above the nodes, the bounding spheres do not enclose the
geometry when rotations are added to the mix. Actually, rendering the bounding
sphere clearly showed that something was wrong.
I tried following some of the threads as there was some mention of rotations in
transforms leading to incorrect results. I thought I was doing ok but haven't
had much success. Hence I wanted to ask what is the correct approach to get the
bounding sphere for a particular node which may have rotations in addition to
translation and scale.
Thanks
Sincerely,
Sanat.
------------------
Read this topic online here:
http://forum.openscenegraph.org/viewtopic.php?p=42174#42174
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