Hi Gianni,
On 03.11.2014 10:37, Gianni Ambrosio wrote:
> Hi All,
> I'm trying to handle mouse movements to show some informations to the user.
> I have basically two questions.
>
> 1) Lookig at "osgkeyboardmouse.cpp" example found the following code:
>
> Code:
>
> if (_useWindowCoordinates)
> {
> // use window coordinates
> // remap the mouse x,y into viewport coordinates.
> osg::Viewport* viewport = viewer->getCamera()->getViewport();
> double mx = viewport->x() + (int)((double
> )viewport->width()*(ea.getXnormalized()*0.5+0.5));
> double my = viewport->y() + (int)((double
> )viewport->height()*(ea.getYnormalized()*0.5+0.5));
>
> // half width, height.
> double w = 5.0f;
> double h = 5.0f;
> picker = new osgUtil::PolytopeIntersector(
> osgUtil::Intersector::WINDOW, mx-w, my-h, mx+w, my+h );
> } else {
> double mx = ea.getXnormalized();
> double my = ea.getYnormalized();
> double w = 0.05;
> double h = 0.05;
> picker = new osgUtil::PolytopeIntersector(
> osgUtil::Intersector::PROJECTION, mx-w, my-h, mx+w, my+h );
> }
>
>
>
> Is there a casa in which osgUtil::Intersector::WINDOW option is preferred
> with respect to osgUtil::Intersector::PROJECTION?
The window coordinates will give you a pixel based pick area whereas the
projection coordinates
work on normalized [-1,1] coordinates.
If your application supports different screen resolutions it might be more
intuitive for the user
to use window coordinates.
> 2) osgUtil::LineSegmentIntersector does not seem to work fine if the geometry
> is a line created with:
>
> osg::Vec3Array* vertices = new osg::Vec3Array;
> ...
> osg::DrawElementsUInt* elements = new
> osg::DrawElementsUInt(osg::PrimitiveSet::LINE_STRIP);
> geometry->setVertexArray(vertices);
> geometry->addPrimitiveSet(elements);
>
> In this case when I move the mouse over that geometry I get
> containsIntersections() = false.
> Could you please explain me why?
LineSegementIntersector only handles primitives that cover a 2d-area
(triangle/quad-strip/sets and such).
PolytopeIntersector can handle all primitives but it slower for 2d primitives.
> Regards,
> Gianni
Best regards,
Peter
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