Hi Robert, Thanks for your reply. What I'm trying to do is to map window
coordinates to object coordinates, but I got incorrect results using the
matrices given by viewer.getCamera().getViewport().computeWindowMatrix(),
viewer.getCamera().getProjectionMatrix() and
viewer.getCamera().getViewMatrix(). So I referred to the OSG source code and
tried the code in my initial email. I didn't know about the matrix stack
methods then.
After obtaining the mapped object coordinates, I need to construct a ray from
the viewer's position. The position and the ray then can be used to create a
mouse picking line segment.
My code is like this:
protected unsafe bool pick(OsgGA.GUIEventAdapter ea, OsgViewer.Viewer viewer){
......
Osg.Matrix VPW = new Matrix();
Osg.Matrix inverseVPW = new Matrix();
Vec3d windowPositionStart = new Vec3d((double)(ea.getXnormalized()),
(double)(ea.getYnormalized()), -1.0d);
Vec3d windowPositionEnd = new Vec3d((double)(ea.getXnormalized()),
(double)(ea.getYnormalized()), 1.0d);
Vec3d worldPositionStart = new Vec3d();
Vec3d worldPositionEnd = new Vec3d();
VPW.preMult(viewer.getCamera().getProjectionMatrix());
VPW.preMult(viewer.getCamera().getViewMatrix());
inverseVPW = Osg.Matrix.inverse(VPW);
worldPositionStart = windowPositionStart * inverseVPW;
worldPositionEnd = windowPositionEnd * inverseVPW;
Vec3d ray1 = new Vec3d(worldPositionEnd[0]-worldPositionStart[0],
worldPositionEnd[1]-worldPositionStart[1],
worldPositionEnd[2]-worldPositionStart[2]);
ray1.normalize();
Vec3 eye = new Vec3();
Vec3 center = new Vec3();
Vec3 up = new Vec3();
viewer.getCamera().getViewMatrixAsLookAt(ref eye, ref center,ref up);
Vec3d ray2 = new Vec3d(eye[0]-worldPositionStart[0],
eye[1]-worldPositionStart[1], eye[2]-worldPositionStart[2]);
ray2.normalize();
....
}
results:
1. ray1 always equals {0.0, 0.0, 1.0} after any zooming, rotating, and panning;
2. ray2 remains almost the same after any zooming, rotating, and panning;
3. worldPositionStart looks like the mapping of the screen position. Since I'm
using perspective projection, worldPositionStart and worldPositionEnd are
slightly different.
questions:
1. why ray1 remains constant?
2. is ray2 what I need in this case?
3. is the near clipping plane at z=-1.0 in OSG?
I know what I'm trying to do is kind of simple, but I have been struggling for
a while and cannot get the correct results yet.
Thanks, and regards,
Ke Li
> Date: Sat, 15 Mar 2008 10:19:05 +0000> From: [EMAIL PROTECTED]> To:
> [email protected]> Subject: Re: [osg-users] Problem with
> using IntersectionVisitor to obtain the viewing matrices> > Hi Ke Li,> > I'm
> confused by your code and what you are trying to do.> > The matrix stack
> methods in IntersectionVisitor are there for internal> usage during the
> traversal of the scene graph, as the traversal goes> down matrices are pushed
> on the respective stacks, and on the return> up these matrices are popped.
> Once the traversal is complete the> stacks will be empty unless you've pushed
> ones on yourself.> > So the quesition still has to be what are you trying to
> do? What do> you need the matrices for?> > Robert.> > > On Fri, Mar 14, 2008
> at 9:31 PM, Ke Li <[EMAIL PROTECTED]> wrote:> >> > Dear all,> >> > I'm trying
> to obtain the model matrix, the view matrix, the projection> > matrix and the
> window matrix. I used the following piece of code in my pick> > event
> handler.> >> > protected unsafe bool pick(OsgGA.GUIEventAdapter ea,
> OsgViewer.Viewer> > viewer)> > {> > ......> > picker = new> >
> OsgUtil.LineSegmentIntersector(OsgUtil.Intersector.CoordinateFrame.PROJECTION,>
> > ea.getXnormalized(), ea.getYnormalized());> > OsgUtil.IntersectionVisitor
> iv = new> > OsgUtil.IntersectionVisitor(picker);> >
> viewer.getCamera().accept(iv);> >> > Osg.Matrix VPW = new Matrix();> > if
> (iv.getWindowMatrix()!=null)> > {> > Osg.Matrix mm = new> >
> Osg.Matrix(iv.getWindowMatrix().ptr());> > VPW.preMult(mm);> > }> > if
> (iv.getProjectionMatrix() != null)> > {> > Osg.Matrix mm = new> >
> Osg.Matrix(iv.getProjectionMatrix().ptr());> > VPW.preMult(mm);> > }> > if
> (iv.getViewMatrix() != null)> > {> > Osg.Matrix mm = new> >
> Osg.Matrix(iv.getViewMatrix().ptr());> > VPW.preMult(mm);> > }> > if
> (iv.getModelMatrix() != null)> > {> > Osg.Matrix mm = new> >
> Osg.Matrix(iv.getModelMatrix().ptr());> > VPW.preMult(mm);> > }> > ......> >
> }> >> > But the iv object could never return any matrix and all the Boolean>
> > expression in the if statement always equal to false.> >> > I'm wondering
> what is wrong here. Is there any thing else that I need to do> > before I can
> obtain the matrices?> >> > Any help is appreciated!> >> > Regards,> >> > Ke
> Li> >> >> >> > ________________________________> > Connect and share in new
> ways with Windows Live. Get it now!> >
> _______________________________________________> > osg-users mailing list> >
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> http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org> >>
> >> _______________________________________________> osg-users mailing list>
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