[osg-users] Positioning the viewers camera
Kaiser, Hagen (CT)
Hello everyone,
I am desparately trying to position a viewers camera manually and correctly.
My give data give me a Position Vector a RotationAxis and a Rotation Angle.
And a float that is named fieldofView.
Here is how I implement it:
osgGA::TrackballManipulator* man = (osgGA::TrackballManipulator*)this->viewer->getCameraManipulator();
osg::Matrix trans;
trans.makeTranslate(osg::Vec3(position.x(),position.y(),position.z()));
osg::Matrix rot;
rot.makeRotate(Angle,osg::Vec3(Axis.x,Axis.y,Axis.z)));
osg::Matrix cam = rot*trans;
this->viewer->setByMatrix(cam)
}
But I never get the right position or rotation.
After testing around, I noticed the following:
Changing
trans.makeTranslate(…
to trans.makeTranslate(osg::Vec3(position.x, -position.z, position.y));
I somehow get the right position.
But the right rotation??
I found a tutorial somewhere, where it says Everything under osgGa:: Namespace has another AxisOrientation.
And in the tutorial there is something said about producer::rotate.
What is Producer. This namespace doesnt even exist in OpenSceneGraph;
Please help!!
Thx in advance
Greetings to everyone
Alejandro Segovia
Hello everyone,
I am desparately trying to position a viewers camera manually and correctly.
My give data give me a Position Vector a RotationAxis and a Rotation Angle.
And a float that is named fieldofView.
Here is how I implement it:
osgGA::TrackballManipulator* man = (osgGA::TrackballManipulator*)this->viewer->getCameraManipulator();
osg::Matrix trans;
trans.makeTranslate(osg::Vec3(position.x(),position.y(),position.z()));
osg::Matrix rot;
rot.makeRotate(Angle,osg::Vec3(Axis.x,Axis.y,Axis.z)));
osg::Matrix cam = rot*trans;
this->viewer->setByMatrix(cam)
}
But I never get the right position or rotation.
After testing around, I noticed the following:
Changing
trans.makeTranslate(…
to trans.makeTranslate(osg::Vec3(position.x, -position.z, position.y));
cam = rot*trans seems fine.
Let me know how it went.
Alejandro.-
--
Varrojo@Linux
http://varrojo.linuxuruguay.org
Kaiser, Hagen (CT)
To position a camera manually, we can use the viewer class setViewByMatrix() method. This call should be placed between the viewer.update and viewer.frame calls within the simulation loop. The following guidelines are useful:
- Producer and all classes below osgGA::MatrixManipulator (in terms of abstraction) use 'Y' up coordinates. All others -including the Viewer class matrix manipulators - use 'Z' up.
- The inverse of a position/orientation matrix can be used to orient a camera.
Gesendet: Freitag, 6. Juni 2008 16:24
An: OpenSceneGraph Users
Betreff: Re: [osg-users] Positioning the viewers camera
Paul Melis
> Thanks for the idea,
> But that doesnt seem to bring me any furhter.
> Coordinates are somthing like 500, -5,50 so making this all minus
> brings me so far away, that i cant see anything anymore
> This is what I found in atutorial about that problem:
>
> To position a camera manually, we can use the viewer class
> setViewByMatrix() method. This call should be placed between the
> viewer.update and viewer.frame calls within the simulation loop. The
> following guidelines are useful:
>
> * Producer and all classes below osgGA::MatrixManipulator (in
> terms of abstraction) use 'Y' up coordinates. All others
> -including the Viewer class matrix manipulators - use 'Z' up.
> * The inverse of a position/orientation matrix can be used to
> orient a camera.
>
> This correseponds to my makeTranslate call, I think.
Just a check: is the rotation value you apply in degrees or radians?
makeRotate() expects a value in radians...
Paul
> ------------------------------------------------------------------------
> *Von:* osg-user...@lists.openscenegraph.org
> [mailto:osg-user...@lists.openscenegraph.org] *Im Auftrag von
> *Alejandro Segovia
> *Gesendet:* Freitag, 6. Juni 2008 16:24
> *An:* OpenSceneGraph Users
> *Betreff:* Re: [osg-users] Positioning the viewers camera
>
> Hello,
>
> On Fri, Jun 6, 2008 at 11:10 AM, Kaiser, Hagen (CT)
> <hagen....@siemens.com <mailto:hagen....@siemens.com>> wrote:
>
>
> Hello everyone,
> I am desparately trying to position a viewers camera manually and
> correctly.
> My give data give me a Position Vector a RotationAxis and a
> Rotation Angle.
> And a float that is named fieldofView.
> Here is how I implement it:
> osgGA::TrackballManipulator* man =
> (osgGA::TrackballManipulator*)this->viewer->getCameraManipulator();
> osg::Matrix trans;
> trans.makeTranslate(osg::Vec3(position.x(),position.y(),position.z()));
> osg::Matrix rot;
> rot.makeRotate(Angle,osg::Vec3(Axis.x,Axis.y,Axis.z)));
> osg::Matrix cam = rot*trans;
> this->viewer->setByMatrix(cam)
> }
> But I never get the right position or rotation.
> After testing around, I noticed the following:
> Changing
> trans.makeTranslate(…
> to trans.makeTranslate(osg::Vec3(position.x,* -position.z,
> position.y*));
>
> Have you tried making a translation of (-x, -y, -z) instead? Remember
> that placing the camera at some point P is actually applying a
> translation of -P to the whole world.
>
> cam = rot*trans seems fine.
>
> Let me know how it went.
>
> Alejandro.-
>
> --
> Varrojo@Linux
> http://varrojo.linuxuruguay.org
>
>------------------------------------------------------------------------
>
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>
>
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Kaiser, Hagen (CT)
But do you know something about those diffent Up-Vectors?
-----Ursprüngliche Nachricht-----
Von: osg-user...@lists.openscenegraph.org [mailto:osg-user...@lists.openscenegraph.org] Im Auftrag von Paul Melis
Gesendet: Freitag, 6. Juni 2008 16:36
An: OpenSceneGraph Users
Betreff: Re: [osg-users] Positioning the viewers camera
Kaiser, Hagen (CT) wrote:
Paul
> trans.makeTranslate(...
Alejandro Segovia
It is in radians.
But do you know something about those diffent Up-Vectors?
I didn't notice those vectors were different since I user SceneView directly, instead of osgViewer::Viewer.
You can change the coordinate system for all these objects by creating your own CoordinateFrameCallback class whose getCoordinateFrame method returns a matrix corresponding to whatever you want the Axes to be. The coordinate frame callback can be passed to the MatrixManipulators to change what they "think" the axes are like.
Zoltán
> It is in radians.
> But do you know something about those diffent Up-Vectors?
This is a basic convenion:
- the World (incl OSG) uses X-Y horizontal plane, and Z is
vertical (UP)
- opticians use X-Y as the plane you look at (like the
screen) and Z is the depth (ever heard about a Z-buffer ?)
So "UP" is in the world the Z axis (0,0,1) and Y axis
(0,1,0) in optics, like a camera
Zoltán
> >----------------- *Von:*
> > osg-user...@lists.openscenegraph.org
> > [mailto:osg-user...@lists.openscenegraph.org] *Im
> > Auftrag von *Alejandro Segovia
> > *Gesendet:* Freitag, 6. Juni 2008 16:24
> > *An:* OpenSceneGraph Users
> > *Betreff:* Re: [osg-users] Positioning the viewers
> > camera
> >
> > Hello,
> >
> > On Fri, Jun 6, 2008 at 11:10 AM, Kaiser, Hagen (CT)
> > <hagen....@siemens.com
> > <mailto:hagen....@siemens.com>> wrote:
> >
> >
> > Hello everyone,
> > I am desparately trying to position a viewers
> > camera manually and correctly.
> > My give data give me a Position Vector a
> > RotationAxis and a Rotation Angle.
> > And a float that is named fieldofView.
> > Here is how I implement it:
> > osgGA::TrackballManipulator* man =
> >
> > (osgGA::TrackballManipulator*)this->viewer->getCameraMa
> >nipulator(); osg::Matrix trans;
> >
> > trans.makeTranslate(osg::Vec3(position.x(),position.y()
> >,position.z())); osg::Matrix rot;
--
____________________________________
Zoltan
http://sourceforge.net/projects/zsim
____________________________________
Paul Melis
>It is in radians.
>But do you know something about those diffent Up-Vectors?
>
>
Well, the default "camera" orientation for OpenGL (i.e. when the
model-view matrix is the identity matrix) is to have the camera at the
origin, with Y being up, and the camera looking down the negative
Z-axis. This also applies to the MatrixManipulator classes. So if a
manipulator returns the identity matrix the view will have Y up.
However, the manipulator classes in OSG seem to default (i.e. home
position when pressing the space bar) to return a matrix in which Z is
up. So the matrix they return includes as a first step a rotation around
the X around by 90 degrees to turn Y up in Z up. More confusing is the
fact that the _inverse matrix_ returned by a matrix manipulator is
actually used as the model-view matrix.
Hmm, I hope I got this all correct, it's so easy to make a mistake with
this stuff...
BTW, you don't have to use a matrix manipulator, as it seems you want
full control over the view orientation (and assuming mouse interaction
is unwanted). In that case you can do
viewer->getCamera()->setViewMatrix(...)
within the frame loop and set your desired model-view matrix there.
Paul
Paul Melis
> Kaiser, Hagen (CT) wrote:
>
>> It is in radians.
>> But do you know something about those diffent Up-Vectors?
>>
>>
> Well, the default "camera" orientation for OpenGL (i.e. when the
> model-view matrix is the identity matrix) is to have the camera at the
> origin, with Y being up, and the camera looking down the negative
> Z-axis. This also applies to the MatrixManipulator classes. So if a
> manipulator returns the identity matrix the view will have Y up.
> However, the manipulator classes in OSG seem to default (i.e. home
> position when pressing the space bar) to return a matrix in which Z is
> up. So the matrix they return includes as a first step a rotation
> around the X around by 90 degrees to turn Y up in Z up. More confusing
> is the fact that the _inverse matrix_ returned by a matrix manipulator
> is actually used as the model-view matrix.
To clearify: what is returned by a manipulator with getInverseMatrix()
is used as the model-view matrix
Paul