Re: [osg-users] Arcball Camera without unexpecting 'roll' of the camera
On Tue, May 17, 2016 at 2:35 PM, Daniel Neos wrote: > Unfortunalety there is no feature "throw" feature. My class inherits from > osgGA::GUIEventHandler and there is no setAllowThrow implemented, as far as > I know. > > And if I am zooming in, sometimes the effect gets worse and the camera is > hardly to control. Maybe there is an error in my rotation setup? > That sounds like a classic case of gimbal lock to me. You are rotating using 2 Euler angles rotations, so it is easy to align the axes in exactly "the wrong way" and trigger the singularity when approaching +- 90 degrees. You may want to look at this code: https://en.wikibooks.org/wiki/OpenGL_Programming/Modern_OpenGL_Tutorial_Arcball J. ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] Arcball Camera without unexpecting 'roll' of the camera
Unfortunalety there is no feature "throw" feature. My class inherits from
osgGA::GUIEventHandler and there is no setAllowThrow implemented, as far as I
know.
Here is (part of) my actual mouse dragging code:
Code:
bool CameraHandler::handle(const osgGA::GUIEventAdapter & ea,
osgGA::GUIActionAdapter & us)
{
osgViewer::View* viewer = dynamic_cast(&us);
osg::Matrixd viewMatrix = viewer->getCamera()->getViewMatrix();
osg::Vec3d translation = viewMatrix.getTrans();
osg::Matrixd rotationX = osg::Matrix::rotate(deltaX * 0.5,
osg::Y_AXIS);
osg::Matrixd rotationY = osg::Matrix::rotate(-deltaY * 0.5,
osg::X_AXIS);
osg::Matrixd preTrans = osg::Matrix::identity();
osg::Matrixd postTrans = osg::Matrix::identity();
osg::Vec3d bsCenter = osg::Vec3d(137.69, 284.17, 3305.0); //
scene is (almost) static
m_rotationPoint = osg::Vec3(0.0, 0.0 , 0.0); // good rotation
point for
m_rotationPoint = translation - bsCenter; // good rotation
point for
preTrans.setTrans(-m_rotationPoint);
postTrans.setTrans(m_rotationPoint);
viewMatrix = viewMatrix * (preTrans * rotationX * rotationY *
postTrans);
viewer->getCamera()->setViewMatrix(viewMatrix);
// ensure fixed point to look at
osg::Vec3d eye, center, up;
viewer->getCamera()->getViewMatrixAsLookAt(eye, center, up);
if (focusPointFlag)
{
viewer->getCamera()->setViewMatrixAsLookAt(eye, bsCenter ,
up);
}
return true;
}
And if I am zooming in, sometimes the effect gets worse and the camera is
hardly to control. Maybe there is an error in my rotation setup?
Thank you!
Cheers
Daniel Neos
cbuchner1 wrote:
> Could it be that the "throw" feature of the camera manipulator is responsible
> for the roll?
>
> If so, try disabling it.
>
>
> Also, post source code if you want specific help with a specific issue in
> your implementation.
>
>
> Christian
>
>
>
>
Code:
--
Read this topic online here:
http://forum.openscenegraph.org/viewtopic.php?p=67128#67128
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Re: [osg-users] Arcball Camera without unexpecting 'roll' of the camera
Could it be that the "throw" feature of the camera manipulator is responsible for the roll? If so, try disabling it. Also, post source code if you want specific help with a specific issue in your implementation. Christian 2016-05-16 14:59 GMT+02:00 Daniel Neos : > Hi everyone, > > I have implemented a Cameramanipulator by myself, because I need more > individually control over the camera in the scene, like rotating around a > specific axis. > > I let osg compute the Boundingsphere of my scene and set the rotationpoint > and the lookat-point or center-point at the center of the Boundingsphere. > > My rotation works like this > > 1.) Translate the camera to the center of the Boundingsphere > (Multiplicated from the right side of the viewmatrix of the camera fist) > > 2.) Rotate the viewmatrix by the OSG::x_axis and OSG::y_axis (depending on > the mousemovement) > > 3.) Translate the camera back with the vector from step 1. > > 4.) Now with the last step I ensure, that the camera stays focused at the > samepoint by getting the eye, center and up vector and reseting the center > vector, while eye and up remains the same. > > This usually works fine and it is easy to navigate through the scene with > the mouse, but as I reach some regions the camera unexpectedly seem to > rotate around its own z-axis which results in to a 'roll'. > > How can I prevent this behaviour? Sample code with arcball camera would be > appreciated too :) > > Thank you! > > Cheers, > Daniel > > -- > Read this topic online here: > http://forum.openscenegraph.org/viewtopic.php?p=67113#67113 > > > > > > ___ > 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
[osg-users] Arcball Camera without unexpecting 'roll' of the camera
Hi everyone, I have implemented a Cameramanipulator by myself, because I need more individually control over the camera in the scene, like rotating around a specific axis. I let osg compute the Boundingsphere of my scene and set the rotationpoint and the lookat-point or center-point at the center of the Boundingsphere. My rotation works like this 1.) Translate the camera to the center of the Boundingsphere (Multiplicated from the right side of the viewmatrix of the camera fist) 2.) Rotate the viewmatrix by the OSG::x_axis and OSG::y_axis (depending on the mousemovement) 3.) Translate the camera back with the vector from step 1. 4.) Now with the last step I ensure, that the camera stays focused at the samepoint by getting the eye, center and up vector and reseting the center vector, while eye and up remains the same. This usually works fine and it is easy to navigate through the scene with the mouse, but as I reach some regions the camera unexpectedly seem to rotate around its own z-axis which results in to a 'roll'. How can I prevent this behaviour? Sample code with arcball camera would be appreciated too :) Thank you! Cheers, Daniel -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=67113#67113 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
