[osg-users] Camera shaking

Per Nordqvist nordqvist at gmail.com
Wed Jul 9 01:34:18 PDT 2008


Hi Vincent,

Just a guess:
You may want to doublecheck that actionBetweenFrames is not switching
the node which contains the update callback. That could cause all kinds
of shaking.

Regards,

/Per

2008/7/9 Vincent Bourdier <vincent.bourdier at gmail.com>:
> Hi all,
>
> I have a similar problem than
> http://lists.openscenegraph.org/pipermail/osg-users-openscenegraph.org/2008-June/012275.html
> but I did not succed to solve the problem...
>
> This is the whole problem :
>
> I've done a manipulator (matrix manipulator), which permit to make the
> camera follow a node.
> The node is moved by an UpdateCallback on a other node.
> The manipulator's camera position is computed in a _frame() method :
>
>> bool MyManipulator::handle(const osgGA::GUIEventAdapter& ea,
>> osgGA::GUIActionAdapter& us){
>> [...]
>> case(osgGA::GUIEventAdapter::FRAME):
>>             _frame();
>> [...]
>> }
>
> In the frame method, I get the world position of the node, and set the
> camera's position doing something like this :
>
>> osg::Matrixd MyManipulator::getInverseMatrix() const{
>>         return
>> osg::Matrixd::translate(_eye+_vCorrectionGoto)*osg::Matrixd::rotate((_rotation).inverse());
>> }
>
> with eye = eye + node_translation
>
> my render loop is :
>
>> while(!pViewer->done() && !masterKilled )
>>          {
>>              pViewer->advance();
>>              pViewer->eventTraversal();
>>              pViewer->updateTraversal();
>>
>>              actionBetweenFrames(contextID); //just update some node in
>> the scene graph (switch add and remove child)
>>              pViewer->renderingTraversals();
>>           }
>
> But when I put the camera behind a node, the camera is shaking in the axis
> translation (not allong Z axis when node is moving in XY plane)... It looks
> something must un-synchronized...
>
> Any idea ?
>
> thanks.
>
> Regards,
>
> Vincent
>
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