Hi Fred,
OSG does compute the correct near/far values for pre-render cameras,
assuming it is enabled for it. As you can tell, the main problem is getting
access to the computed projection matrix. What I have done to get the
computed near/far values from camera nodes is to attach a cull callback to
the camera that retrieves the computed projection matrix from the cull
visitor after the camera has been traversed. The cull callback function
looks something like this:
void MyCullCallback::operator()(osg::Node* node, osg::NodeVisitor* nv)
{
if (nv->getVisitorType() == osg::NodeVisitor::CULL_VISITOR) {
osgUtil::CullVisitor* cv = dynamic_cast<osgUtil::CullVisitor*>(nv);
if(cv) {
traverse(node,nv);
cv->computeNearPlane();
if (cv->getComputeNearFarMode() && cv->getCalculatedFarPlane()
>= cv->getCalculatedNearPlane()) {
osgUtil::CullVisitor::value_type znear =
cv->getCalculatedNearPlane();
osgUtil::CullVisitor::value_type zfar =
cv->getCalculatedFarPlane();
//Do something with znear/zfar values
}
return;
}
}
traverse(node,nv);
}
This works really well for my application. I think every time I've
encountered some tricky problem like this, cull callbacks were the
solution. I don't know what I would do without them :)
Cheers,
Farshid
On Mon, Jun 3, 2013 at 9:00 AM, Fred Smith <[email protected]> wrote:
> Robert,
>
> Sorry to further fill in this thread with a question - but couldn't it be
> that the OSG indeed correctly calculates the near/far values for my
> pre_render camera, and that I simply just do not know (yet) a proper way to
> correctly retrieve the projection matrix? I see the CullVisitor calculates
> the near/far values, maybe I should hook into this and grab the values from
> there?
> Any hint is appreciated really, and again sorry for the verbose thread.
>
> Cheers,
> Fred
>
> ------------------
> Read this topic online here:
> http://forum.openscenegraph.org/viewtopic.php?p=54407#54407
>
>
>
>
>
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>
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