Thank you both for your feedback. I have looked at the HUD example
before and I use a post-render camera for my own HUD-type display.
Unless I've missed something, that is the only kind of camera in the HUD
example.
As Guy suggested, here is the relative code section (the osgGroup() is a
group for this node):
Constructor()
{
m_camera = new osg::Camera;
osgGroup()->addChild(m_camera.get());
m_camera->setReferenceFrame(osg::Transform::ABSOLUTE_RF);
m_camera->setViewMatrix(osg::Matrix::identity());
m_camera->setClearMask(0);
m_camera->setRenderOrder(osg::Camera::NESTED_RENDER);
osg::Geode* geode = new osg::Geode;
m_camera->addChild(geode);
geode->setCullingActive(false);
// Geometry...
// StateSet...
}
Update()
{
m_camera->setProjectionMatrixAsOrtho2D(0.0, viewportWidth, 0.0,
viewportHeight);
// Update geometry...
}
As is typical when finally sending a mail for help, I sure thought I had
tried this exact combination (suggested my Guy in his message).
Nonetheless, I believe this code will work for me. I'll have to check
when I go to work and plug it into the large scene graph, but it seems
to accomplish what I want in my smaller test setup. I knew I couldn't be
that far off from the right answer.
Thank you, I'll let you know how this ends up working.
John Cummings
Robert Osfield wrote:
> Hi John,
>
> An in scene graph osg::Camera is certainly the route you'd want to
> take, the osghud example is probably a good place to start. You can
> assign your own Viewport to an scene graph osg::Camera, but if you
> don't it'll just inherit it's parent Camera's Viewport. osg::Camera
> also allows you to control which of the frame buffer components to
> clear, if you don't want to clear anything just use
> camera->setClearMask(0);
>
> Robert.
>
> On Tue, Mar 17, 2009 at 7:31 AM, John Cummings
> <[email protected] <mailto:[email protected]>> wrote:
>
> First, I'm using OSG 2.8.0
>
> I'm have been porting an old application from a homegrown OpenGL
> scene-graph to osg and I've come across an issue that I'm sure
> there is
> a way to handle, but I seem to be unable to locate just the right
> combination of Camera, Drawables, etc.
>
> While most of the old nodes are simply geometry nodes, some of them do
> their own Projection before issuing geometry-type calls. I may want to
> do this for a variety of reasons, including allowing finer grained
> control of the depth buffer or simply covering over something that has
> already been drawn. In my old OpenGL code, the render method for
> one of
> these problem nodes may look something like:
>
> void MyNode::Render()
> {
> glMatrixMode(GL_PROJECTION);
> glPushMatrix();
> glLoadIdentity();
>
> // Then either:
> glOrtho (...);
> // or
> gluPerspective(...);
> // or
> glFrustrum();
>
> glMatrixMode(GL_MODELVIEW);
>
> // begin, end, etc.
>
> glMatrixMode(GL_PROJECTION);
> glPopMatrix();
> glMatrixMode(GL_MODELVIEW);
>
> RenderChildren();
> }
>
> I've played with the Camera node and "NESTED_RENDER" seemed from its
> name to be what I wanted. That is, I though I could simply attach an
> osg::Camera node anywhere in my scene graph and it would act much like
> my nodes above. I either didn't set the correct options or this is
> not a
> valid use of the Camera class.
>
> I've also tried attaching a camera to the root node (more properly
> I am
> attaching it to the Scene data for my view). That works great for
> things
> like a HUD, but that doesn't quite seem right in this particular case.
> For what it's worth "this particular case" is where I would like
> to put
> a viewport size quad over the viewport, which would cover effectively
> cover up my ancestors but allow my children to be seen (I also thought
> an osg::Billboard is what I might want, but that didn't seem to be
> right
> either). However, I've also wanted to do this same thing for sky
> effects, etc. but have found clunky workarounds for most of the
> other cases.
>
> I then got to looking at the Drawable class and thought that
> overloading
> drawImplementation would be the best thing to do. However, that
> doesn't
> seem quite right. Perhaps it is after all.
>
> So, I'm sure that I can do this in osg, I'm just not sure how. I'm
> still
> adjust my mind to the osg paradigm, so I've probably overlooked
> something obvious, although I didn't see it when I search the mailing
> list. In essence, I want to be able to do the same type of inline
> projection I did before. What am I missing?
>
> Thank you
> John Cummings
> _______________________________________________
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> <mailto:[email protected]>
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>
>
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