On 11/6/06, Paul Martz <[EMAIL PROTECTED]> wrote:
Let me take a crack at this; if I'm wrong, I'd like to be publicly shamed so
that the correct answer will be engraved into my head.
My understanding is that Producer::Camera (and CameraGroup) is/are excellent
for multithreaded rendering (with the traversal in a separate thread) and
also for rendering to multiple displays (each with their own graphics card).
osg::CameraNode, on the other hand, is well-suited for render-to-texture
applications in which you'd like the offscreen rendering to be automatically
culled if the results are not needed for the final rendered image.
The big difference is probably that Producer::Camera/CameraGroup are
viewer level cameras that you application can use for rendering
scenes. You can also use them for RTT but they remain at the
application level.
The osg::CameraNode is a node in the scene graph, but it also can be
used at the application level. CameraNode can be used for out of the
window views like a Producer::Camera as well as RTT work.
CameraNode's main usage so far has been for RTT, as this was their
initial reason for their existance. CameraNode's have good support
for automatically select RTT implementations - i..e if FBO's isn't
available then it'll transparently fallback to using Pbufer etc.
There is also value in have a Camera part of the scene graph, and this
is ability to cull them, or dynamically load them at runtime, for
instance is you move into a room then needs a multipass RTT effect the
OSG backend will automatically set up all the required support for the
RTT behind the scenes - your application itself doesn't need to know
about all these complex rendering techniques. Such techniques can
also be saved along with the scene graph, so you need to customise you
app for specific effects in mind.
The new osgViewer library takes the osg::CameraNode node into the
domain of the application, out of window view control. It doesn't do
threading like Producer camera's do.
Robert.
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