I'm working on my first OSG project (so be gentle ;-) I'm using OSG
2.2 on OS X (Leopard).
I have a terrain in a .osga file, a skydome, and some .3ds models.
Everything loads fine, and I have a flight sequence working that takes
off and lands on an aircraft carrier.
There are lots of samples that made this part pretty easy to figure
out (just load and move objects around). I'm a little lost however as
to how OSG is handling the near and far clipping planes, and object
scale. Actually, OSG seems to be monkeying with these settings in a
manner that is probably a nice feature once I understand how to best
make use of it.
The terrain is really big, the skybox is really big, and the models
are really small in comparison. OSG seems to recomputing the near and
far clipping planes depending on the objects in view. For example, on
the deck of the carrier, all is well. If I turn so that the terrain is
also in view (off in the distance), the near clipping plane seems to
be changed and parts of the carrier disappear (the same happens with
the large skydome...) apparently to accommodate the display of the
much larger model that is now in view.
I did find an old message that says this:
Camera-
>setComputeNearFarMode(osgUtil::CullVisitor::DO_NOT_COMPUTE_NEAR_FAR);
prevents this... however, then I need a giant frustum to hold
everything and we all know what a bucket of z-fighting joy that
brings. It is not clear to me how to arrange these objects correctly
to make this "rescaling" of the scenes objects work correctly.
Currently, the terrain database, the skydome, and the ship models are
all hanging off the root of the scene graph with just a transform that
scales, translates and rotates them as necessary.
Is there a 'standardized' technique for this (it can't be that
unusual), none of the example programs seem to have this kind of
configuration.
Richard
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