Hi Anton,
How can the skybox ever get behind the camera?
Usually a skybox is rendered relative to the camera, so it stays around
the camera.
Also, why can't you simply render the "skybox" first, not writing the
depth buffer.
This will put everything to the background as you intend.
Maybe I don't understand your vertex-shader approach, but I don't see
any need to push vertices to the far plane, as filling the background
can be done prior to any depth related operations.
If you want to render your sky last you can invert the process, by
drawing fullscreen/skybox/shader-background with depth test on.
cheers
Sebastian
Robert,
thanks for the quick reply!
Summary:
if I use Geometry::setCullingActive(false), the geometry still gets culled if
behind the camera.
Detailed reply:
One approach would be to use Geometry::setInitialBound(BoundingBox&)...
This would not really help with the skybox: I move the vertices in the shader
to the far plane in camera space. I would have to make a BBox as large as any
potential scene the skybox should ever cover.
Wr.t bounding volume for the purpose of near/far calculations then you can
disable the computation of near/far values ...
I have done this for small scenes with static content, but I would rather just
disable culling for the skybox geometry and keep automatic near/far computation.
Which is why I tried this
Another approach is disable culling via Geometry::setCullingActive(false);
for the skybox geometry (a simple quad).
This works fine, as long as the initial bbox of the quad is in front of the
camera (but outside the frustum), but the geometry still gets culled as soon as
it gets behind the camera.
Summary:
My patch assures that nodes with node.setCullingActive(false) are not culled,
even when they lie behind the camera. I would presume this the expected
behavior when you turn of culling. But since I am still a newbie to OSG,
especially the internals, I would really like to know if my fix breaks things
or if there is a better way for getting geometry to render under all
circumstances.
best,
Tony
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http://forum.openscenegraph.org/viewtopic.php?p=55946#55946
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