HI J.P,

The OverlayNode does use a StateFrustum to cull the overlay texture
from being applied behind the projection center, but it only works at
the geometry level, so if any of the bounding box of object intersects
this frustum then the overaly texture is applied.  If you geometry
chunks are small enough then it should cull the texture behind the
projection.  Making two hemispheres won't be fine grained enough to
take advantage of this culling.

The other solution is right a shader that disgards the overlay texture
when the r texture coordinate is negative, or to use a third texture
aligned along the r coordinate to do this for you.


Robert.


On 5/31/06, J.P. Delport <[EMAIL PROTECTED]> wrote:
Hi,

I am using the osgSim::OverlayNode with an earth model attached as the
subgraph. I have a local coordinate system with the 0 position at some
point on the planet. When I generate an overlay, it appears in the
position that I want, but also on the opposite side of the globe.

Is there a way to prevent either texture coordinate creation for the far
side or to prevent the texture application to the far side?

I have though about splitting the globe in two, but the zero position is
not fixed in the application.

Any pointers appreciated.

rgds
jp

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