Oliver C. wrote:
What about setting only one point at the beginning of the runway
and then calculating an angel between it and the normal of the billboard.
When the angel is > 90° or > - 90° the billboard is turned off when it is < 90° or < -90° then on.
We might need to do something like that. What I think might be a useful approach would be to add some sort of ssgDirectionalSelector where you provide a normal vector, a point, and a max angle. If the angle between the view point and the ssgDirectionSelctor point is within the specified angle, the child(ren?) are selected, otherwise they are skipped.
However, to make this work right, you'd need to do in per light (which would be *very* expensive) or for small groups of clustered lights (also probably expensive.) It would be nice to put the entire runway under a single node, but how do you pick the critical point? Too close to the start and the end lights will drop out too soon. Too close to the end and the front lights won't drop out soon enough.
I'm told there is a way to do this with shaders, but plib/ssg doesn't support shaders. :-(
Curt.
-- Curtis Olson http://www.flightgear.org/~curt HumanFIRST Program http://www.humanfirst.umn.edu/ FlightGear Project http://www.flightgear.org Unique text: 2f585eeea02e2c79d7b1d8c4963bae2d
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