[osg-users] Intersection with 2d plane embedded in 3d

[Steve Hardy]

Hi,

Is there any way to create a "virtual infinite" quad (i.e. plane) that satisfies the intersection test, but without being rendered itself?

Or is there a good way of converting screen coordinates to "local" embedded 2d model coordinates?

Motivation:

My application has line strips and other 'skinny' geometry which are all defined with a zero Z value hence are basically 2d, but are embedded in a 3d model under some DOF transforms.  I wish to find the 2d local coordinate corresponding to a mouse click.

I can do this by defining a quad then using a line intersector, but if I hide the quad behind, say, a switch node which is turned off, then the intersection does not work.  Maybe that's because I don't know how to restrict computeIntersections() to start at a particular node in the tree.  Anyway, a quad needs a particular size, but I really want the plane intersection, not just part of it.

Ultimately, though, I am happy to define a big quad provided I can avoid rendering it.

Thank you!

Cheers,
Steve

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