Pickpoints, edit front only?

hi all,
i attach my question in this post because it’s “related”. I have a patch in that i’m inside a sphere, and i can look around (like a quicktime vr). and like a qtvr i have some hotspot, so i used pickpoints(3dvector) for selecting this hotspots distributed around the sphere when the mouse rollover. now, that’s the problem. i noticed that i “rollover” the point when they are behind me too. so i need to use the “edit front only” feature. i explored the mesheditor patch, but i noticed that the visiblepoints(3d), because of it’s purpouses, needs the mesh.
In my case i don’t have a mesh, but only a spread of xyz vectors that represent the points in the space. so, how can i know the hotspots is in front of camera, for picking only that?