Limit plane intersection to the positive area

Hi All,

Given a plane in xyz, is there a way to restrict its validity/use to only the 'positive' halfs?

IE: I have a radial setout of gridline planes across 180 deg. This is fine; however the end point planes technically occupy the same space/plane, just in opposite directions, meaning any intersections occur twice for both planes. But this would not be the case if I can restrict intersections to only occur in the positive space - ie, by the time the plane vectors come back around, their X direction is different and therefore would only register what was in the positive direction away from the center point.

Thanks,

-BC