For the purpose of my hypothetical PPy experiment, I thought I might cull by getting the distances of the points from a plane defined by the camera position, then favor the closest one which fits the proper clicked coordinates in the world to screen list.

So far the only point-within-volume function I've been able to grasp is just checking whether something is within a bounding box, with the bbox having flat sides on x,y,z.  It's a drag being math-dumb....

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Cage can be an opinionated jerk who posts without thinking.  He apologizes for this.  He's honestly not trying to be a turkeyhead.

Cage had some freebies, compatible with Poser 11 and below.  His Python scripts were saved at archive.org, along with the rest of the Morphography site, where they were hosted.