Is there any way to get a primitive square to be invisible in a scene while also making everything behind it invisible too? So if this primitive covered half a scene for example, only half of it would render and the half covered would be invisible.

A pretty horrible description of what I'm after, I know. Truth be known, I don't know if such a thing is even possible in Poser.

my method would be to cut the render in half in APS, but maybe one of them can supply the node settings for bagginsbill's artistic lens that would prevent anything behind it from appearing in render.  the syntax of your request may be confusing, but bill created his lens (in part) for those who may not wish to do postwork in APS.

For that effect I render twice, putting what I want partly vidible on its own. Then load the two layers in a paint program , and delete part of the top layer.  You can do the same thing with more layers to get a mixed textured/wireframe effect.

Thank you both for your suggestions, I'll give them both a try.