Just created a cutoutshader:

There is a cube model with the attached cutout material. It clears the given space, so the background becomes visible(by still respecting objects in front of it).

The cool thing is:
The hole, while invisible, is still color encoded. A postprocessingshader can easylly detect it:


by checking for the colorencoding, its possible to differenciate the holes during the postprocessing. Above hole just filled with red.

EDIT: i had the idea for this cutoutshader after kartoffel explained is paradox demo.

Greetings
Rackscha