Looking inside a room by defining an inner volume

[simonbethke]

When dealing with enclosed gaussian scenes it sometimes is hard to look inside as this either requires hiding or deleting certain gaussians or placing the camera inside.
This feature suggestion would make looking inside such rooms much more easy.

This sketch hows the basic idea:

1. Looking into an enclosed room is not possible if the camera is outside
2. The inner volume is rougthly defined. For example with an axis aligned bounding box as shown in the sketch
3. What the camera should now do is, calculating the screenspace depthmap of the bounding box and cull all splats that are in front of that box.