Thank you for your critique.
We currently have no gravity so adding a jump would mean a lot of changes. We will probably have to fix the problems in another way.
I was not aware of the stancil buffer but I quickly looked into it and assume that our game would not be a good usecae for them. We use camera in the diffrent areas that are spacialy seperated and we are able to switch between. But I can see how the stencil buffer can be quite useful for simpler portal-like structures or illusions.