is what I could get from masking the postprocess to a sphere, which can easily adapted to a box mask, thou for complex shapes you will still need to go for a Distance Field solution, which unfortunetely takes more time.
The video contains a small level, wich the and an island, the dome inside the and I am showing a glass material for the dome and the changes needed into the Postprocessing material for the mask and some hints on how to expand the concept.
The video: FUxQAv5FIuM
Anyone making useful stuff for project, I invite you all to “share” once in a while, makes sense since project takes a long time to accomplish and its been given for FREE.