Endless/infinite/mirrored level

Hello everyone. I need help with a thing, which correct name is unknown for me :slight_smile: So I’ll try to explain, whot I’m actually going to achieve: I have made large world (~20 000 square kilometers) and the world is built with help of world composition, and its square. The world itself working like a charm, but now I want to make it endless, like… planet. So if the player will reach level border, he will see oppositeside of the level, and if he try to walk further - he will be transitioned to the opposite side of world. How can i achieve this effect, or maybe someone know how the effect is called?

One additional question: my game is based on physics, so physics must be as presice as possible at moment of the transition… and the transition must be seamless…

Just tried the “Portal” technique, this is not goig to work, as the video memory consumption is more than 500Mb. Maybe there is a way to change world compositions level position, so the level will be moving with player?