This a prototype for an upcoming game. The blue border shows the portal, press e to place where the portal exits too. Currently you can only go through one portal, the green thing is the player. If it is slow, turn up the res variable, or go to the turbowarp: turbowarp.org/957668334 Or if you would like a special feature use this link instead: https://experiments.turbowarp.org/pointerlock/957668334/ and then press P after you click the green flag.
This is @griffpatch 3d engine, but I added the portal