I actually made this project about 2 months ago, but I forgot to upload it lol. (This project is glitched. Making new version soon!) Limitations / bugs: Has a limit of drawing about 479 lines before stopping the rendering process, instead of drawing what is actually shown of the wall. If you walk at some angles, some of the wall may get a slight delay. Not quite sure how to fix that If you rotate close to the wall or move close to the wall, it seems to snap at weird positions. Textures that have new color going vertically are going to slow down the frame rate because Scratch is not fast with the pen tool. :| This only works with one wall. As to why, I have absolutely no clue. I'm guessing it may have to do that some variable that is not getting reset properly, but I don't know.
Thanks to @AniMaJr for making the original portal renderer.