In this branch of my fork https://github.com/MrAmericanMike/Wave-Function-Collapse/tree/better-tile-initialization

I created an "addTile" function. Basically what it does is push a new tile to the tiles array and if rotation is greater than 1 it will grab the last tile from the tiles array and push it as a new tile rotated 90o. (Notice we always rotate 90o as we are using the last tile from the array.