How the screen transitions work

Hello everyone !

   During the voting phase of the jam this game took part in, I saw multiple people playing said game, and I noticed quite a few where wondering why the screen transitions were the way they are.

There are multiple reasons as to why it is this way :
    The first is that, being my first gameboy game, I have no idea on how to make continuous scrolling between two rooms, and still make the whole thing clean and aligned in the end. 

    The second, which came after, was that this way it was possible to load entire tilesets and palettes during the transitions (and as such, it could allow for very diverse areas, though it wasn't used that much in the demo, mainly due to time constraints). 

    On the other hand this made fading out the room you're leaving obligatory, due to the fact that graphics and palettes could change drastically between the two rooms, and the room you're leaving would be very, very ugly during the transition, as a result. I still made it so that the new room scrolled in the direction you where going, so as to keep the world a bit more "together", rather than it feeling like a simple collection of rooms.

   Scrolling in the rooms was also a bit of a problem, though not as much as trying to transition continuously between two rooms. You see, the gameboy tilemap is bigger than the screen, but not big enough to fit two screens in width nor in height.

(This is the entire gameboy tilemap, as you can see, a single screen takes quite a lot of space, and you can't quite fit in 2 screens at once)

  Thus you cannot just load the entire room at once and scroll it in, as part of it would be visible before it scrolled in. My solution was to offset the camera so that it was at the very bottom of the soon-to-be-loaded room, and load said room row by row, scrolling the camera with each new row loaded in.


(On the left is a screenshot of the game during a transition, and on the right here's how the tilemap looks on that same frame. You can see here that the entire room isn't loaded yet)

This is why when you move from room to room, it fades out, before scrolling in the new room.

If you have other questions on how the game works, feel free to post a comment with your question, and I'll try to explain as best as I can!

Thank you for reading, and see you next time!
Geek_Joystick