It is a lock-FPS mechanism (no frame skip, but rather slo-mo mode on iwbtg).
Alright, that shouldn't pose any issues then. I'd like to see a delta-time implementation some day, but for now, that remains an interesting thought experiment (Although I think Starz0r had something along those lines, I should check that out). When your game comes out we'll see how well you did matching the physics!
This means I am not using jogl or lwjgl, and I have no experience with those anyway. From what I've heard you can't draw directly to the screen with jogl and I'm really unsure about how that works. All I can say is that if I were to include jogl or lwjgl I would (probably?) have to rewrite a lot of the code.
Well if Swing is doing well enough for you, why fix what ain't broken
Certainly go for getting everything to work first. OpenGL is pretty complicated, it's very difficult to make anything resembling a "hello world" example using it, so it requires a lot of warm-up time as you learn how to interface with the GPU. I would say that "you've got the proper interfaces, e.g. Drawable, set up to abstract the actual code away so you only have to update it in one spot", but it's never as simple as that is it
You do have everything structured well though, very good to keep the responsibilities separated like that so that a game tells the room to draw, the room tells the objects/tiles to draw, and the objects/tiles do the actual drawing. That said, it would certainly require some effort to replace the graphics layer. Might be an interesting thing to fork and add one day, if the code ever ends up on github or the like!
One thing I'd really like to see is your collision handler code. Are you doing pixel-perfect collisions, or using polygonal bounding boxes? Did you write an algorithm based off the Separating Axes Theorem? That was the fastest, most functional thing I found when I was researching the subject at the time, would be interested to hear if you went a different way.
PS. I'll be more impressed when you can have those lines move around to specific points of origin and go through certain points and have different slopes :-). Also collisions!
This is why I can never get any work done
https://i.gyazo.com/47c0c28177fcd9a74961cd180d4d04ac.mp4