Hello monkeys 
!
I’ll start a series of 2D game development and it’ll be very useful to have a 2D Scene Composer. I didn’t found anyone, so I would like to know if there is a plugin already, or if may I try to do one.
I’m planning something like 2D editor of Unity, where you can add sprites, backgrounds, effects and animations. Yes, this is a lot of work to do, but maybe I finish it.
EDIT: After reading source of Scene Composer: Maybe I finish it on 2018 
Sounds like a good idea though theres engines more fitted for 2d game creation.
Theres the imagepainter plugin and somebody also did some kind of sprite “engine” but I think its not available as plugin. Maybe you can work off of that.
As for the SC source, you’d basically implement a completely new Scene Composer so you’ll get into it 
Another question: To make the scene view of 2d editor, what you think it’s better:
a) use com.jme3.core.scene.SceneApplication;
b) extend com.jme3.core.scene.SceneApplication;
c) create my own Scene2DApplication based on Application;
I ask it because after reading sceneview source, it’s a jme3 application that runs on canvas on top of JPanel, so I don’t know what is better or fastest or best pratice…
You grab the scene (the main GL window) for yourself, probably open another TopComponent (a window like the one the Terrain and Scene Editor open at the bottom) and do what you need to do:
http://wiki.jmonkeyengine.org/doku.php/sdk:development:scene
It’s not integrated with the scene composer, but you should poke @ndebruyn about his Galago framework.
In the current scene composer you can switch the camera view to orthogonal, maybe just locking the camera Z position and locking X&Y rotation the can do the trick
What i’m planning to do it’s not about only placing objects on scene. I would like to do more a bit more, but to be honest, I don’t know what I’ll be capable of.
At this moment, i’m creating a algorithm to auto split spritesheet, like Unity3D.