I'm trying to come up with a general concept for transitions, without having to include any specific code inside the actual scene. In all the samples I've seen so far the scenes handle that stuff themselves. Like a fade in/out, where the scenes have to adjust their draw method, for the correct transparency. But not only would this be annoying to have in every scene, with multiple kinds of transitions you'd get cluttered code pretty fast.
So I've been thinking. The only way I could come up with to support this, and more complicated transitions, without handling it in the scene itself, are render targets for each scene. The render target would be set from the scene manager before calling the draw method. After draw the render target would get reset to the render target of the manager, and the scene's texture would get drawn with information about the current transition. Without clearing the manager texture more scenes would follow, if more have to be drawn. This way you could do pretty much anything (transition wise), the scenes would be completely independent of each other, and you wouldn't need a single line of transition code in the actual scenes. (For reference, there are various transition types I'd like to be able to do. Not only fades, but also shader effects, moving one scene in while the current one is "pushed away", etc., involving one or multiple scenes.)
Well, that's my theory. Here comes my question: Does this sound like a viable plan? Is this the way to go? I've read about performance problems when switching rendering targets too frequently, and other problems, which is the main reason I'm hesitating to implement this. But so far I couldn't think of or find a better method. Although I think it shouldn't make a difference, for the moment I only care about 2D (mentioned just in case).
That, in general is a sound approach, but beware render target switching costs. Also, if each scene were to be animated at the time of transition, you'd be rendering two scenes at the same time into two different rendertargets and then compositing the results on screen.