I'm writing a 2D room-based* platformer using XNA, and I'm trying to figure out the best way to load resources based on what the current map requires. I've yet to find a tutorial that goes this far--they usually load one small tileset and call it good enough--and a night of googling hasn't turned up anything particularly useful.

Basically, I need to (want to) dispose of the loaded tileset/textures and load just the ones the next map requests at every transition (ideally, I'll check if they're actually different first), without killing off the more universal textures (player sprites, etc.). I've seen a few forum posts saying the best way to do this is to create a second instance of ContentManager, but they never go into detail on how to do this correctly.

Currently, my XML map files each contain a string with the name of the tileset they're supposed to use, along with the names of all the background/parallax images for the map. I was planning on having my XmlReader method load the textures as their names were read, but then I realized I knew neither how to instantiate the second ContentManager, nor where to instantiate it--i.e., should it be in the MapFactory class that's loading the map, or in the static LevelManager that's calling the MapFactory (passing the new ContentManager as a parameter to the MapFactory, along with the name of the desired map)?

Any advice would be greatly appreciated, including "that's a terrible way to do that," if necessary. This is my first attempt at a game with more than a single map, after all.

*Ex. Castlevania, Metroid, but simpler (for now). I'd like to implement constant streaming eventually (chunks loaded as they are approached), but I want to get this part down first.

I don't see why you would need a second ContentManager, just use the one you already have and pass it into the class / method that reads the XML.

I don't see why you would need a second ContentManager, just use the one you already have and pass it into the class / method that reads the XML.

Everything I've read has suggested that unloading specific items from the ContentManager is either impossible or ill-advised, depending upon how one tries to do it, and that you're better off making extra instances for any assets that you'll want to load/unload during gameplay.

I need to kill off just the assets used by the current map when that map is exited, otherwise I'll end up with multiple unused tilesets and large background images loaded when they don't need to be. Unloading the entire main ContentManager on every new map and loading the map's requested assets would solve that, but it would result in needing to reload all the universal assets (map-independent, i.e. player sprites, menu images, etc.) on every map as well, which just seems really sloppy.

Everything I've read has suggested that unloading specific items from the ContentManager is either impossible or ill-advised, depending upon how one tries to do it, and that you're better off making extra instances for any assets that you'll want to load/unload during gameplay.

So what's wrong with having a separate ContentManager in say, your "Map" class? It won't interfere with your main ContentManager.

So what's wrong with having a separate ContentManager in say, your "Map" class? It won't interfere with your main ContentManager.

That's exactly what I was asking how to do. I couldn't figure out what to use for the first parameter in the new ContentManager's constructor--couldn't get access to Game.Services. I eventually figured out I could instantiate the new one in my Game class using this.Services (I'd been trying to do it in the LevelManager or the MapFactory class); I'll just have to pass it through to the classes that need it via dependency injection.