XNA Content Pipeline Explained

Posted July 17, 2011

While investigating XNA lately, I’ve gotten stuck learning about the content pipeline a few times. This is a short post to share some good links that I’ve found in trying to make sense of it, and also explain it in a less jargon filled way than the Microsoft docs. The system was a bit confusing at first because it’s terminology isn’t what I’ve heard making games before.

In usual game development we make tools to translate files, like jpg images, into a game readable format. Then we create what we call a “build system” to trigger those tools on the right files with the right parameters. The XNA content pipeline serves the same purpose as a build system. Instead of custom tools it uses C# code and the build system is hidden from view unless you know where to look.

The RPG Starter Kit is an excellent resource when trying to set up your first project. You can see how they organized things into a main project for logic, a library project for data types that will be used in the game, and a project for content building. You have to split it up or you’ll get a circular reference, as in a project referencing a project that references it. You can also see how to use xml in the content pipeline, which is the simplest way to start storing things like items and character information. A good tutorial on using xml like this is found here, and a video about it here. They may help make sense of whats going on in the starter kit.

The content pipeline is really flexible once you figure out how its organized so lets look at that with an example. Data first goes through a “Content Importer” which reads the file into a normal C# type, like a DataSet in the case of the previous link. Then that goes through a “Content Processor” which creates an instance of the in game data type and fills it with data, in this case the treasure class. Next the in game type goes to the “Content Writer”, which finally writes it out to a binary xnb file. When your game runs, you call Content.Load to load the data. It’s loaded through a “Content Reader” that reads in the binary file completing the pipeline. A diagram and more technical sounding descriptions can be found here.

Depending on your situation you may not need to write much code. The content pipeline will create readers and writers for you based on reflection in the later versions. The pipeline already comes with a few importers and processors so unless you want to read in an unsupported file type (like a spreadsheet) you won’t have to create more. Writing this has definitely made more sense of it for me, and hopefully it’s helped you too.