The Isadora Software Development Kit (SDK) allows you to write your own Isadora modules in C or C++.
There is no documentation for the SDK at this time, but the example projects are heavily commented. For instance, if you want to make a video processing plugin, you need only to modify a few items in the example plugin (which are clearly marked) and then write the code to process the video.
The Macintosh SDK includes a brief set of instructions to help you begin and several XCode projects with example plugins.
The Windows SDK includes a “Wizard” for creating a basic plugin, a brief set of instructions to help you begin, and several projects for Visual Studio 2008 with example plugins. (We are in the process of updating these files for Visual Studio 2010. This should be available by mid-May 2012 at the latest Please visit this page for updates.)