Brief introduction to Quartz Composer

Apple makes software that's easy on the eyes. Each window has a subtle drop shadow, text is attractively anti-aliased, and effects animate smoothly and elegantly. For the most part, what you see on your screen is put there by Quartz, Apple's technology that renders graphics, text, and video. Quartz stretches a window that's being minimized to the dock, and shrinks and shifts windows when you activate Expose. For a quick demonstration of how powerful it is, play a video in Quicktime and then minimize the window while holding Shift on your keyboard. With the effect in slow motion, notice how the video plays smoothly, even while it is being stretched like silly putty.

Apple has provided a free application to play with the technology behind effects like this. It is called Quartz Composer, and you can get it by installing Apple's Developer Tools from your Mac OS X install disc. Quartz Composer is a visual programming language (similar to Max/MSP, for you audio folks), meaning that you connect boxes (called "patches") to each other. Patches collect data (sound from a microphone, an RSS feed, video from an iSight camera) and process it by performing mathematical or other operations. Once you've created a Quartz Composer composition, you can save it as a .qtz file to share with anybody with OS X Tiger or Leopard.

Quartz Composer compositions are procedural, meaning that your computer is generating everything you see in real-time. Unlike movies, they take up very little space and can be designed to loop infinitely. For an example of a Quartz Composer composition in action, check out the "RSS Visualizer" Screen Saver on your Mac. Other resources and examples on the web include Apple's programming guide and this collection of very clever samples. Happy composing!