Quartz Composer

Quartz Composer is a node-based visual programming language provided as part of the Xcode development environment in macOS for processing and rendering graphical data. Quartz Composer uses OpenGL (including GLSL), OpenCL (only in Mac OS X Snow Leopard and later), , Core Video, JavaScript, and other technologies to create an API and a developer tool around a simple visual programming paradigm. Apple has embedded Quartz technologies deeply into the operating system. Compositions created in Quartz Composer can be played standalone in any QuickTime-aware application (although only on Mac OS X Tiger and later), as a system Screen Saver, as an iTunes Visualizer, from inside the Quartz Composer application, or can be embedded into a Cocoa or Carbon application via supplied user interface widgets. While Quartz Composer is included with the iPhone SDK, there is no way of running Quartz Compositions on iOS devices. Starting in macOS Catalina, the Quartz Composer framework has been deprecated, although it is still present for compatibility. Quartz programming through Quartz Composer works by implementing and connecting patches. Similar to routines in traditional programming languages, patches are base processing units. They execute and produce a result. For better performance, patch execution follows a lazy evaluation approach, meaning that patches are only executed when their output is needed. There are three types of patches: Consumers, Processors, and External Input patches that can receive and output mouse clicks, scrolls, and movements; MIDI and audio; keyboard; or other movements. A collection of patches can be melded into one, called a macro. Macros can be nested and their subroutines also edited. To control the order of rendering, each renderer is assigned a layer, indicated in its upper-right corner. Layers are rendered sequentially, lowest to highest. Renderers can be enabled or disabled, essentially turning on or off that particular layer. Turning off unused layers often results in better performance, since fewer upstream patches need to be evaluated.