1. In a computer graphics system for generating an image of a scene from a representation to which at least one instantiated phenomenon has been attached, the instantiated phenomenon comprising an encapsulated shader DAG comprising at least one shader node, the improvement comprising: a metanode environment operable for the creation of metanodes, the metanodes comprising component shaders that can be combined in networks to build more complex shaders, and a graphical user interface (GUI) in communication with the metanode environment and operable to manage the metanode environment to enable a user to construct shader graphs and phenomena using the metanode environment.