26. In the computer graphics system of claim 24 , the further improvement in which at least one type of shader node is of a photon shader node type, the further improvement in which the pre-processor is configured to perform the pre-processing operation if the at least one shader node is of the photon shader node type to control the paths of photons in the scene and the characteristics of interaction of photons with surfaces of objects in the scene.
24. 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 computer graphics system comprising (A) a pre-processor configured to determine whether the at least one instantiated phenomenon requires a pre-processing operation in connection with the representation, and, if so, performing the pre-processing operation to generate a pre-processed representation of the scene, and (B) a renderer configured to generate a rendered image from the pre-processed representation of the scene, the improvement comprising: a metanode environment operable for the creation of metanodes, the metanodes comprising component shaders that can be combined 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, and a software language useable by a human operator and operable to manage the metanode environment, implement shaders and unify discrete shading applications, the software language configurable as a superset of a plurality of selected shader languages for selected hardware platforms, and operable to enable a compiler function to generate, from a single, re-usable description of a phenomenon expressed in the software language, optimized software code for a selected hardware platform in a selected shader language.