1. A carrier medium comprising program instructions for creating a scene graph, wherein the program instructions are executable to implement: creating a data flow diagram in response to input, wherein said creating comprises: displaying a first plurality of nodes on a display, wherein each of the plurality of nodes is executable to create at least a portion of the scene graph; connecting the first plurality of nodes to create the data flow diagram, wherein the first plurality of nodes are connected to specify data flow among the plurality of nodes; and executing the data flow diagram, wherein said executing creates the scene graph; wherein the scene graph specifies a plurality of objects and relationships between the objects, and wherein the scene graph is usable in rendering a graphical image of the plurality of objects.