A scene graph consists of one or more nodes, each of which represents a geometry, property, or grouping object. Hierarchical scenes are created by adding nodes as children of grouping nodes, resulting in a directed acyclic graph.
![[Note]](../images/note.jpg) | |
Note: Although Inventor nodes are organized into graphs, Inventor has no enforced policy on how the scene database is organized. You could, for example, create your own nodes that are organized into structures that are not graphs. (See The Inventor Toolmaker for more information on extending the Open Inventor toolkit.) |
Figure 3.1, “ An Inventor Database ” shows a simple database containing five scene graphs. The top node of a scene graph is called a root node (nodes A through E). Notice how node H is connected to two different parent nodes. This is called shared instancing. Also note that node E is not connected to any other node in the database. Usually this is a temporary state, and the node is attached to other nodes as you build the scene graph.