A DAG can be used for describing the structure of a whole scene.
A special type of node exists for this purpose: the scene graph node. It is connected to 3 other nodes: A list of child scene graph nodes, a list containing a transformation group and/or attribute groups, and finally to a list of geometric primitives (please see chapter 6 for more information about the different node types). Transformations accumulate on a path from the root of the scene to a leaf node.
The following example creates a polyline at two different locations, the structure of the resulting scene graph is shown in figure 3.2.
Example 3: (taken from: data/examples/scenenode1.dat (7.40))
line1 = POLYLINE2( ((0,0), (4,0)) ); trans1 = TRNSF3PT( (0,2), (1,2), (0,3) ); node1 = SCENENODE( (), (TRANSFORMS(trans1)), (line1) ); SCENEROOT = SCENENODE( (node1), (), (line1) );