An endCap with a counterclockwise ordering shall have a normal along the positive Y-axis. For instance, a circular crossSection with counter-clockwise ordering and the default spine form a cylinder. With solid TRUE and ccw TRUE, the cylinder is visible from the outside. See Figure 3-22 for several examples of the Extrusion node. The first example illustrates the effect of the scale field, the second example illustrates the rotation field, the third example illustrates the spine field, and the fourth example illustrates the combined effects of these fields.
Extrusions are also much more convenient than IndexedFaceSet.
Because implementations know the topology of an extrusion, normals are more easily generated. Texture coordinates are also easily generated and cannot be specified. You can use a TextureTransform node to modify the generated coordinates, but must use an IndexedFaceSet if you want complete control over texture map application. The second Extrusion node defines a beveled, cookie cutter object.