Figure 15.15 A bar twisted using Y-axis, cross-section rotation at each spine coordinate.
15fig15.wrl	Click on the image to view the VRML scene.

#VRML V2.0 utf8
# The VRML 2.0 Sourcebook
# Copyright (c) 1997
# Andrea L. Ames, David R. Nadeau, and John L. Moreland
Shape {
    appearance Appearance {
        material Material {
            diffuseColor 1.0 0.5 0.0
        }
    }
    geometry Extrusion {
        creaseAngle 0.785
        crossSection [
        # Square
            -1.0  1.0,   1.0  1.0,
             1.0 -1.0,  -1.0 -1.0,
            -1.0  1.0
        ]
        spine [
        # Straight-line
            0.0 0.0 0.0,
            0.0 0.5 0.0,
            0.0 1.0 0.0,
            0.0 1.5 0.0,
            0.0 2.0 0.0,
            0.0 2.5 0.0,
            0.0 3.0 0.0,
            0.0 3.5 0.0,
            0.0 4.0 0.0
        ]
        orientation [
            0.0 1.0 0.0 0.0,
            0.0 1.0 0.0 0.175,
            0.0 1.0 0.0 0.349,
            0.0 1.0 0.0 0.524,
            0.0 1.0 0.0 0.698,
            0.0 1.0 0.0 0.873,
            0.0 1.0 0.0 1.047,
            0.0 1.0 0.0 1.222,
            0.0 1.0 0.0 1.396,
        ]
    }
}