Figure 30.2 A filter used to make a group of radio buttons that select among backgrounds.
30fig02.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
Group {
    children [
    # Bindable Backgrounds (cyan, red, blue)
        DEF Back1 Background {
            skyColor    [ 0.0 0.2 0.7,  0.0 0.5 1.0,  1.0 1.0 1.0 ]
            skyAngle    [ 1.309, 1.571 ]
            groundColor [ 0.1 0.1 0.0,  0.4 0.25 0.2,  0.6 0.6 0.6 ]
            groundAngle [ 1.309, 1.571 ]
        },
        DEF Back2 Background {
            skyColor    [ 1.0 0.0 0.0,  1.0 0.4 0.0,  1.0 1.0 0.0 ]
            skyAngle    [ 1.309, 1.571 ]
            groundColor [ 0.1 0.1 0.0,  0.5 0.25 0.2,  0.6 0.6 0.2 ]
            groundAngle [ 1.309, 1.571 ]
        },
        DEF Back3 Background {
            skyColor    [ 1.0 0.0 0.8,  0.5 0.0 0.8,  0.0 0.0 0.8 ]
            skyAngle    [ 1.309, 1.571 ]
            groundColor [ 0.0 0.0 0.1,  0.0 0.1 0.3,  0.3 0.3 0.6 ]
            groundAngle [ 1.309, 1.571 ]
        },
    # Shapes to act as buttons (cyan, red, blue)
        Transform { translation -3.0 0.0 0.0
            children [
                Shape {
                    appearance Appearance {
                        material Material {
                            diffuseColor 0.0 0.5 0.8
                        }
                    }
                    geometry Box { }
                },
                DEF BackButton1 TouchSensor { }
            ]
        },
        Group {
            children [
                Shape {
                    appearance Appearance {
                        material Material {
                            diffuseColor 1.0 0.3 0.3
                        }
                    }
                    geometry Sphere { }
                },
                DEF BackButton2 TouchSensor { }
            ]
        },
        Transform { translation 3.0 0.0 0.0
            children [
                Shape {
                    appearance Appearance {
                        material Material {
                            diffuseColor 0.2 0.2 0.8
                        }
                    }
                    geometry Cone { }
                },
                DEF BackButton3 TouchSensor { }
            ]
        },
    # Scripts
        DEF Filter1 Script {
            url "javascript:
                function set_boolean( bool, eventTime ) {
                    if ( bool == true ) { true_changed  = true; }
                    else                { false_changed = true; }
                }"
            eventIn  SFBool set_boolean
            eventOut SFBool true_changed
            eventOut SFBool false_changed
        },
        DEF Filter2 Script {
            url "javascript:
                function set_boolean( bool, eventTime ) {
                    if ( bool == true ) { true_changed  = true; }
                    else                { false_changed = true; }
                }"
            eventIn  SFBool set_boolean
            eventOut SFBool true_changed
            eventOut SFBool false_changed
        },
        DEF Filter3 Script {
            url "javascript:
                function set_boolean( bool, eventTime ) {
                    if ( bool == true ) { true_changed  = true; }
                    else                { false_changed = true; }
                }"
            eventIn  SFBool set_boolean
            eventOut SFBool true_changed
            eventOut SFBool false_changed
        },
    ]
}
ROUTE BackButton1.isActive TO Filter1.set_boolean
ROUTE BackButton2.isActive TO Filter2.set_boolean
ROUTE BackButton3.isActive TO Filter3.set_boolean
ROUTE Filter1.true_changed TO Back1.set_bind
ROUTE Filter2.true_changed TO Back2.set_bind
ROUTE Filter3.true_changed TO Back3.set_bind