Figure 27.1 A dungeon door that slides open and closed based on visibility.
27fig01.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 [
        NavigationInfo { headlight FALSE },
    # Room
        Inline { url "droom.wrl" },
    # Wall
        Transform {
            translation 0.0 0.0 -5.0
            children Inline { url "dwall2.wrl" }
        },
    # Left and right door panels
        Transform {
            translation 0.0 0.0 -4.95
            children [
                DEF LeftDoor Transform {
                    children Transform {
                        translation -0.75 0.0 0.0
                        children DEF Door Inline { url "ddoor.wrl" }
                    }
                },
                DEF RightDoor Transform {
                    children Transform {
                        translation 0.75 0.0 0.0
                        children USE Door
                    }
                },
            # Visibility Sensor
                DEF DoorSense VisibilitySensor {
                    center 0.0 1.75 0.0
                    size 3.0 2.5 1.0
                }
            ]
        },
    # Sounds
        Sound {
            source DEF OpenSound AudioClip { url "clunk1.wav" }
            minFront 20.0 minBack 20.0
            maxFront 60.0 maxBack 60.0
        },
        Sound {
            source DEF CloseSound AudioClip { url "clunk1.wav" }
            minFront 20.0 minBack 20.0
            maxFront 60.0 maxBack 60.0
        },
    # Animation clocks
        DEF OpenClock TimeSensor {
            cycleInterval 0.5
        },
        DEF CloseClock TimeSensor {
            cycleInterval 0.5
        },
    # Animation paths for the left and right doors
        DEF LeftOpen PositionInterpolator {
            key [ 0.0, 1.0 ]
            keyValue [ 0.0 0.0 0.0, -1.3 0.0 0.0 ]
        },
        DEF LeftClose PositionInterpolator {
            key [ 0.0, 1.0 ]
            keyValue [ -1.3 0.0 0.0, 0.0 0.0 0.0 ]
        },
        DEF RightOpen PositionInterpolator {
            key [ 0.0, 1.0 ]
            keyValue [ 0.0 0.0 0.0, 1.3 0.0 0.0 ]
        },
        DEF RightClose PositionInterpolator {
            key [ 0.0, 1.0 ]
            keyValue [ 1.3 0.0 0.0, 0.0 0.0 0.0 ]
        }
    ]
}
ROUTE DoorSense.enterTime         TO OpenSound.set_startTime
ROUTE DoorSense.exitTime          TO OpenSound.set_stopTime
ROUTE DoorSense.enterTime         TO OpenClock.set_startTime
ROUTE DoorSense.exitTime          TO OpenClock.set_stopTime

ROUTE DoorSense.exitTime          TO CloseSound.set_startTime
ROUTE DoorSense.enterTime         TO CloseSound.set_stopTime
ROUTE DoorSense.exitTime          TO CloseClock.set_startTime
ROUTE DoorSense.enterTime         TO CloseClock.set_stopTime

ROUTE OpenClock.fraction_changed  TO LeftOpen.set_fraction
ROUTE OpenClock.fraction_changed  TO RightOpen.set_fraction
ROUTE CloseClock.fraction_changed TO LeftClose.set_fraction
ROUTE CloseClock.fraction_changed TO RightClose.set_fraction

ROUTE LeftOpen.value_changed      TO LeftDoor.set_translation
ROUTE LeftClose.value_changed     TO LeftDoor.set_translation
ROUTE RightOpen.value_changed     TO RightDoor.set_translation
ROUTE RightClose.value_changed    TO RightDoor.set_translation