can't find package tcl3d 0.5.0
    while executing
"package require tcl3d 0.5.0"
    (in namespace eval "::request" script line 9)
    invoked from within
"namespace eval ::request $script"
    ("::try" body line 12)
OUTPUT BUFFER:
# Light.tcl
#
# Original C++ code by Peter Wraae Marino and Michael Bach Jensen.
# See www.osghelp.com for the original files.
#
# Modified for Tcl3D by Paul Obermeier 2010/03/20.
# See www.tcl3d.org for the Tcl3D extension.

package require tcl3d 0.5.0

# Font to be used in the Tk listbox.
set gDemo(listFont) {-family {Courier} -size 10}

# Window size.
set gDemo(winWidth)  640
set gDemo(winHeight) 480

# Determine the directory and filename of this script.
set gDemo(scriptFile) [info script]
set gDemo(scriptDir) [file dirname $gDemo(scriptFile)]

# Show errors occuring in the Togl callbacks.
proc bgerror { msg } {
    puts "Error: $msg\n\n$::errorInfo"
    tk_messageBox -icon error -type ok -message "Error: $msg\n\n$::errorInfo"
    ExitProg
}

# Print info message into widget a the bottom of the window.
proc PrintInfo { msg } {
    if { [winfo exists .fr.info] } {
        .fr.info configure -text $msg
    }
}

# Idle callback to redisplay the scene.
proc Animate {} {
    .fr.toglwin postredisplay
    set ::animateId [tcl3dAfterIdle Animate]
}

proc StartAnimation {} {
    if { ! [info exists ::animateId] } {
        Animate
    }
}

proc StopAnimation {} {
    if { [info exists ::animateId] } {
        after cancel $::animateId 
        unset ::animateId
    }
}

proc CreateCallback { toglwin } {
}

proc ReshapeCallback { toglwin { w -1 } { h -1 } } {
    set w [$toglwin width]
    set h [$toglwin height]

    # Propagate resize event to embedded OSG window.
    tcl3dOsgWindowResize $toglwin [tcl3dOsgGetOsgWin] $w $h
}

proc DisplayCallback { toglwin } {
    if { [viewer valid] } {
        viewer frame
    }
    $toglwin swapbuffers
}

proc Cleanup {} {
    uplevel #0 unset gDemo
    viewer -delete
}

proc ExitProg {} {
    exit
}

proc SaveOsgToFile {} {
    global gDemo

    set osgRoot [viewer getSceneData]
    set outFile [format "%s.osg" [file rootname $gDemo(scriptFile)]]
    # Create a name on the file system, if running from within a Starpack.
    set outFile [tcl3dGenExtName $outFile]
    puts "Saving scenegraph to file $outFile"

    if { ! [osgDB::writeNodeFile $osgRoot $outFile] } {
        puts "Failed to write scenegraph to file $outFile"
    }
}

proc CreateWidgets { osgwin } {
    global gDemo

    frame .fr
    pack .fr -expand 1 -fill both
    set toglwin .fr.toglwin
    togl $toglwin -width $gDemo(winWidth) -height $gDemo(winHeight) \
                  -double true -depth true -alpha true \
                  -createproc CreateCallback \
                  -reshapeproc ReshapeCallback \
                  -displayproc DisplayCallback 
    listbox .fr.usage -font $gDemo(listFont) -height 3
    label   .fr.info
    grid $toglwin   -row 0 -column 0 -sticky news
    grid .fr.usage  -row 1 -column 0 -sticky news
    grid .fr.info   -row 2 -column 0 -sticky news
    grid rowconfigure .fr 0 -weight 1
    grid columnconfigure .fr 0 -weight 1
    wm title . "Tcl3D demo: OsgHelp tutorial Light"

    wm protocol . WM_DELETE_WINDOW "ExitProg"
    bind .  "ExitProg"
    bind .       "SaveOsgToFile"

    # Propagate key and mouse events to embedded OSG window.
    bind .  "tcl3dOsgKeyPress $toglwin $osgwin %N"

    tcl3dOsgAddTrackballBindings $toglwin $osgwin

    .fr.usage insert end "Key-Escape Exit"
    .fr.usage insert end "Key-f      Save SceneGraph to file"
    .fr.usage insert end "Mouse      Trackball"

    .fr.usage configure -state disabled
}

#
# Start of tutorial specific code.
#

proc CreateSpheres { z } {
    osg::Geode geode

    geode addDrawable [osg::ShapeDrawable dr1 [osg::Sphere sph1 [osg::Vec3 c1 0.0 0.0 $z] 0.5]]
    geode addDrawable [osg::ShapeDrawable dr2 [osg::Sphere sph2 [osg::Vec3 c2 2.0 0.0 $z] 0.5]]
    geode addDrawable [osg::ShapeDrawable dr3 [osg::Sphere sph3 [osg::Vec3 c3 4.0 0.0 $z] 0.5]]
    geode addDrawable [osg::ShapeDrawable dr4 [osg::Sphere sph4 [osg::Vec3 c4 6.0 0.0 $z] 0.5]]
    geode addDrawable [osg::ShapeDrawable dr5 [osg::Sphere sph5 [osg::Vec3 c5 8.0 0.0 $z] 0.5]]

    return geode
}

proc CreateScene {} {
    osg::Group group

    # osg:Light allows us to set default parameter values to be used by osg::LightSource
    osg::Light light
    light setLightNum 4
    light setAmbient  [osg::Vec4 amb 0.0 0.0 0.0 0.0]
    light setDiffuse  [osg::Vec4 dif 1.0 0.0 0.0 1.0]
    light setPosition [osg::Vec4 pos 1 0 0 0]
    # last param  w = 0.0 directional light (direction)
    #             w = 1.0 point light (position)

    # light source
    osg::LightSource lightSource
    lightSource setLight light
    group addChild lightSource

    group addChild [CreateSpheres 0]
    group addChild [CreateSpheres 2]
    group addChild [CreateSpheres 4]
    group addChild [CreateSpheres 6]

    [group getOrCreateStateSet] setMode $::GL_LIGHT4 $::osg::StateAttribute_ON

    return group
}

if { ! [tcl3dHaveOsg] } {
    tk_messageBox -icon warning -type ok -title "Missing Tcl3D module" \
                  -message "Sorry, no OpenSceneGraph library available."
    ExitProg
}

# We have the geometry ready. Now create the viewer and the Tk widgets.
osgViewer::ViewerRef viewer [osgViewer::Viewer]

# set the scene-graph data the viewer will render
viewer setSceneData [CreateScene]

viewer setCameraManipulator [osgGA::TrackballManipulator]

if { $argc >= 1 && [lindex $argv 0] eq "-viewer" } {
    # Only use the standard OSG viewer window without any Tk widgets.
    viewer setUpViewInWindow 50 50 500 400
    viewer run
    exit 0
}

# Use the OSG viewer inside a Togl widget.
set osgwin [viewer setUpViewerAsEmbeddedInWindow 50 50 500 400]
tcl3dOsgSetOsgWin $osgwin

viewer realize

CreateWidgets $osgwin

PrintInfo [format "Running on %s %s with a %s (OSG %s, Tcl/Tk %s)" \
           $tcl_platform(os) $tcl_platform(osVersion) \
           [glGetString GL_RENDERER] \
           [tcl3dOsgGetVersion] [info patchlevel]]

if { [file tail [info script]] == [file tail $::argv0] } {
    # If started directly from tclsh or wish, then start animation.
    update
    StartAnimation
}