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# KeyFrame.tcl - Keyframes for vtk
#
# These procs provide a simple (yet powerful) keyframing capability
# for vtk tcl applications
# A keyframe contains a time sorted ordering of methods
# and arguments for an object. Key locations, colors, and
# other parameters are stored and can be interpolated
# at intermediate points.
# The protocol for keyframing is illustrated in the following
# example to keyframe the position of the camera camera1:
# the renderer ren1:
# 1) KeyNew CameraPosition camera1 SetPosition
# create a keyframe for camera1 that will use the
# SetPosition method of the camera
# 2) KeyAdd CameraPosition camera1 [camera1 GetPosition]
# adds the current camera position as a key frame
# 3) Repeat 2, changing the camera position for each step
# 4) KeyRun CameraPosition 30
# runs key frame for 30 steps. Steps that lie
# between keyframes are interpolated with Cubic Splines.
# After each step is interpolated, the proc KeyRender
# is invoked. This proc can be redefined by the use to
# do something more sophisticated. The default proc does
# a: renWin Render
#
############################################
# Create a new keyframe for object and method
proc KeyNew {keyFrame object method} {
upvar $keyFrame a
set a(object) $object
set a(method) $method
set a(counter) 0
set a(debug) 0
}
#
# Reset the keyframe count to 0
proc KeyReset {keyFrame} {
upvar $keyFrame a
set a(counter) 0
if { $a(debug) == 1} {puts "Resetting $keyFrame"}
}
#
# Add a new keyframe with contents value
proc KeyAdd {keyFrame value} {
upvar $keyFrame a
set a($a(counter)) $value
incr a(counter)
}
#
# Run a keyframe for "frames" frames
proc KeyRun {keyFrame frames} {
upvar $keyFrame a
set object $a(object)
set method $a(method)
set depends [llength $a(0)]
#
# create splines if they do not exist
#
for {set j 0} {$j < $depends} {incr j} {
set spline $object${method}Spline$j
if {[info commands $spline] == ""} {
vtkKochanekSpline $spline
}
$spline RemoveAllPoints
}
#
# add points to the splines
#
for {set i 0} {$i < $a(counter)} {incr i} {
for {set j 0} {$j < $depends} {incr j} {
$object${method}Spline$j AddPoint $i [lindex $a($i) $j]
}
}
#
# evaluate splines at key frames
#
for {set i 0} {$i < $frames} {incr i} {
set t [expr ( $a(counter) - 1.0 ) / ( $frames - 1) * $i]
KeyGoto a $t
}
}
# Goto keyframe #
proc KeyGoto {keyFrame t} {
upvar $keyFrame a
set object $a(object)
set method $a(method)
set depends [llength $a(0)]
set keyCommand "$object $method "
for {set j 0} {$j < $depends} {incr j} {
lappend keyCommand "[$object${method}Spline$j Evaluate $t]"
}
if {$a(debug) == 1} {puts "$keyCommand"}
eval $keyCommand
KeyRender
}
# Called after keyframe is executed
proc KeyRender {} {
renWin Render
}
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