The author of this code is Nathan Rusch. It is a fast and easy way to bake the expressions you have on your nodes. I use it on itself and also in other codes I have written.
Expand Bake Expressions
'''
Bake Expressions
Author: Nathan Rusch
Updated: January 27, 2013
'''
import nuke
def bakeExpressions(nodes=None, start=None, end=None, views=None):
'''
Bakes all expression-driven Array_Knob-derived knob components to keyframes
over a given input frame range and list of views.
'nodes': Optional iterable of nodes. If omitted, the current node selection
will be used.
'start'/'end': Optional frame values defining the range to bake. If 'start'
is omitted, the script's first frame will be used; likewise, if 'end' is
omitted, the last frame of the script will be used.
'views': Optional list of views to bake. If omitted, all script views will
be used.
'''
if nodes is None:
nodes = nuke.selectedNodes()
if not nodes:
nuke.message('No nodes to bake')
return
scriptRange = nuke.root().frameRange()
if start is None:
start = scriptRange.first()
if end is None:
end = scriptRange.last()
if views is None:
views = nuke.views()
elif not views:
nuke.message('No views to bake')
return
elif not set(views).issubset(nuke.views()):
nuke.message('Not all views in %s exist in script' % views)
return
for node in nodes:
for knob in node.knobs().itervalues():
if isinstance(knob, nuke.Array_Knob):
for view in views:
# There's currently no way to ask a knob if it has an
# expression at a given view, so we have to check the
# AnimationCurve objects for that. However, we can still
# use knob.isAnimated() to partially optimize this.
if knob.isAnimated(view=view):
aSize = 1 if knob.singleValue(view) else knob.arraySize()
for index in range(aSize):
anim = knob.animation(index, view=view)
if anim is None or anim.noExpression():
continue
for f in range(start, end + 1):
#knob.setValueAt(anim.evaluate(f), f, index)
anim.setKey(f, anim.evaluate(f))
knob.setExpression('curve', channel=index, view=view)
# Even if the expression would have evaluated to a
# constant (flat) curve, we can't tell until after
# it has been baked and the expression is gone.
if anim.constant():
knob.clearAnimated(index, view=view)
def promptAndBake():
'''
Simple GUI wrapper for the ``bakeExpressions`` function that prompts for an
input frame range and view list, and always operates on the selected nodes.
'''
nodes = nuke.selectedNodes()
if not nodes:
nuke.message('No nodes selected')
return
fr = nuke.getFramesAndViews("Range to Bake", str(nuke.root().frameRange()))
if fr is None:
return
fr, v = fr
try:
fr = nuke.FrameRange(fr)
except ValueError as e:
nuke.message(str(e))
return
bakeExpressions(nodes=nodes, start=fr.first(), end=fr.last(), views=v)