Created
March 19, 2015 11:27
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Blender property and callbacks
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""" | |
Example of callbacks used for Blender integer property | |
""" | |
import bpy | |
# Some global values | |
values = {} | |
default_value = -1 | |
# Callback function called, when property is changed | |
def cb_update(self, context): | |
print('cb_update() my_prop, value: ', self.name, self.my_prop, values) | |
return None | |
# Callback function called, when value is requested using obj.my_prop. | |
# Note: value of property is generated from other source (dictonary in this | |
# case). | |
def cb_get(self): | |
# Do not call self.my_prop inside this callback function, because it will | |
# cause infinity recursive calling of this function! | |
print('cb_get() my_prop, value: ', self.name) | |
try: | |
value = values[self.name] | |
except KeyError: | |
value = default_value | |
return value | |
# Callback function called, when new value of property is set using: | |
# obj.my_prop = 17. Note: Use this function, when you want to | |
# control the value of property and save it somewhere else (dictionary | |
# in this case). | |
def cb_set(self, value): | |
print('cb_set() my_prop, value: ', self.name, self.my_prop, value) | |
# Do not do this: self.my_prop = value, because it will cause | |
# recursive calling of this callback function | |
values[self.name] = value | |
return None | |
# Create new property in object | |
bpy.types.Object.my_prop = bpy.props.IntProperty(name="MyProp", | |
default=-1, | |
description="My Property", | |
update=cb_update, | |
get=cb_get, | |
set=cb_set | |
) | |
# Simple tests of callback functions | |
print(bpy.context.active_object.my_prop) | |
bpy.context.active_object.my_prop = 10 | |
print(bpy.context.active_object.my_prop) |
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This solution is not perfect. There will be serious problem, when e.g.: blend file will be reloaded. There are some useful notes at Blender stack exchange: http://blender.stackexchange.com/questions/27361/duplicating-object-and-default-value-of-property