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Custom Properties

April 25th, 2020

License: CC-BY Free
Sybren Stüvel
Sybren Stüvel Publisher

Custom Properties allow you to attach your own data to things in Blender. In this episode of Scripting for Artists Sybren shows how to create an importer that loads all OBJ files in a directory, and then allows reloading OBJ files with the click of a button.

  • Different kind of properties: 00:24
  • Starting a new add-on with empty panel: 01:14
  • Adding a property to the scene: 03:36
  • Setting property subtypes: 06:35
  • Drawing the property in a panel: 08:03
  • Creating mass-importing operator: 08:51
  • Adding a property to all objects: 10:09
  • Importing OBJ files: 11:54
  • Re-importing OBJ files: 15:22
  • Deleting objects from the scene: 17:15
  • Moving code into a function: 19:!2

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3 comments

Samuel Bernou
Samuel Bernou
April 26th, 2020

Super cool ! Thank you for the list copy trick when iterating while altering the content !

Question about custom properties. Can they store a specific blender object type (or a pointer to a specific blender object !?).
Exemple for my use case on an active grease pencil object:

>>> bpy.context.object.data.layers['Lines'].frames[0].strokes[1]
bpy.data.grease_pencils['Suzanne']...GPencilStroke

I want to store direct access to this stroke, because data_path has good chance to become invalid (layer name can change, as for both frame and stroke index).
If I assign this in a variable it works well for the curent session, but once I save and reload/revert the file I lost the references... Is there a way to store this type using properties ?

Sybren Stüvel
Sybren Stüvel
April 28th, 2020

*@Samuel Bernou* You could have a look at bpy.props.PointerProperty, that might do what you need.

Samuel Bernou
Samuel Bernou
May 2nd, 2020

*@Sybren A. Stüvel* Ok, I tried with a pointer prop, but I obviously don't understand how it work (or maybe it's not possible with GP strokes)

>>> strokeid_3 = C.object.data.layers.active.active_frame.strokes[3].rna_type
>>> bpy.types.Scene.three = bpy.props.PointerProperty(type = strokeid_3, name = "three")
TypeError: PointerProperty(...) expected an RNA type, failed with type 'GPencilStroke'
Traceback (most recent call last):
  File "<blender_console>", line 1, in <module>
ValueError: bpy_struct "Scene" registration error: three could not register

But yeah PointerProperty would have been the way to go. Thank you for pointing this ;)

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