插件#

插件 可以让您使用 Python 扩展 Blender 的功能。大多数情况下，您可以从扩展系统中获取插件。

Tip

如果启用后插件功能未激活，请打开控制台窗口，检查是否有错误发生。

互联网访问#

如果插件需要使用互联网，则必须检查（只读）属性 bpy.app.online_access。该选项由偏好设置控制，可以通过命令行（--offline-mode / --online-mode）进行覆写。

为了更好地获取错误信息，还可以检查 bpy.app.online_access_overriden，以确定用户是否可以将允许联机访问打开。

Note

遵循此设置的插件只有在启用的情况下才会连接到互联网。然而，Blender 无法阻止第三方插件违反这一规则。

打包依赖#

For add-ons to be bundled as extensions, they must be self-contained. That means they must come with all its dependencies. In particular 3rd party Python modules.

There are a few options for this:

Bundle with Python Wheels.

This is the recommended way to bundle dependencies.

Bundle other add-ons together.

This is recommended if an add-on depends on another add-on.

Make sure that both the individual and the combined add-on check for already registered types (Operators, Panels, ...). This avoids duplication of operators and panels on the interface if the add-ons are installed as a bundle and individually.

与 Vendorize 捆绑

This can be used as a way to bundle a pure Python dependencies as a sub-module.

This has the advantage of avoiding version conflicts although it requires some work to setup each package.

Local Storage#

Add-ons must not assume their own directory is user writable since this may not be the case for "System" repositories. Writing files into the add-on's directory also has the down side that upgrading the extension will remove all files.

Add-ons which need their own user directory should use a utility function provided for this purpose:

extension_directory = bpy.utils.extension_path_user(__package__, path="", create=True)

If you wish create subdirectories, this can be done with the path argument.

This directory will be kept between upgrades but will be removed if the extension is uninstalled.

旧式 vs 扩展插件#

With the introduction of Extensions in Blender 4.2, the old way of creating add-ons is considered deprecated. While the changes are rather small they impact existing add-ons.

In order to allow a smooth transition process, the so-called legacy add-ons will continue to be supported by Blender. They can be installed via Install legacy Add-on button in the User Preferences.

All add-on maintainers are urged to convert the add-ons they want to share, so they are future proof and can support features like updating from the extensions platform.

将一个旧式插件转换为扩展#

  1. Create a manifest file.

  2. Remove the bl_info information (this is now in the manifest).

  3. Replace all references to the module name to __package__.

  4. Make all module imports to use relative import.

  5. Use wheels to pack your external Python dependencies.

  6. 记住要进行彻底的测试。

Note

For testing it is import to install the extension from disk and check if everything is working well. This will get you as close to the final experience as possible.

扩展与命名空间#

The legacy add-ons would use their module name to access the preferences. This could lead to a name clash when extensions with the same name (from different repositories) would be installed. To prevent this conflict, the repository name is now part of the namespace.

For example, now instead of kitsu the module name would be bl_ext.{repository_module_name}.kitsu instead.

This has a few implications for preferences and module imports.

用户设置与 __package__#

Add-ons can define their own preferences which use the package name as an identifier. This can be accessed using __package__.

This was already supported in the legacy add-ons, but not reinforced. As such this can break backward compatibility.

以前：

class KitsuPreferences(bpy.types.AddonPreferences):
    bl_idname = "kitsu"
    # ... snip ...

# Access with:
addon_prefs = bpy.context.preferences.addons["kitsu"]

现在：

class KitsuPreferences(bpy.types.AddonPreferences):
    bl_idname = __package__
    # ... snip ...

# Access with:
addon_prefs = bpy.context.preferences.addons[__package__]
Sub-packages

An add-on that defines sub-packages (sub-directories with their own __init__.py file) that needs to use this identifier will have to import the top-level package using a relative import.

from .. import __package__ as base_package

Then base_package can be used instead of __package__. The .. imports relative to the packages parent, sub-sub-packages must use ... and so on.

Note

  • The value of __package__ will vary between systems so it should never be replaced with a literal string.

  • Extensions must not manipulate the value of __package__ as this may cause unexpected behavior or errors.

相对导入#

以前:

from kitsu import utils

现在:

from . import utils

Importing packages within the add-on module need to use relative paths. This is a standard Python feature and only applicable for add-ons that have multiple folders.

This was already supported in the legacy add-ons, but not reinforced. As such this can break backward compatibility.