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Getting Started with Plugins

This guide walks you through creating your first MCA Editor plugin — a simple panel that displays a greeting and adds a menu action.

Step 1: Create the Plugin Folder

Create a new folder in your user plugins directory:

~/Documents/mca_preferences/plugins/my_first_plugin/

Step 2: Write the Manifest

Create plugin.json in your plugin folder:

{
    "id": "com.yourname.my-first-plugin",
    "name": "My First Plugin",
    "version": "1.0.0",
    "author": "Your Name",
    "description": "A simple example plugin",
    "entry_point": "__init__.py"
}

The id should be unique — reverse domain notation is recommended.

Step 3: Write the Plugin

Create __init__.py:

"""
My First Plugin — a simple example MCA Editor plugin.
"""

from mca_core.plugins import MCAPlugin


class MyFirstPlugin(MCAPlugin):
    """A simple plugin that adds a panel and a menu action."""

    PLUGIN_ID = "com.yourname.my-first-plugin"
    PLUGIN_NAME = "My First Plugin"
    PLUGIN_VERSION = "1.0.0"
    PLUGIN_AUTHOR = "Your Name"
    PLUGIN_DESCRIPTION = "A simple example plugin"

    def activate(self, api):
        """
        Called when the plugin is loaded.

        :param MCAPluginAPI api: The plugin API instance.
        """
        self._api = api

        # Lazy import Qt so the module can be discovered without Qt.
        from mca_qt.qt_compat import QWidget, QLabel, QVBoxLayout

        # Build the panel widget.
        self._panel = QWidget()
        layout = QVBoxLayout(self._panel)
        layout.addWidget(QLabel("Hello from My First Plugin!"))

        # Register the panel in the right sidebar.
        self._api.add_panel(
            "my-first-panel",
            "My Plugin",
            self._panel
        )

        # Add a menu action under Plugins > My First Plugin > Greet.
        self._api.add_menu_action(
            "My First Plugin",
            "Greet",
            self._greet
        )

    def deactivate(self):
        """Called when the plugin is unloaded. Clean up resources."""
        self._api.remove_panel("my-first-panel")
        self._panel = None
        self._api = None

    def _greet(self):
        """Menu action callback — writes a greeting to the output panel."""
        self._api.write_output("Hello from My First Plugin!", level="info")

Step 4: Load It

  1. Open MCA Editor in Maya
  2. Go to Plugins menu — your plugin should appear
  3. The panel is available in the right sidebar

If you don't see it, check that the folder structure is correct:

~/Documents/mca_preferences/plugins/
    my_first_plugin/
        plugin.json
        __init__.py

Step 5: Iterate

To reload your plugin after making changes:

  1. Disable the plugin from the Plugins menu
  2. Re-enable it

Development workflow

Keep your plugin folder open in Project Mode alongside Maya. Edit, disable/enable, and test — all within MCA Editor.

Debugging Tips

  • Output panel is your friend — Use api.write_output(str(value), level="info") anywhere in your plugin to inspect values without leaving MCA Editor.
  • Check the manifest first — Most load failures are caused by malformed plugin.json. Validate it at jsonlint.com if your plugin doesn't appear.
  • Module-level imports fail silently — If your plugin doesn't appear at all (not just fails to activate), a module-level import is likely crashing. Move all imports inside activate().

What's Next