Loading Plugins at Startup

This guide discusses how to configure plugins to load at startup using C/C++.


You would like your plugin to load at Rhino’s startup.


Rhino will load plugins in two ways:

  1. When Needed (Default). Plugin will not be loaded when Rhino starts. Plugin will be loaded when a plugin defined command is run, when a user selects a plugin defined file import/export type, or if a 3DM file has user data that was created by your plugin.
  2. At Startup. Plugin is loaded when Rhino is loaded and initialized.

To set your plugin to load on startup, you need to override your plugin object’s PlugInLoadTime virtual function and return the load_plugin_at_startup enumerated value.


CRhinoPlugIn::plugin_load_time PlugInLoadTime()
  return CRhinoPlugIn::load_plugin_at_startup;


If you have already loaded your plugin using Rhino’s plugin manager, when debugging for example, then you will need to either remove your plugin’s registry key, which can be found here:



if you are running on a system with limited rights, with user-account control enabled for example, then there will be a corresponding key in HKEY_CURRENT_USER

Or, you can just modify your plugin’s “LoadMode” registry key value. The available values for this key are as follows:

Load mode     Registry Value     Description
load_plugin_when_needed     2 - REG_DWORD, Decimal     Default. Load the first time a plugin command used
load_plugin_at_startup     1 - REG_DWORD, Decimal     Load when Rhino is loaded

The reason this step is required is that the “LoadMode” Registry key value is only written the first time the plugin is loaded (when it is initially installed or registered). This will not be an issue for customers of your plugin for the correct registry key value will be written the first time they load your plugin.