...

Generally, there is one shading plugin instance of a RixLightFilter per bound RiLightFilter (RIB) request. This instance may be active in multiple threads simultaneously.

The RIX_LIGHTFILTERPLUGINCREATE macro LIGHTFILTERPLUGINCREATE() macro defines the CreateRixLightFilter() function, which is called by the renderer to create an instance of the light filter plugin. Generally, the implementation of this method should simply return a new allocated copy of your light filter class. Similarly, the RIX_LIGHTFILTERPLUGINDESTROY macro LIGHTFILTERPLUGINDESTROY() macro defines the DestroyRixLightFilter() function called by the renderer to delete an instance of the light filter plugin; a typical implementation of this method is to delete the passed in light filter pointer:

...