Renderer is the core visualization and logical part of any application. It's attached to the Engine. Basically, renders define two methods load() and update(). The first one is used to initialize assets and prepare the scene (lightning, environment map). The second is used to update the scene according to results of video processing. This's where all the logic happens. Renderers can be extended with plugins. Plugins do simple rendering task, for example add object to that follows the head or render avatar overlay.
This package provides set of ready-made renderers and plugins to simplify development of applications. They can be used as both atomic building blocks or you can use them as starting points, inherit and override / extend class functionality. By extending load and update of a Renderer or Plugin's load and update you can add any custom logic, interactions, animations, post-processing, effects, gesture recognition, etc.