Extensions Overview

Gladius features an extension system that allows libraries to be created that easily integrate with the engine and provide new functionality that the core library does not provide.

An extension is a collection of three types of items: components, resources, and services.


Components are chunks of functionality and state that can be attached to entities. The cubicvr extension, for example, provides a model component that contains both the data for displaying a 3d model and logic to help render it. In order to render an entity to the screen, you attach a model component to the entity and configure it to the model you want displayed.

Components can also respond to events. If a component has an onX function (where X is replaced with the event type), the function will be called when an event with a matching type is dispatched to the component.

Components can depend on other components in order to function. When a component is added to an entity that does not have other components that it depends on, an error is thrown.


Resources are types of data that generally don’t change and are shared among several entities. This includes things like 3d models, textures, sounds, etc. Extensions don’t define individual resources, but instead define functions that can load resources. The cubicvr extension defines resources for things like light definitions and meshes.

A resource provided by an extension is a function that takes in a piece of data and produces some type of resource. This data is typically retrieved via an XMLHttpRequest, although this behavior can be customized. The returned data is passed to the resource constructor.


Services are lists of tasks that are executed during the game loop. Each task in a service defines which phase of processing it takes part in: input, update, or render. Tasks can also define dependencies between eachother, so that tasks that require other tasks to be complete can be scheduled correctly. For example, the cubicvr extension defines a render task, tied to the render phase, which handles rendering entities in 3d space.

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