Basil Architecture

The overall design of Basil is described in the Basil section of the Architecture document. The general architectural direction is a 3D version of the 2D X Window System. An X11 Server takes connections from multiple clients and presents a model of 2d windows that contain text or graphics. There are different windows managers that connect to the service and presents controls for the user to move and manage the windows.

Basil follows this model for 3D. Multiple object sources connect to Basil and instruct Basil on the coordinates of objects that are defined as meshes, textures, and shaders. Basil handles the job of efficiently displaying the objects in the view.

A user interface manager can connect to Basil and present controls to the user and otherwise manage the appearance and management of the 3D view.

Basil has the concept of a camera and its view frustum which defines the view that is displayed. The camera is moved by external commands and can follow the user’s view of the world. For augmented reality applications, for instance, the camera would be moved to correspond to the user’s head movements. Basil would just display the objects in the current camera’s view.

Objects locations are either relative to the current coordinate space or are relative to the camera/frustum position. By making objects relative to the camera, user interface objects can be created that are always rendered in the same location in the user’s view.

Basil tries to focus only on the tools needed for rendering the 3D scene. These tools should be the minimal and most general functional implementations needed to present general features. For instance, animations added to skeletal models is a way of reducing latency between movement updates and scene display. This makes this a generally usable feature that should be considered for Basil.

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Basil’s internal data model is described in the Basil Item Design document.

Basil’s authentication model and protocol is described in the Basil Authentication document. In general, the authentication/authorization system is opaque to Basil. Basil merely passes around bearer tokens which usually take the form of JWT or OAuth2 tokens.

The common coordinate system is large enough for a planet. The default coordinate system is WGS84 which is earth. For convenience, virtual worlds are mapped to some location on the planet earth.