Point Classes

The Point and OrientedPoint classes represent points in 3D space, implemented using the three.js library.

• Point is the base class representing a point with a position in 3D space.

• OrientedPoint extends Point and adds orientation information using quaternions. It can also have a camera attached for scene rendering and perspective control.

Points can be retrieved from the scene via the point function (see below). These classes are seldomly interacted with directly except through the latter function. When we do retrieve them, it is mostly to use the getter methods. For example, when we want the basis vector for the reference frame of an OrientedPoint.

Very sparingly one interacts on user scripts with this classes except to retrieve some information from them , such as position or orientation, or to use of the methods on them.

Class: Point

The Point class provides basic functionality for positioning a point in 3D space using a THREE.Group object.

Properties

Property	Type	Description
geometry	THREE.Group	The underlying Three.js object that stores the point's position and transformations.
position	Vector3	Getter: Returns the current position as a tuple [x, y, z].
Setter: Sets the point's position in 3D space.

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Class: OrientedPoint (Subclass of Point)

The OrientedPoint class extends Point and introduces orientation in 3D space using quaternions. It also supports adding a camera to the point.

Constructor

constructor(geometry: THREE.Group, camera?: THREE.PerspectiveCamera)

Parameter	Type	Description
geometry	THREE.Group	A THREE.Group object representing the point in 3D space.
camera	THREE.PerspectiveCamera	(Optional) A camera to be attached to the point.

If a camera is provided, it is added to the point's THREE.Group and named _camera for identification.

Properties

Property	Type	Description
frame	{ x, y, z: Vector3 }	Returns the local coordinate frame vectors (x, y, z) of the point. Each vector is represented as a tuple [x, y, z].
camera	THREE.Camera | null	Getter: Returns the first attached camera named "Camera" in the point's group or null if no such camera exists.

Methods

addCamera

Adds a THREE.PerspectiveCamera with the specified field of view (FOV) to the point's group.

Parameters	Type	Returns	Description
fov: number	number	void	Full FOV of the camera in degrees
camera_orientation	[number, number, number, number]	void	Orientation of the camera with respect to the body frame. Defaults to the identity quaternion with the camera assumed to point in the +z direction.

Throws an error if a camera with the name "Camera" already exists. |

Class: Satellite (Subclass of OrientedPoint)

The Satellite class extends OrientedPoint to represent satellites in orbit. It adds TLE (Two-Line Element) data management and position updating capabilities based on time.

Constructor

constructor(geometry: THREE.Group, noradId: string, state: State, camera_orientation?: [number, number, number, number])

Parameter	Type	Description
geometry	THREE.Group	A THREE.Group object representing the satellite in 3D space
noradId	string	The NORAD ID for the satellite
state	State	The application state object for caching TLE data
camera_orientation	[number, number, number, number]	(Optional) Initial camera orientation quaternion

Methods

updatePosition

Updates the satellite's position based on its TLE data for a given timestamp.

Parameter	Type	Returns	Description
timestamp	Date	Promise<void>	The time for which to calculate the position

Throws an error if TLE data cannot be fetched or parsed, or if position calculation fails.

Properties

Property	Type	Description
noradID	string	Getter: Returns the satellite's NORAD ID

point

Returns a point in the scene state.

Arguments

Parameter	Type	Description
point	string	The name of the point.

Returns

A Point, OrientedPoint, or Satellite instance.

Example

// Calculate the angle between the x-axis of the `sat` point
// and the nadir direction
angle("nadir", point("sat").frame.x);