LatLngPoint (Geographic Point)

Represents a geographic point with longitude, latitude, and altitude coordinates.

Constructor

new ge3d.LatLngPoint(lng?: number | string, lat?: number | string, alt?: number | string): LatLngPoint

Parameters

Parameter	Type	Default	Description
lng	number | string	0	Longitude value (-180 to 180)
lat	number | string	0	Latitude value (-90 to 90)
alt	number | string	0	Altitude value in meters

Properties

Property	Type	Description
lng	number	Longitude value (-180 to 180)
lat	number	Latitude value (-90 to 90)
alt	number	Altitude value in meters

Instance Methods

Method	Parameters	Return Value	Description
clone	()	LatLngPoint	Create a copy of this point
format	()	this	Format coordinates to specified decimal places
toArray	(noAlt?: boolean)	number[]	Convert to array [lng, lat, alt] or [lng, lat]
toString	()	string	Convert to string "lng,lat,alt"
toCartesian	(clone?: boolean)	Cesium.Cartesian3	Convert to Cesium Cartesian3 coordinates
toCartographic	()	Cesium.Cartographic	Convert to Cesium Cartographic coordinates
toMercator	()	number[]	Convert to Mercator projection coordinates
equals	(other: LatLngPoint)	boolean	Check if two points are equal
valid	()	boolean	Check if coordinates are valid

Static Methods

Method	Parameters	Return Value	Description
parse	(position: any, time?: any)	LatLngPoint	Parse various input types to LatLngPoint
fromArray	(array: number[])	LatLngPoint	Create from array [lng, lat, alt]
fromString	(string: string)	LatLngPoint	Create from comma-separated string
fromCartesian	(cartesian: Cesium.Cartesian3, time?: any)	LatLngPoint	Create from Cesium Cartesian3
fromCartographic	(cartographic: Cesium.Cartographic)	LatLngPoint	Create from Cesium Cartographic
fromMercator	(mercator: number[])	LatLngPoint	Create from Mercator projection coordinates
toCartesian	(input: any, defaultValue?: any)	Cesium.Cartesian3	Convert input to Cartesian3
toCartographic	(input: any, defaultValue?: any)	Cesium.Cartographic	Convert input to Cartographic
toArray	(input: any, noAlt?: boolean)	number[]	Convert input to array

Usage Examples

Basic Usage

// Create a point with coordinates
const point = new ge3d.LatLngPoint(116.3975, 39.9087, 100);

// Access properties
console.log(point.lng); // 116.3975
console.log(point.lat); // 39.9087
console.log(point.alt); // 100

// Modify coordinates
point.lng = 120.0;
point.lat = 40.0;
point.alt = 200;

Creating from Different Sources

// From array
const point1 = ge3d.LatLngPoint.fromArray([116.3975, 39.9087, 100]);

// From string
const point2 = ge3d.LatLngPoint.fromString("116.3975,39.9087,100");

// From Cesium Cartesian3
const cartesian = Cesium.Cartesian3.fromDegrees(116.3975, 39.9087, 100);
const point3 = ge3d.LatLngPoint.fromCartesian(cartesian);

// From Cesium Cartographic
const cartographic = Cesium.Cartographic.fromDegrees(116.3975, 39.9087, 100);
const point4 = ge3d.LatLngPoint.fromCartographic(cartographic);

// Parse any input type
const point5 = ge3d.LatLngPoint.parse({
  lng: 116.3975,
  lat: 39.9087,
  alt: 100
});

Converting to Different Formats

const point = new ge3d.LatLngPoint(116.3975, 39.9087, 100);

// Convert to array
const array = point.toArray(); // [116.3975, 39.9087, 100]
const array2D = point.toArray(true); // [116.3975, 39.9087]

// Convert to string
const str = point.toString(); // "116.3975,39.9087,100"

// Convert to Cesium coordinates
const cartesian = point.toCartesian();
const cartographic = point.toCartographic();

// Convert to object
const obj = point.toObject(); // { lng: 116.3975, lat: 39.9087, alt: 100 }

Working with Map Events

// Listen to map click events
core.addEventListener(ge3d.EventType.click, (event) => {
  // Convert click position to LatLngPoint
  const point = ge3d.LatLngPoint.fromCartesian(event.cartesian);
  console.log('Clicked at:', point.toString());
  
  // Use the point for other operations
  const cartesian = point.toCartesian();
  core.flyToPoint(cartesian);
});

Validation and Comparison

const point1 = new ge3d.LatLngPoint(116.3975, 39.9087, 100);
const point2 = new ge3d.LatLngPoint(116.3975, 39.9087, 100);

// Check if coordinates are valid
if (point1.valid()) {
  console.log('Valid coordinates');
}

// Compare two points
if (point1.equals(point2)) {
  console.log('Points are equal');
}

// Clone a point
const clonedPoint = point1.clone();

Coordinate Systems

LatLngPoint supports conversion between different coordinate systems:

• Geographic (WGS84): Longitude, latitude, altitude
• Cartesian3: 3D Cartesian coordinates in Cesium
• Cartographic: Cesium's geographic representation
• Mercator: Mercator projection coordinates

Notes

1. All coordinate values are automatically converted to numbers
2. Longitude range: -180 to 180 degrees
3. Latitude range: -90 to 90 degrees
4. Altitude is in meters above sea level
5. The format() method rounds coordinates to 8 decimal places for lat/lng and 6 for altitude
6. Static methods provide flexible input parsing for various data formats
7. Coordinate validation ensures values are within valid ranges
8. Caching is used for Cartesian3 conversion to improve performance