nodes2ts

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An extensive port of google's s2 geometry library written in TypeScript.

The only direct dependencies are some math related npm packages (long and math-float64-exponent).

Npm package is nodes2ts.

#### Tests
This project is backed by 60+ 1-by-1 comparison tests between this implementation and the original one.

When implementing a not-yet-ported feature, please generate the needed tests by modifiying the java code within java-test-creator folder

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- S2Loop
- S2Polygon
- S2Polyline


#### Extra code / differences

As already mentioned the lib is almost a 1:1 porting from the java's implementation.

The only exceptions are due javascript limitations such as
- methods and properties can't share the same name
- cant have multiple constructor
- cant overload methods.

The lib also exports a Utils class which contains the following:

``typescript
export declare class Utils {
/**
* Calculates a region covering a circle
* NOTE: The current implementation uses S2Cap while S2Loop would be better (S2Loop is not implemented yet)
* @param center
* @param radiusInKM
* @param points the number of points to calculate. The higher the better precision
* @returns {S2Region}
*/
static calcRegionFromCenterRadius(center: S2LatLng, radiusInKM: number, points?: number): S2Region;
}
`

Also, for some classes, an extra toGEOJSON method is provided to let developer easily inspect boundaries of cells/points.

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- Convert Lat/Lng to S2CellId
`typescript
const cellId = S2CellId.fromPoint(
S2LatLng.fromDegrees(10 /latitude/, 11 /longitude/).toPoint()
);
`

- Get previous or next s2cell
`typescript
// const cellId;
const nextCell = cellId.next();
const prevCell = cellId.prev();
`


- Get All neighbor cell ids of cur level
`typescript
// const cellId;
const neighbors = cellId.getAllNeighbors(cellId.level());
`


- See S2cell on google maps
`typescript
const cell = new S2Cell(cellId);
console.log(cell.toGEOJSON());
// copy the output and paste it on http://geojson.io/
`

Contributing

The library was initially conceived to be used in both server and client env leveraging TypeScript peculiarities.

If you wish to contribute please make sure, wherever applicable, to create a tiny merge request to ease the code
review of the proposed changes.

Want to connect with the author?

If you wish to contact the library author for business (or any other) proposal you can write an email to vekexasia
at gmail dot` com.