83 lines
1.8 KiB
Markdown
83 lines
1.8 KiB
Markdown
s2-geometry (JavaScript/ES5.1)
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======================
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A pure JavaScript/ES5.1 port of Google/Niantic's S2 Geometry library (used by **Ingress**, **Pokemon GO**)
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Currently contains basic support for S2Cell
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Simple Examples
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---------------
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```javascript
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var level = 15;
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var latlng = { lat: 40.2574448, lng: -111.7089464 };
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var cell = S2.S2Cell.FromLatLng(latlng, level);
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cell.getNeighbors(); // [ cellLeft, cellDown, cellRight, cellUp ]
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cell.getLatLng(); // { lat: 40.2574448, lng: -111.7089464 }
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var key = cell.toHilbertQuadkey();
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```
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Previous and Next
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-----------------
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You can get the previous and next S2CellId from any given Key:
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1. Convert from Lat/Lng to Key (Face and Hilbert Curve Quadtree)
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2. Get the Previous or Next Key
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3. Convert the Key to an Id (uint64 string)
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```
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var key = S2.latLngToKey(40.2574448, -111.7089464);
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var id = S2.toId(key);
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var nextKey = S2.nextKey(key);
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var nextId = S2.toId(nextKey);
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var prevKey = S2.prevKey(key);
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var prevId = S2.toId(prevKey);
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// See it
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console.log(prevKey);
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console.log(key);
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console.log(nextKey);
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console.log(nextId);
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```
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convert Cell Id to Quadkey
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------------------
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Convert from base 10 (decimal) `S2 Cell Id` to base 4 `quadkey` (aka hilbert curve quadtree id)
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Example '4/032212303102210' becomes '9749618446378729472'
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```
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'use strict';
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var quadkey = '4/032212303102210'
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var parts = quadkey.split('/');
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var face = parts[0]; // 4
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var position = parts[1]; // '032212303102210';
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var level = '032212303102210'.length; // 15
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var cellId = S2.fromFacePosLevel(face, position, level);
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console.log(cellId);
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```
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Convert from hilbert quadtree id to s2 cell id:
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Example '9749618446378729472' becomes '4/032212303102210'
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```
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'use strict';
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var cellId = '9749618446378729472';
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var hilbertQuadkey = S2.toHilbertQuadkey(cellId);
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console.log(hilbertQuadkey);
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```
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