28:null 29:["$","title",null,{"children":"Hello, GEOS-WASM | Christoph Pahmeyer | Observable"}] 2e:Ta6c,viewof mapboxMap = { const container = html`

`; yield container; const map = new mapboxgl.Map({ container, style: "https://demotiles.maplibre.org/style.json", center: [114.18908304876464, 22.26524782726996], zoom: 14 }); map.fitBounds( [ 114.18466329574586, 22.260046420421386, 114.19357895851137, 22.271802170346884 ], { padding: 50, duration: 0 } ); const fcLayerPolygons = { id: "fc-layer-polygons", type: "fill", source: { type: "geojson", data: fc }, paint: { "fill-color": "rgba(0, 0, 255, 0.2)", "fill-outline-color": "blue" }, filter: ["==", "$type", "Polygon"] }; const fcLayerLines = { id: "fc-layer-lines", type: "line", source: { type: "geojson", data: fc }, paint: { "line-color": "rgba(0, 0, 255, 0.2)", "line-width": 5 }, filter: ["==", "$type", "LineString"] }; const fcLayerPoints = { id: "fc-layer-points", type: "circle", source: { type: "geojson", data: fc }, paint: { "circle-color": "rgba(0, 0, 255, 0.2)", "circle-radius": 5 }, filter: ["==", "$type", "Point"] }; map.on("load", function () { map.addLayer(fcLayerPolygons); map.addLayer(fcLayerLines); map.addLayer(fcLayerPoints); function updateBuffer() { const radius = parseFloat(viewof settings.value.radius); const endCapStyle = parseInt(viewof settings.value.endCapStyle); const joinStyle = parseInt(viewof settings.value.joinStyle); const mitreLimit = parseFloat(viewof settings.value.mitreLimit); const singleSided = viewof settings.value.singleSided.length ? true : false; const bufferedFC = buffer(fc, radius, { endCapStyle: endCapStyle, joinStyle: joinStyle, mitreLimit: mitreLimit, singleSided: singleSided }); console.log("bufferedFC", bufferedFC); const bufferedFCLayer = { id: "buffered-fc", type: "fill", source: { type: "geojson", data: bufferedFC }, paint: { "fill-color": "rgba(0, 255, 255, 0.2)", "fill-outline-color": "lightblue" } }; if (map.getSource("buffered-fc")) { map.getSource("buffered-fc").setData(bufferedFC); } else { if (map.getLayer("buffered-fc")) { map.removeLayer("buffered-fc"); } map.addLayer(bufferedFCLayer); } } viewof settings.addEventListener("change", updateBuffer); updateBuffer(); }); }2f:T8f3,fc = ({ type: "FeatureCollection", features: [ { type: "Feature", properties: {}, geometry: { type: "Polygon", coordinates: [ [ [114.18466329574586, 22.267890315905507], [114.18499588966371, 22.266271927897595], [114.1876244544983, 22.2654379046834], [114.18651938438417, 22.267284663689324], [114.18656766414641, 22.267314449925173], [114.18652206659317, 22.267331825226496], [114.18655961751938, 22.26734175396915], [114.18659448623657, 22.267364093637525], [114.18840765953065, 22.26926047026178], [114.18466329574586, 22.267890315905507] ] ] } }, { type: "Feature", properties: {}, geometry: { type: "LineString", coordinates: [ [114.18836474418642, 22.270749753256833], [114.19047832489015, 22.26977675682864] ] } }, { type: "Feature", properties: {}, geometry: { type: "LineString", coordinates: [ [114.18925523757935, 22.267592454487456], [114.19204473495483, 22.26928032747266], [114.19121861457826, 22.26488188644578], [114.19357895851137, 22.266927228364477], [114.1893517971039, 22.26653007693269] ] } }, { type: "Feature", properties: {}, geometry: { type: "Point", coordinates: [114.18949127197267, 22.271802170346884] } }, { type: "Feature", properties: {}, geometry: { type: "Polygon", coordinates: [ [ [114.18646574020386, 22.26391877819981], [114.18558597564699, 22.260503165629643], [114.19245243072511, 22.260046420421386], [114.19225931167604, 22.263759914347176], [114.18646574020386, 22.26391877819981] ], [ [114.18732404708864, 22.26324360558074], [114.19101476669312, 22.26268757862524], [114.19092893600465, 22.260959909347545], [114.187388420105, 22.261218068181], [114.18732404708864, 22.26324360558074] ] ] } } ] })30:T2fd5,buffer = { /* This is a high-level buffer implementation based on GEOS-WASM. Most of the code in this file is copied from Turf.js, with some modifications to make it work with GEOS instead of JSTS. The MIT License (MIT) Copyright (c) 2017 TurfJS Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */ const center = (await import("https://cdn.skypack.dev/@turf/center")).default; const { geomEach, featureEach } = await import( "https://cdn.skypack.dev/@turf/meta" ); const { geoAzimuthalEquidistant } = await import( "https://cdn.skypack.dev/d3-geo" ); const { feature, featureCollection, radiansToLength, lengthToRadians, earthRadius } = await import("https://cdn.skypack.dev/@turf/helpers"); const { Buffer } = (await import("https://cdn.skypack.dev/buffer")).default; const { Geometry } = await import(await FileAttachment("wkx.js").url()); let GEOSFunctions = geos; function GEOSGeomFromWKB(wkb) { const wkbPtr = GEOSFunctions.Module._malloc(wkb.length); GEOSFunctions.Module.HEAPU8.set(wkb, wkbPtr); const geomPtr = GEOSFunctions.GEOSGeomFromWKB_buf(wkbPtr, wkb.length); GEOSFunctions.GEOSFree(wkbPtr); // GEOSFunctions.Module._free(wkbPtr); return geomPtr; } function GEOSGeomToWKB(geomPtr) { // create a pointer that stores the GEOSGeomToWKB_buf length const wkbPtrLength = GEOSFunctions.Module._malloc(4); // set it to 0 GEOSFunctions.Module.setValue(wkbPtrLength, 0, "i32"); // get the wkbPtr and store its length in wkbPtrLength const wkbPtr = GEOSFunctions.GEOSGeomToWKB_buf(geomPtr, wkbPtrLength); // get the actual length from wkbPtrLength const size = GEOSFunctions.Module.getValue(wkbPtrLength, "i32"); // create a Uint8Array from the wkbPtr and the size const wkbView = new Uint8Array( GEOSFunctions.Module.HEAPU8.buffer, wkbPtr, size ); const wkb = new Uint8Array(wkbView); // free the memory GEOSFunctions.GEOSFree(wkbPtr); GEOSFunctions.GEOSFree(wkbPtrLength); const buffer = Buffer.from(wkb); return buffer; } /** * Calculates a buffer for input features for a given radius. Units supported are miles, kilometers, and degrees. * * When using a negative radius, the resulting geometry may be invalid if * it's too small compared to the radius magnitude. If the input is a * FeatureCollection, only valid members will be returned in the output * FeatureCollection - i.e., the output collection may have fewer members than * the input, or even be empty. * * @name buffer * @param {FeatureCollection|Geometry|Feature} geojson input to be buffered * @param {number} radius distance to draw the buffer (negative values are allowed) * @param {Object} [options={}] Optional parameters * @param {string} [options.units="kilometers"] any of the options supported by turf units * @param {number} [options.steps=8] number of steps * @param {number} [options.endCapStyle=1] end cap style (1 = round, 2 = flat, 3 = square) * @param {number} [options.joinStyle=1] join style (1 = round, 2 = mitre, 3 = bevel) * @param {number} [options.mitreLimit=5] mitre limit * @param {boolean} [options.singleSided=false] whether to generate a single-sided or double-sided buffer * @returns {FeatureCollection|Feature|undefined} buffered features * @example * const point = turf.point([-90.548630, 14.616599]); * const buffered = turf.buffer(point, 500, {units: 'miles'}); * */ function buffer(geojson, radius, options) { // Optional params options = options || {}; if (!GEOSFunctions) { GEOSFunctions = options.GEOS; } // use user supplied options or default values const units = options.units || "kilometers"; const steps = options.steps || 8; const endCapStyle = options.endCapStyle || 1; const joinStyle = options.joinStyle || 1; const mitreLimit = options.mitreLimit || 5; const singleSided = options.singleSided || false; // validation if (!geojson) throw new Error("geojson is required"); if (typeof options !== "object") throw new Error("options must be an object"); if (typeof steps !== "number") throw new Error("steps must be an number"); // Allow negative buffers ("erosion") or zero-sized buffers ("repair geometry") if (radius === undefined) throw new Error("radius is required"); if (steps <= 0) throw new Error("steps must be greater than 0"); const results = []; switch (geojson.type) { case "GeometryCollection": geomEach(geojson, function (geometry) { const buffered = bufferFeature( geometry, radius, units, steps, endCapStyle, joinStyle, mitreLimit, singleSided ); if (buffered) results.push(buffered); }); return featureCollection(results); case "FeatureCollection": featureEach(geojson, function (feature) { const multiBuffered = bufferFeature( feature, radius, units, steps, endCapStyle, joinStyle, mitreLimit, singleSided ); if (multiBuffered) { featureEach(multiBuffered, function (buffered) { if (buffered) results.push(buffered); }); } }); return featureCollection(results); } return bufferFeature( geojson, radius, units, steps, endCapStyle, joinStyle, mitreLimit, singleSided ); } /** * Buffer single Feature/Geometry * * @private * @param {Feature} geojson input to be buffered * @param {number} radius distance to draw the buffer * @param {string} [units='kilometers'] any of the options supported by turf units * @param {number} [steps=8] number of steps * @param {number} [endCapStyle=1] end cap style (1 = round, 2 = flat, 3 = square) * @param {number} [joinStyle=1] join style (1 = round, 2 = mitre, 3 = bevel) * @param {number} [mitreLimit=5] mitre limit ratio * @param {boolean} [singleSided=false] whether to buffer just one side of the input line * @returns {Feature} buffered feature */ function bufferFeature( geojson, radius, units, steps, endCapStyle, joinStyle, mitreLimit, singleSided ) { const properties = geojson.properties || {}; const geometry = geojson.type === "Feature" ? geojson.geometry : geojson; // Geometry Types faster than jsts if (geometry.type === "GeometryCollection") { const results = []; geomEach(geojson, function (geometry) { const buffered = bufferFeature( geometry, radius, units, steps, endCapStyle, joinStyle, mitreLimit, singleSided ); if (buffered) results.push(buffered); }); return featureCollection(results); } // Project GeoJSON to Azimuthal Equidistant projection (convert to Meters) const projection = defineProjection(geometry); const projected = { type: geometry.type, coordinates: projectCoords(geometry.coordinates, projection) }; // GEOS buffer operation const isBufferWithParams = endCapStyle || joinStyle || mitreLimit || singleSided; let bufferParamsPtr; if (isBufferWithParams) { bufferParamsPtr = GEOSFunctions.GEOSBufferParams_create(); if (endCapStyle) { GEOSFunctions.GEOSBufferParams_setEndCapStyle( bufferParamsPtr, endCapStyle ); } if (joinStyle) { GEOSFunctions.GEOSBufferParams_setJoinStyle(bufferParamsPtr, joinStyle); } if (mitreLimit) { GEOSFunctions.GEOSBufferParams_setMitreLimit( bufferParamsPtr, mitreLimit ); } if (steps) { GEOSFunctions.GEOSBufferParams_setQuadrantSegments( bufferParamsPtr, steps ); } if (singleSided) { GEOSFunctions.GEOSBufferParams_setSingleSided( bufferParamsPtr, singleSided ); } } // create a GEOS object from the GeoJSON // geojsonToPointers always returns an array of pointers // const geomPtr = GEOSGeomFromWKT(stringify(projected)); const wkb = Geometry.parseGeoJSON(projected).toWkb(); const geomPtr = GEOSGeomFromWKB(wkb); const distance = radiansToLength(lengthToRadians(radius, units), "meters"); let bufferPtr; if (isBufferWithParams) { bufferPtr = GEOSFunctions.GEOSBufferWithParams( geomPtr, bufferParamsPtr, distance ); } else { bufferPtr = GEOSFunctions.GEOSBuffer(geomPtr, distance, steps); } // destroy the bufferParamsPtr if it exists if (bufferParamsPtr) { GEOSFunctions.GEOSBufferParams_destroy(bufferParamsPtr); } // update the original GeoJSON with the new geometry const bufferedWkb = GEOSGeomToWKB(bufferPtr); const buffered = Geometry.parse(bufferedWkb).toGeoJSON(); // destroy the GEOS objects GEOSFunctions.GEOSGeom_destroy(geomPtr); GEOSFunctions.GEOSGeom_destroy(bufferPtr); // Detect if empty geometries if (coordsIsNaN(buffered.coordinates)) return undefined; // Unproject coordinates (convert to Degrees) const result = { type: buffered.type, coordinates: unprojectCoords(buffered.coordinates, projection) }; return feature(result, properties); } /** * Coordinates isNaN * * @private * @param {Array} coords GeoJSON Coordinates * @returns {boolean} if NaN exists */ function coordsIsNaN(coords) { if (Array.isArray(coords[0])) return coordsIsNaN(coords[0]); return isNaN(coords[0]); } /** * Project coordinates to projection * * @private * @param {Array} coords to project * @param {GeoProjection} proj D3 Geo Projection * @returns {Array} projected coordinates */ function projectCoords(coords, proj) { if (typeof coords[0] !== "object") return proj(coords); return coords.map(function (coord) { return projectCoords(coord, proj); }); } /** * Un-Project coordinates to projection * * @private * @param {Array} coords to un-project * @param {GeoProjection} proj D3 Geo Projection * @returns {Array} un-projected coordinates */ function unprojectCoords(coords, proj) { if (typeof coords[0] !== "object") return proj.invert(coords); return coords.map(function (coord) { return unprojectCoords(coord, proj); }); } /** * Define Azimuthal Equidistant projection * * @private * @param {Geometry|Feature} geojson Base projection on center of GeoJSON * @returns {GeoProjection} D3 Geo Azimuthal Equidistant Projection */ function defineProjection(geojson) { const coords = center(geojson).geometry.coordinates; const rotation = [-coords[0], -coords[1]]; return geoAzimuthalEquidistant().rotate(rotation).scale(earthRadius); } return buffer; }31:[{"id":"acf25014314d1ee07ecef23ee06860ace9b23d31613ca7712d64a734c9117d4ebb057c072468702cf48da0bf909d91bae00ea74019c9a639ff9db843fde631fd","href":"https://static.observableusercontent.com/files/acf25014314d1ee07ecef23ee06860ace9b23d31613ca7712d64a734c9117d4ebb057c072468702cf48da0bf909d91bae00ea74019c9a639ff9db843fde631fd","name":"wkx.js","type":"application/javascript","lastModified":1690369998633.328,"size":144106}] 2c:{"id":"6e469cc566aee082","slug":"hello-geos-wasm","title":"Hello, GEOS-WASM","thumbnail":"a83cf4503aef398b4904dee65b361c84cfb5130c04386bcaadfe987f39418922","access_level":"public","create_time":"$D2023-06-29T19:06:36.304Z","update_time":"$D2024-11-25T22:55:25.770Z","view_time":null,"first_public_time":"$D2023-06-29T19:50:50.479Z","has_unpublished_edits":null,"fork":false,"stars":7,"starred":false,"owner":{"type":"team","id":"d2dc6c8d94d1ea2c","login":"chrispahm","name":"Christoph Pahmeyer","avatar_url":"https://avatars-next.observableusercontent.com/5f4a345410b8a1f574bf0beecf9c7b18c1140fb1c085b289e271718ef4ed0d57","tier":"starter_2024"},"version":161,"publish_version":null,"role":null,"authored":false,"authors":[{"type":"individual","id":"e3c99024cde17af0","login":"chrispahm","name":"Christoph Pahmeyer","avatar_url":"https://avatars-next.observableusercontent.com/5f4a345410b8a1f574bf0beecf9c7b18c1140fb1c085b289e271718ef4ed0d57","tier":null}],"members":[{"type":"individual","id":"e3c99024cde17af0","login":"chrispahm","name":"Christoph Pahmeyer","avatar_url":"https://avatars-next.observableusercontent.com/5f4a345410b8a1f574bf0beecf9c7b18c1140fb1c085b289e271718ef4ed0d57","tier":null,"role":"editor"}],"comments":[],"custom_thumbnail":false,"trashed":false,"lapsed":null,"subscribed":null,"forks":2,"collection":{"id":"6c7ff609de80b6e2","slug":"maps","title":"Geo","owner":{"id":"d2dc6c8d94d1ea2c","login":"chrispahm","name":"Christoph Pahmeyer"}},"type":"notebook","body":{"title":"Hello, GEOS-WASM","cells":[{"id":0,"value":"# Hello, GEOS-WASM","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","output":"","database":"$undefined"},{"id":45,"value":"[GEOS](https://github.com/libgeos/geos) is a C++ port of the [Java Topology Suite](\n https://github.com/locationtech/jts\n), a library for performing operations on planar geometry.\nGEOS provides many of the algorithms used by [PostGIS](http://www.postgis.net/), the [Shapely](http://www.postgis.net/) package for Python, the [sf](https://github.com/r-spatial/sf) package for R, and others.\n\nGEOS-WASM a WebAssembly build of GEOS using [Emscripten](https://emscripten.org/). It can be used in the browser or in Node.js, bun, or deno. This notebook is running GEOS ${geos.GEOSversion()}\n\nIf you're interested, please [check out the Github repository!](https://github.com/chrispahm/geos-wasm) ","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","output":"","database":"$undefined"},{"id":49,"value":"viewof settings = Inputs.form({\n radius: Inputs.range([-0.05, 0.5], { label: \"Radius (km)\", value: 0.05 }),\n endCapStyle: Inputs.select([1, 2, 3], {\n label: \"End cap style\",\n format: (s) => (s === 1 ? \"Round\" : s === 2 ? \"Square\" : \"Flat\")\n }),\n joinStyle: Inputs.select([1, 2, 3], {\n label: \"Join style\",\n format: (s) => (s === 1 ? \"Round\" : s === 2 ? \"Mitre\" : \"Bevel\")\n }),\n mitreLimit: Inputs.range([0, 10], {\n label: \"Mitre limit\",\n value: 5,\n step: 1\n }),\n singleSided: Inputs.checkbox([\" \"], { label: \"Single sided\" })\n})","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":59,"value":"$2e","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":56,"value":"$2f","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":11,"value":"geos = {\n const initGeosJs = (\n await import(\"https://cdn.skypack.dev/geos-wasm@3.0.1?min\")\n ).default;\n const geos = await initGeosJs();\n return geos;\n}","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":92,"value":"$30","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":54,"value":"mapboxgl = {\n const mapboxgl =\n await require(\"https://api.mapbox.com/mapbox-gl-js/v2.15.0/mapbox-gl.js\");\n mapboxgl.accessToken =\n \"pk.eyJ1IjoidG9mZmkiLCJhIjoiY2lvMDBxMzR3MDB1eHZza2x4NGI2YjI5OSJ9.IEaNA05pWbT92nOu-lEOYw\";\n const cssHref = \"https://api.mapbox.com/mapbox-gl-js/v2.15.0/mapbox-gl.css\";\n document.head.appendChild(html``);\n return mapboxgl;\n}","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"}],"files":"$W31","stdlib":"1","titling":"auto"}} 2d:"$2c:body"