Merge pull request #151 from erelsgl/nodejs-examples

Nodejs examples

examples/nodejs/README.md

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+Node.JS examples
+================
+
+To run the examples, you have to install jsts from npm:
+
+    npm install -g jsts

examples/nodejs/binary-operations-1.js

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+/**
+ * Example of calculating intersection between a polygon and a line or a point.
+ */
+
+var jsts = require("jsts");
+var show = require("./show");  // just for showing the geometric objects during the example.
+
+var reader = new jsts.io.WKTReader();
+
+
+var polygon = reader.read('POLYGON((0 0, 0 10, 10 10, 10 0, 0 0))'); // the square between (0,0) and (10,10)
+var line1 = reader.read('LINESTRING(-10 8, 20 8)');
+var line2 = reader.read('LINESTRING(0 11, 11 11)');
+var point1 = reader.read("POINT(7 7)");
+var point2 = reader.read("POINT(11 11)");
+
+show("polygon",polygon);
+show("line1",line1);
+show("line2",line2);
+show("point1",point1);
+show("point2",point2);
+
+show("line1 ^ polygon", line1.intersection(polygon));
+show("polygon ^ line2", polygon.intersection(line2));
+
+show("point1 ^ polygon", point1.intersection(polygon));
+show("polygon ^ point2", polygon.intersection(point2));

examples/nodejs/binary-operations-2.js

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+/**
+ * Example of calculating intersection and union between polygons, normalization and equality checking.
+ */
+
+var jsts = require("jsts");
+var show = require("./show");  // just for showing the geometric objects during the example.
+
+var reader = new jsts.io.WKTReader();
+
+var a = reader.read('POLYGON((0 0, 0 10, 10 10, 10 0, 0 0))'); // the square between (0,0) and (10,10)
+var b = reader.read('POLYGON((5 5, 5 20, 20 20, 20 5, 5 5))'); // the square between (5,5) and (20,20)
+var c = reader.read('POLYGON((15 15, 15 20, 20 20, 20 15, 15 15))'); // the square between (15,15) and (20,20)
+var d = reader.read('POLYGON((5 5, 10 10, 5 15, 0 10, 5 5))'); // a rotated square 
+
+show("a",a);
+show("b",b);
+show("c",c);
+show("d",d);
+
+console.log(a.intersects(b)? "a intersects b": "a does not intersect b");
+var a_intersection_b = a.intersection(b);
+show("a ^ b",a_intersection_b); // the square between (5,5) and (10,10)
+var e = reader.read('POLYGON((5 5, 5 10, 10 10, 10 5, 5 5))'); // also the square between (5,5) and (10,10)
+show("e",e);
+show("a^b equalsExact e",a_intersection_b.equalsExact(e)); // false
+show("a^b equalsTopo  e",a_intersection_b.equalsTopo(e));  // true
+a_intersection_b = a_intersection_b.norm();
+e = e.norm();
+show("a^b normalized",a_intersection_b);
+show("e normalized",e);
+show("a^b normalized equalsExact e normalized",a_intersection_b.equalsExact(e)); // false
+
+console.log(a.intersects(c)? "a intersects c": "a does not intersect c");
+show("a ^ c",a.intersection(c)); // empty intersection
+
+console.log(a.intersects(d)? "a intersects d": "a does not intersect d");
+show("a ^ d",a.intersection(d)); // a RAIT
+
+show("a U b",a.union(b));        // octagon
+show("a U c",a.union(c));        // two disjoint squares
+show("a U d",a.union(d));        // a house-shaped pentagon
+

examples/nodejs/relations.js

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+/**
+ * Calculating the various boolean relations (overlaps, contains, etc.)
+ */
+
+var jsts = require("jsts");
+
+var reader = new jsts.io.WKTReader();
+
+function booleanRelationToString(shape1, shape2, relationName) {
+  var relationHolds = shape1[relationName](shape2);
+  if (relationHolds) {
+    return relationName+"s";
+  } else {
+    return "does not "+relationName;
+  }
+}
+
+var reference = reader.read('POLYGON((0 0, 0 10, 10 10, 10 0, 0 0))'); // the square between (0,0) and (10,10)
+
+var others = {};
+others.internalPoint = reader.read("POINT(7 7)");    // a point inside the square
+others.boundaryPoint = reader.read("POINT(10 5)");    // a point on the boundary of the square
+others.externalPoint = reader.read("POINT(11 11)");  // a point outside the square
+others.farawaySquare = reader.read('POLYGON((20 20, 20 30, 30 30, 30 20, 20 20))'); // the square between (20,20) and (30,30)
+others.cornerSquare = reader.read('POLYGON((10 10, 10 30, 30 30, 30 10, 10 10))'); // the square between (10,10) and (30,30)
+others.sideSquare = reader.read('POLYGON((10 0, 10 30, 30 30, 30 0, 10 0))'); // the rectangle between (10,0) and (30,30)
+others.overlappingSquare = reader.read('POLYGON((5 5, 5 20, 20 20, 20 5, 5 5))'); // the square between (5,5) and (20,20)
+
+var relations = [
+    "disjoint", "touches", 
+    "intersects", //"crosses", 
+    "within", "contains",
+    "overlaps",
+    //"covers", "coveredBy", 
+    "relate"
+    ];
+
+
+for (var p in others) {
+  console.log("\n"+p+"\n-----------------\n");
+  var point = others[p];
+  for (var r in relations) {
+    var relation = relations[r];
+    console.log("reference."+relation+"("+p+") = "+reference[relation](point));
+    console.log(p+"."+relation+"(reference) = "+point[relation](reference));
+  }
+}
+

examples/nodejs/show.js

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+/**
+ * A simple routine for showing geometric objects in the examples.
+ */
+
+
+//var util = require("util");
+module.exports = function (title, polygon) {
+  //console.log(title+" = \n"+util.inspect(polygon,null,3)+" "+(polygon.isEmpty? (polygon.isEmpty() ?" EMPTY": "NONEMPTY"): "")+"\n\n");
+  console.log(title+" = "+polygon.toString()+" "+(polygon.isEmpty? (polygon.isEmpty() ?" EMPTY": "NONEMPTY"): "")+"\n\n");
+};

examples/nodejs/unary-operations.js

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+/**
+ * Example of constructing and translating polygons.
+ */
+var jsts = require("jsts");
+var factory = new jsts.geom.GeometryFactory();
+
+var show = require("./show");  // just for showing the geometric objects during the example.
+
+
+// some shorthands:
+
+function coord(x,y)  {  return new jsts.geom.Coordinate(x,y); }
+function linstr(coords) {  return factory.createLineString(coords); }
+function linring(coords) {  return factory.createLinearRing(coords); }
+function polygon(coords,holes)  { return factory.createPolygon(linring(coords),holes); }
+
+var a = polygon([coord(0, 0), coord(0, 10), coord(10, 10), coord(10, 0), coord(0, 0)]);
+var b = polygon([coord(5, 5), coord(10, 10), coord(5, 15), coord(0, 10), coord(5, 5)]);
+var c = linstr([coord(3,0), coord(3,10)]);
+show("a",a);
+show("b",b);
+show("c",c);
+
+show("a.centroid", a.getCentroid()); //(5,5)
+show("b.centroid", b.getCentroid()); //(5,10)
+show("c.centroid", c.getCentroid()); //(3,5)
+
+show("a.dimension", a.getDimension()); // 2
+show("b.dimension", b.getDimension()); // 2
+show("c.dimension", c.getDimension()); // 1
+
+show("a.type", a.getGeometryType()); // Geometry
+show("b.type", b.getGeometryType()); // Geometry
+show("c.type", c.getGeometryType()); // LineString
+
+show("a.length", a.getLength()); // 40
+show("b.length", b.getLength()); // 20*sqrt(2)
+show("c.length", c.getLength()); // 10
+
+show("a.area", a.getArea()); // 100 (10x10)
+show("b.area", b.getArea()); // 50 (100/2)
+//show("c.area", c.getArea()); // error: a linestring doesn't have area
+
+show("a.envelope", a.getEnvelope()); // == a
+show("b.envelope", b.getEnvelope()); // = the square [0,10]x[5,15]
+show("c.envelope", c.getEnvelope()); // == c
+
+show("a.envelope.area", a.getEnvelope().getArea()); // 100
+show("b.envelope.area", b.getEnvelope().getArea()); // 100