v0.0.39

CHANGELOG.md

@@ -1,3 +1,6 @@
+v0.0.39
+* Added +proj=webmerc
+
 v0.0.38
 * Added geos projection
 

package.json

@@ -1,6 +1,6 @@
 {
 	"name": "mproj",
-	"version": "0.0.38",
+	"version": "0.0.39",
 	"description": "A JavaScript port of the Proj.4 cartographic projections library",
 	"keywords": [
 		"projections",

src/projections/merc.js

@@ -1,7 +1,7 @@
 /* @require pj_phi2, pj_tsfn */
 
-
 pj_add(pj_merc, 'merc', 'Mercator', 'Cyl, Sph&Ell\nlat_ts=');
+pj_add(pj_webmerc, 'webmerc', 'Web Mercator / Pseudo Mercator', 'Cyl, Ell');
 
 function pj_merc(P) {
   var EPS10 = 1e-10;
@@ -55,3 +55,23 @@ function pj_merc(P) {
     lp.lam = xy.x / P.k0;
   }
 }
+
+function pj_webmerc(P) {
+  P.k0 = 1;
+  P.inv = s_inv;
+  P.fwd = s_fwd;
+
+  function s_fwd(lp, xy) {
+    if (fabs(fabs(lp.phi) - M_HALFPI) <= EPS10) {
+      f_error();
+    }
+    xy.x = P.k0 * lp.lam;
+    xy.y = P.k0 * log(tan(M_FORTPI + 0.5 * lp.phi));
+  }
+
+  function s_inv(xy, lp) {
+    lp.phi = M_HALFPI - 2 * atan(exp(-xy.y / P.k0));
+    lp.lam = xy.x / P.k0;
+  }
+}
+

test/projections/webmerc_test.js

@@ -0,0 +1,23 @@
+
+var assert = require('assert'),
+    api = require('../../'),
+    helpers = require('../helpers');
+
+describe('+proj=webmerc', function () {
+  var webmerc = '+proj=webmerc +datum=WGS84';
+  var merc = '+proj=merc +a=6378137 +b=6378137';
+
+  it('test1', function() {
+    helpers.proj_roundtrip(webmerc, [83, 3]);
+  });
+
+  it('test2', function() {
+    var p = [-83, -3];
+    assert.deepEqual(helpers.proj_fwd(webmerc, p), helpers.proj_fwd(merc, p))
+  });
+
+  it('test3', function() {
+    var p = [-9239517, -334111];
+    assert.deepEqual(helpers.proj_inv(webmerc, p), helpers.proj_inv(merc, p))
+  });
+});