From 321c65b02312dac62f1fc78a1f25b789dfd3217e Mon Sep 17 00:00:00 2001
From: Tim Schaub <tim.schaub@gmail.com>
Date: Wed, 5 Oct 2016 07:26:41 -0600
Subject: [PATCH] Keep transformed coordinates within valid y range

---
 src/ol/proj/epsg3857.js            |  8 ++++++-
 test/spec/ol/proj/epsg3857.test.js | 35 +++++++++++++++++++++++++++++-
 2 files changed, 41 insertions(+), 2 deletions(-)

diff --git a/src/ol/proj/epsg3857.js b/src/ol/proj/epsg3857.js
index 16dfe11d98..189b770e64 100644
--- a/src/ol/proj/epsg3857.js
+++ b/src/ol/proj/epsg3857.js
@@ -118,8 +118,14 @@ ol.proj.EPSG3857.fromEPSG4326 = function(input, opt_output, opt_dimension) {
       'modulus of output.length with dimension should be 0');
   for (var i = 0; i < length; i += dimension) {
     output[i] = ol.proj.EPSG3857.RADIUS * Math.PI * input[i] / 180;
-    output[i + 1] = ol.proj.EPSG3857.RADIUS *
+    var y = ol.proj.EPSG3857.RADIUS *
         Math.log(Math.tan(Math.PI * (input[i + 1] + 90) / 360));
+    if (y > ol.proj.EPSG3857.HALF_SIZE) {
+      y = ol.proj.EPSG3857.HALF_SIZE;
+    } else if (y < -ol.proj.EPSG3857.HALF_SIZE) {
+      y = -ol.proj.EPSG3857.HALF_SIZE;
+    }
+    output[i + 1] = y;
   }
   return output;
 };
diff --git a/test/spec/ol/proj/epsg3857.test.js b/test/spec/ol/proj/epsg3857.test.js
index 9854d96c20..2402b2854e 100644
--- a/test/spec/ol/proj/epsg3857.test.js
+++ b/test/spec/ol/proj/epsg3857.test.js
@@ -2,6 +2,7 @@ goog.provide('ol.test.proj.EPSG3857');
 
 goog.require('ol.proj');
 goog.require('ol.proj.common');
+
 describe('ol.proj.EPSG3857', function() {
 
   afterEach(function() {
@@ -9,6 +10,38 @@ describe('ol.proj.EPSG3857', function() {
     ol.proj.common.add();
   });
 
+  describe('fromEPSG4326()', function() {
+
+    it('transforms from geographic to Web Mercator', function() {
+      var forward = ol.proj.EPSG3857.fromEPSG4326;
+      var edge = ol.proj.EPSG3857.HALF_SIZE;
+
+      var tolerance = 1e-5;
+
+      var cases = [{
+        g: [0, 0],
+        m: [0, 0]
+      }, {
+        g: [-180, -90],
+        m: [-edge, -edge]
+      }, {
+        g: [180, 90],
+        m: [edge, edge]
+      }, {
+        g: [-111.0429, 45.6770],
+        m: [-12361239.084208, 5728738.469095]
+      }];
+
+      for (var i = 0, ii = cases.length; i < ii; ++i) {
+        var point = cases[i].g;
+        var transformed = forward(point);
+        expect(transformed[0]).to.roughlyEqual(cases[i].m[0], tolerance);
+        expect(transformed[1]).to.roughlyEqual(cases[i].m[1], tolerance);
+      }
+    });
+
+  });
+
   describe('getPointResolution', function() {
 
     it('returns the correct point scale at the equator', function() {
@@ -37,7 +70,7 @@ describe('ol.proj.EPSG3857', function() {
       var epsg4326 = ol.proj.get('EPSG:4326');
       var resolution = 19.11;
       var latitude;
-      for (latitude = 0; latitude < 90; ++latitude) {
+      for (latitude = 0; latitude <= 85; ++latitude) {
         var point = ol.proj.transform([0, latitude], epsg4326, epsg3857);
         expect(epsg3857.getPointResolution(resolution, point)).
             to.roughlyEqual(19.11 * Math.cos(Math.PI * latitude / 180), 1e-9);