From 49eb46fefbf4646a2849b960fcea48af79969d89 Mon Sep 17 00:00:00 2001
From: Bryan Housel <bryan@mapbox.com>
Date: Mon, 8 Jan 2018 17:04:30 -0500
Subject: [PATCH] Add epsilon parameter to geoVecEqual

---
 modules/geo/vector.js   | 8 ++++++--
 test/spec/geo/vector.js | 6 +++++-
 2 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/modules/geo/vector.js b/modules/geo/vector.js
index 708bb5f66..e67a6d176 100644
--- a/modules/geo/vector.js
+++ b/modules/geo/vector.js
@@ -1,6 +1,10 @@
 // vector equals
-export function geoVecEqual(a, b) {
-    return (a[0] === b[0]) && (a[1] === b[1]);
+export function geoVecEqual(a, b, epsilon) {
+    if (epsilon) {
+        return (Math.abs(a[0] - b[0]) <= epsilon) && (Math.abs(a[1] - b[1]) <= epsilon);
+    } else {
+        return (a[0] === b[0]) && (a[1] === b[1]);
+    }
 }
 
 // vector addition
diff --git a/test/spec/geo/vector.js b/test/spec/geo/vector.js
index 7b69aab00..20764e80a 100644
--- a/test/spec/geo/vector.js
+++ b/test/spec/geo/vector.js
@@ -1,11 +1,15 @@
 describe('iD.geo - vector', function() {
 
     describe('geoVecEqual', function() {
-        it('tests vectors for equality', function() {
+        it('tests vectors for exact equality', function() {
             expect(iD.geoVecEqual([1, 2], [1, 2])).to.be.true;
             expect(iD.geoVecEqual([1, 2], [1, 0])).to.be.false;
             expect(iD.geoVecEqual([1, 2], [2, 1])).to.be.false;
         });
+        it('tests vectors for equality within epsilon', function() {
+            expect(iD.geoVecEqual([1, 2], [1.0000001, 2.0000001], 1e-5)).to.be.true;
+            expect(iD.geoVecEqual([1, 2], [1.0000001, 2.0000001], 1e-8)).to.be.false;
+        });
     });
 
     describe('geoVecAdd', function() {