From 9015a27eb6178915c57fb416f93ab09aa94c8d13 Mon Sep 17 00:00:00 2001
From: Michael Kuenzli <michael.kuenzli@camptocamp.com>
Date: Wed, 24 Apr 2019 13:57:15 +0200
Subject: [PATCH] Round coordinate to meter precision before requesting profile

---
 src/SwisstopoProfiler.js | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/src/SwisstopoProfiler.js b/src/SwisstopoProfiler.js
index 7ae4314..128e42e 100644
--- a/src/SwisstopoProfiler.js
+++ b/src/SwisstopoProfiler.js
@@ -34,16 +34,22 @@ class SwisstopoProfiler {
    * @return {Promise}
    */
   computeProfile(segment) {
-    // TODO: round to coordinate to meter precision
+    const geom = /** @type{ol.geom.LineString} */ (segment.getGeometry());
 
-    const geom = this.geojsonFormat_.writeGeometry(segment.getGeometry());
+    // Round coordinate to meter precision by rounding to the fifth decimal place which equals about 1.1 meters.
+    // see: https://gis.stackexchange.com/a/8674
+    const lowerPrecisionCoords = /** @type{Array.<ol.Coordinate>} */
+      (geom.getCoordinates().map(coord => coord.map(c => Number.parseFloat(c.toFixed(5)))));
+    geom.setCoordinates(lowerPrecisionCoords);
+
+    const geojson = this.geojsonFormat_.writeGeometry(geom);
 
     const request = fetch(this.url_, {
       method: 'POST',
       headers: {
         'Content-Type': 'application/x-www-form-urlencoded'
       },
-      body: `geom=${geom}&sr=2056&offset=1&elevation_models=COMB`
+      body: `geom=${geojson}&sr=2056&offset=1&elevation_models=COMB`
     });
     return request
       .then(response => response.json())