Move posts in categories and add post about buffered poyline

_posts/2014-02-16-joining-a-list-of-binaries-in-erlang.md

@@ -2,6 +2,7 @@
 layout: post
 title: Joining a List of Binaries in Erlang
 description: "Description and implementation of a function that joins a list of binaries."
+category: posts
 tags: [erlang, programming, english]
 image:
   feature: abstract-3.jpg

_posts/2014-02-17-exchange-reverse-proxy-using-nginx.md

@@ -2,6 +2,7 @@
 layout: post
 title: Exchange Reverse Proxy Using nginx
 description: "Simple nginx configuration that allows you to proxy most of Microsoft Exchange."
+category: posts
 tags: [nginx, exchange, ops, english]
 image:
   feature: abstract-10.jpg

_posts/2014-02-24-telegram-and-security.md

@@ -1,7 +1,8 @@
 ---
 layout: post
 title: Telegram and Security
-description: "Simple nginx configuration that allows you to proxy most of Microsoft Exchange."
+description: "Some links regarding Telegram and its security model."
+category: posts
 tags: [telegram, whatsapp, app, english]
 image:
   feature: abstract-2.jpg

_posts/2014-03-23-buffered-polyline.md

@@ -0,0 +1,49 @@
+---
+layout: post
+title: Buffered Polyline
+description: "Blow up a polyline to search inside the generated polygon."
+category: posts
+tags: [javascript, programming, english]
+image:
+  feature: abstract-7.jpg
+  credit: dargadgetz
+  creditlink: http://www.dargadgetz.com/ios-7-abstract-wallpaper-pack-for-iphone-5-and-ipod-touch-retina/
+comments: true
+share: true
+---
+
+At work, we needed a simple way to buffer a polyline in order to search for stuff along the route from A to B. I'll explain how we used Google's Map API and [JSTS](https://github.com/bjornharrtell/jsts) in order to achieve this easily.
+
+The first thing we had to do, was to "transform" each element in the overview_path (which the `DirectionsService` returns) to GeoJSON, because that's what JSTS understands.
+
+{% highlight javascript linenos %}
+var overviewPath = response.routes[0].overview_path,
+    overviewPathGeo = [];
+for(var i = 0; i < overviewPath.length; i++) {
+    overviewPathGeo.push(
+        [overviewPath[i].lng(), overviewPath[i].lat()]
+    );
+}
+{% endhighlight %}
+
+The next step was getting `overviewPathGeo` into JSTS and letting it do the work of buffering the line.
+
+{% highlight javascript linenos %}
+var distance = 10/111.12, // Roughly 10km
+    geoInput = {
+        type: "LineString",
+        coordinates: overviewPathGeo
+    };
+var geoReader = new jsts.io.GeoJSONReader(),
+    geoWriter = new jsts.io.GeoJSONWriter();
+var geometry = geoReader.read(geoInput).buffer(distance);
+var polygon = geoWriter.write(geometry);
+{% endhighlight %}
+
+The `polygon` variable now contains a polygon that neatly fits around the `overviewPath`, with a *distance* (buffer size) of roughly 10km.
+
+Since it is nested, you need to call `polygon.coordinates[0]` in order to get back the coordinates of the polygon (as GeoJSON).
+
+You could then use the the coordinates to draw the generated polygon on the map (along with the route), in order to produce something like this:
+
+![Image of the resulting polygon]({{ site.url }}/assets/img/buffered-polyline-1.png)