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Move posts in categories and add post about buffered poyline

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Daniel Kempkens 2014-03-23 22:16:41 +01:00
parent f66e90083c
commit 13609812b6
5 changed files with 53 additions and 1 deletions

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

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

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--- ---
layout: post layout: post
title: Telegram and Security 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] tags: [telegram, whatsapp, app, english]
image: image:
feature: abstract-2.jpg feature: abstract-2.jpg

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---
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)

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