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POFaster alternatives to Dijkstra's algorithm for GPS system
 

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  1. POFaster alternatives to Dijkstra's algorithm for GPS system
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    <p>I'm a real speed freak if it gets to algorithms, and in the plugins I made for a game.</p> <p>The speed is.. a bit.. not satisfying. Especially while driving around with a car and you do not follow your path, the path has to be recalculated.. and it takes some time, So the in-game GPS is stacking up many "wrong way" signals (and stacking up the signals means more calculations afterward, for each wrong way move) because I want a fast, live-gps system which updates constantly.</p> <p>I changed the old algorithm (some simple dijkstra implementation) to boost::dijkstra's to calculate a path from node A to node B </p> <p>(total node list is around ~15k nodes with ~40k connections, for curious people here is the map: <a href="http://gz.pxf24.pl/downloads/prv2.jpg" rel="nofollow">http://gz.pxf24.pl/downloads/prv2.jpg</a> (12 MB), edges in the red lines are the nodes),</p> <p>but it didn't really increase in speed. (At least not noticeably, maybe 50 ms).</p> <p>The information that is stored in the Node array is:</p> <pre><code>The ID of the Node, The position of the node, All the connections to the node (and which way it is connected to the other nodes, TO, FROM, or BOTH) Distance to the connected nodes. </code></pre> <p>I'm curious if anybody knows some faster alternatives in C/C++? Any suggestions (+ code examples?) are appreciated!</p> <hr> <p>If anyone is interested in the project, here it is (source+binaries):</p> <p><a href="https://gpb.googlecode.com/files/RouteConnector_177.zip" rel="nofollow">https://gpb.googlecode.com/files/RouteConnector_177.zip</a></p> <p>In this video you can see what the gps-system is like:</p> <p><a href="http://www.youtu.be/xsIhArstyU8" rel="nofollow">http://www.youtu.be/xsIhArstyU8</a></p> <p>as you can see the red route is updating slowly (well, for us - gamers - it is slow).</p> <p>( ByTheWay: the gaps between the red lines have been fixed a long time ago :p )</p>
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    1. COHave you tried A*? It's by the most common (certainly the simplest) heuristic-based path-finding algorithm. And in a GPS-like situation the "distance as the crow flies" heuristic usually works quite well.
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    2. CO@biziclop does boost have an A* implementation? I cannot find anything | google = a* boost or a* algorythm boost
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    3. COThe second optimization possibility comes from the fact that in a GPS-recalculate situation your destination is always the same and your source isn't far from the previous iteration, so if you store the shortest route from the previous calculation, you only need to search until you reach a node that is already on that list.
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