Hello Sebastian,
thank you for your explanation. I wrote this question here as I thought that maybe somebody has tried it before as this feature is included in many games, so I guess Im not the first one using OSG with this idea. Anyway, is it is off-topic, feel free to contact me directly instead of using the user list. About the problem, well I know that there are hundreds of approaches, but as I am not an expert, I was wondering if there was an available library that has smarter solutions than those I can implement by reading the literature. And if the data (polygons and such) could be easily integrated into OSG. So, if you could suggest one library, it would be a good starting point for me. Something simple for the beginning, imagine that I define a simple map (defining coordinates or polygons) and I want to display that map only in the OSG scene. Thank you again. Cheers From: [email protected] [mailto:[email protected]] On Behalf Of Sebastian Messerschmidt Sent: miércoles, 20 de febrero de 2013 10:33 To: OpenSceneGraph Users Subject: Re: [osg-users] GPS-like map Hello Héctor, Hello Sebastian, thank you for your quick reply. Let me re-explain my question. The main point is the navigation system. I am looking for something like the following: - There is a 2D map (we dont care now about how the map has been made). - The system gets the map as an input with a starting point and a destination. - The system has to calculate the shortest route (maybe with A* algorithm or similar) from the starting point to the destination, and avoiding obstacles (that are defined in the map). Lets think in static obstacles only. - The map and the route have to be displayed in the OSG scene (in the HUD, for example, but thats not a problem for me). So, I need to know if there is a way to define the map with obstacles (with coordinates of whatever), load it into any library, calculate the route and transform the coordinates of the map and the route into something that can be displayed into OSG. Thank you. Cheers Okay, I see your question is a bit off-topic. But I'll give you some hints anyways. In my company we developed different algorithms and tools to create such navigation meshes, to calculate (weighted) shortest paths and to navigate a map. Basically one option is to define polygons (which are not necessarily your database polygons, and should be convex) which can be visited by a model. These polygons have neighbor which define edges for moving from polygon A to B. Now simply treat those polygons (e.g. their center of gravity) as nodes in a graph, and all edges between the polygons as edges in the graph (potentially with a weight). The resulting graph can then be traversed with A* or similar algorithms. Also another option is to skip the polygons and simply place points to positions that are reachable, and define edges. So basically you sort of draw your graph to your map. Then you would again use A* on this data structure. As for the display of the resulting route; simply draw the resulting line-segments from you A* search. There are a lot of papers about automatic/semi-automatic navigation and map creation, based on obstacle geometries, visitable polygons etc. You will find literally hundreds of approaches, but I'm sorry that I cannot point to a specific one, as everything is dependent on your scene. hth Sebastian
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