[OpenLayers-Users] Can OpenLayers APIs merge line features

[Kevin Yang]

Stephen Woodbridge wrote:
> 
> Kevin Yang wrote:
>> Hello everyone,
>>     A problem troubled me for a long time. Can OpenLayers APIs merge line 
>> features ?I use this function to solve the following problem: When I
>> calculate the shortest path, I get the WKTs of the LineStrings, but it is
>> not arranged  in sequence.So I cannot use the marker' MoveTo method to
>> implement the effct of a  little car picture going along the shortest
>> path
>> in sequence from start-node to end-node. Thus I want to consult you that
>> Can
>> OpenLayers APIs merge line  features ,and how to do it, or is there other
>> ways to solve this problem properly? Thank you very much!
>> best regards,
>> Yang
> 
> I had a similar problem and was using pgRouting. The way I solved it was 
> to have my Ajax server the gets the results from pgRouting do some 
> additional checking and flip the segments so they are all in the same 
> direction along the path. Basically, the segments are returned in the 
> order of first to last, but because you might traverse a segment in the 
> opposite direction than that which it is stored in the database you get 
> the segment in reverse order. Your segments are all stored with A as the 
> start and B as the end. Then you might get results back like:
> 
> 1  2  3  4  5  6
> AB,AB,BA,AB,BA,BA,etc
> 
> So you have to first see if the first segment needs to be flipped:
> 
> if 1A == 2A or 1A == 2B then flip first segment,
> for i=2 through N {
>    if (i-1)B == iB then flip segment i
> }
> 
> now all the segments should be in the correct end to end order. and you 
> can just chain them all together.
> 
> I'm sure you can do the same in Javascript.
> 
> -Steve W.
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> 
> 

Thank you very much ,Steve W.!Best wishes for you! 

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