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# How to check that two nodes of quadtree are neighbours?

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### #1Turbochist  Members   -  Reputation: 138

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Posted 26 October 2013 - 05:58 AM

Sommet way is working to searching neighbours in the quadtree, but what if two nodes are given allready, and only thing is last it is to check that they both are neighbours to the given direction(N,W,S,E)?

In my algorithm I use Sommet way: I traverse up to the common uncestor and watching nodes for reflection(symmetry). But it is not works properly. As result there are a more than one neighbours matched to the given direction, it's impossible, because one direction - one neighbour.

P.S.

I need this for stitching terrain nodes.

### #2TheUnnamable  Members   -  Reputation: 916

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Posted 26 October 2013 - 09:56 AM

How about simply checking the node's edges? E.g. when checking east, you could do

(node1.x+node1width) == node2.x


And the same for other directions. It would be four checks at most.

### #3Turbochist  Members   -  Reputation: 138

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Posted 26 October 2013 - 02:16 PM

Sorry, i mean Samet neighbor finding techs. Not edges but neighbors. I am trying to check is two nodes are neighbors. Let's depict:

-------------------------

|      |      |      |      |

|-----|-----|-----------|

|      |  a  |  b  |      |

-------------------------

|             |

|      c     |

|             |

-------------

isNeighbor(a, c,  SOUTH) is true

isNeighbor(a, b, EAST) is true

isNeighbor(a, b, WEST) is false

isNeighbor(c, b, NORTH) is false

etc

### #4Turbochist  Members   -  Reputation: 138

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Posted 29 October 2013 - 09:48 AM

TheUnnamable! You are right!

Resolved.

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