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Newcomers DBPro Corner / What is A* ?

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Kelebrindae
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Posted: 15th Sep 2003 18:39
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I've read about "A*" algorithms in another post. I guess it's something like recursive floodfill, but it seems more efficient.

Can someone explain me what is "A*" and teach me about its principles ?

Thanx

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Mentor
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Posted: 15th Sep 2003 19:29 Edited at: 15th Sep 2003 19:41
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A* (pronounced A star) is a pathfinding algorythm that allows you find the shortest path between a and b no matter how convoluted or long the path is, if you can get from a to b then A* will find the path, it`s used in games to get the units in rts to get about, and sometimes used in action games to allow the enemies to get to you, you just feed the routine two positions and it finds a path from one to the other, cheers.

http://rajiv.macnn.com/tut/search.html
http://www.policyalmanac.org/games/aStarTutorial.htm

also check the A* code in the codebase


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IanM
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Posted: 15th Sep 2003 22:54
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Don't think that A* is the only search type that may be applicable for your game.

In actual fact, when I wrote that code in codebase I found that it didn't fit well if I had a choice of destinations. That was why I also added the flood search and added distance limits.

So if for example your Bot is low on health and knows the locations of say 4 health packs, you can do a single flood search and find the costs of all those health packs in a single step, rather than doing 4 separate A* searches.
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Kelebrindae
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Posted: 16th Sep 2003 10:10
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Thanks a lot!

The examples in the codebase use DBpro, with custom datatypes. I've got DB classic; do you think I can easily adapt the code for DB classic ? Some suggestions ?

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IanM
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Posted: 16th Sep 2003 10:14
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Ahhh, you might want to quickly nip over the the RGT forums instead then, quickly before the forum closes down.

I believe that there is DBC compatible code over there in their code snippets forum (look for pathfinding and A* in the titles).
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Kelebrindae
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Posted: 16th Sep 2003 10:31
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Err... What are RGT forums ? Where can I find them ?

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IanM
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Posted: 16th Sep 2003 10:34 Edited at: 16th Sep 2003 10:34
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http://www.realgametools.net/forums
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Kelebrindae
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Posted: 16th Sep 2003 10:35
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Thanx again!

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Phaelax
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Posted: 16th Sep 2003 12:20
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On RGT, I think Asheron is the only one that made A* code compatible with DBC. Proteus' uses types, therefore DBP.
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