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Code Snippets / YAA*AI (Yet Another A* Algorithm Implementation)

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Owl
20
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Joined: 28th Sep 2003
Location: Imatra, Finland
Posted: 2nd Oct 2003 16:35
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Okay, I just have to get attention: I know there's been some threads about this, and also that there is (at least should be) snippets in the codebase regarding A* and other pathfinding algorithms, but I just had to figure this on my own. For some odd reason. And now that I've done it, I need some publicity, otherwise it would've been coded for nothing.

...and I thought I'd also ask at the same that if people could go over this and give feedback (how to improve, bugs, etc...).

I know about some already, but it's in enough working condition to say that it works. 8-D

I believe that most of the overhead in that is basically the "live observation"...

Here are some media files for it (1bpp bitmaps representing maps)
http://corrie.scp.fi/users/jani.karkkainen/m100x100.bmp
http://corrie.scp.fi/users/jani.karkkainen/m8x8.bmp
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Owl
20
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Joined: 28th Sep 2003
Location: Imatra, Finland
Posted: 2nd Oct 2003 19:09
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Agh. HUGE Bug(tm). A little bit of thinking and some more reading on the subject, I believe it is now bugless (hah! ). Here's the new code.
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Owl
20
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Joined: 28th Sep 2003
Location: Imatra, Finland
Posted: 2nd Oct 2003 19:27
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Umm. Damn.

Third time is the ticket. This time I won't put the whole code, it seems too wasteful.. so, on line 125:

if (estimate < curnode.cost + curnode.heuristic)

change that to

if (estimate < a_list(closed, inclosed).cost + a_list(closed, inclosed).heuristic)

and NOW it should work correctly. If it doens't, I'll curl up and die.
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IanM
Retired Moderator
21
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Joined: 11th Sep 2002
Location: In my moon base
Posted: 2nd Oct 2003 21:44
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It works ... if you change the mapwidth/mapheight variables to match your bitmap size

Nice one!
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ReD_eYe
21
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Joined: 9th Mar 2003
Location: United Kingdom
Posted: 2nd Oct 2003 21:59 Edited at: 2nd Oct 2003 22:02
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hehe, i had to wait abit but it works good!


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Owl
20
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Joined: 28th Sep 2003
Location: Imatra, Finland
Posted: 3rd Oct 2003 18:20
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Oh yes, I noticed that too... I'll be fiddling with it a bit for a while, and probably tidy the code and stuff, before I incorporate it into my game... I think it would be way faster if I discarded the drawing of the map and progress and so on. I'm not gonna test that yet though, because it's fun to watch that thing go!

Thanks for the input, gives me more motivation to continue to code!
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