Re: [TuxKart-devel] Ideas for AI

[Steve B. <sjb...@ai...>]

Charles Goodwin wrote:
> On Tue, 2004-06-29 at 22:41 -0500, Steve Baker wrote:
> 
>>The thing I'd like to consider is something like a 'vector field'.
>>
>>A large array (and as I explained earlier - it would be LOTS of memory)
>>where for every (say) 2meter x 2meter square there would be (say) two bytes.
> 
> 
> I really think this is an unecessary approach.

[ I'm playing devils advocate here - I want to discuss this some more
to elicit deeper thinking without necessarily agreeing with everything
I'm saying! ]

Where a vector field really scores is when the polygonal representation of
the track is very complex.   With any kind of waypoint representation, there
is an underlying assumption that you can't get stuck behind a wall or
something.  Preventing that from happening in the absence of other
information is really hard.

With waypoints, if I somehow get knocked off the road and there is a
wall between me and the waypoint, I'm completely stuck.

Similarly, if I'm somehow pushed off course and ended up somewhere where
there is a shorter route to the waypoint-after-next than going to the
next waypoint - then I'm probably going to mindlesslyy turn right around,
drive to the waypoint that was supposed to be next and then take the long
way to the waypoint after that.

The vector field approach gives you a fast, reliable way to get out of
any situation.  For any location on the map, you know simply and unambiguously
how to get back to the racing line via the fastest possible route - even if
you have to quite literally negotiate a maze to do it.

I agree though that it's going to be hard to generate and that it'll
consume quite a bit of RAM - so your way may be more practical (I believed
that waypoints were the right thing to do when I first wrote TuxKart - but
practical experience with trying to kludge around various practical
problems leads me to wonder whether something different would help.

We can attempt to fix the problems with waypoints by restricting the
kinds of tracks we generate - but all of the exciting and interesting
possibilities keep tripping up if you impose too many artificial
design limitations.

---------------------------- Steve Baker -------------------------
HomeEmail: <sjb...@ai...>    WorkEmail: <sj...@li...>
HomePage : http://www.sjbaker.org
Projects : http://plib.sf.net    http://tuxaqfh.sf.net
            http://tuxkart.sf.net http://prettypoly.sf.net
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