Author Topic: The little bug who grew up to become a feature (Read 10,839 times)

Eóin · « **on:** April 05, 2010, 07:23 PM »

This is a cool little story about a programming arithmetic bug which caused such a cool effect it became a feature. It's a post Bug or feature? from Shawn Hargreave's blog.

KynloStephen66515 · « **Reply #1 on:** April 05, 2010, 10:08 PM »

Wow, such a cool feature caused by such a small accident in the coding stages!

f0dder · « **Reply #2 on:** April 05, 2010, 10:56 PM »

Nice bug

Hadn't see the Shawn Hargreaves name for a long time, brings back memories of DJGPP+Allegro days.

JavaJones · « **Reply #3 on:** April 06, 2010, 02:34 AM »

Hehe, cool story.

- Oshyan

Daleus · « **Reply #4 on:** April 07, 2010, 01:23 PM »

Interesting story.

Without trying to be too philosophical about it, I wonder if there is a lesson to be learned from the story when considering AI.

It would be prudent when working on Artificial Intelligence projects, that we not mistake coding errors for human behaviour.

And that's about as deep as I can go - the thought just popped into my head when reading the blog post.

Please, return to your normally scheduled aspirating.

housetier · « **Reply #5 on:** April 10, 2010, 10:49 PM »

Quite a remarkable story of how subtle differences in rules can lead to completely unexpected behavior

nharding · « **Reply #6 on:** April 11, 2010, 10:41 PM »

Although it wasn't a bug, one of the first games I wrote was Hyperball for the Atari ST. You control a spaceship and fire at a puck to score goals by guiding it into the opponents score line. I had reasonably accurate physics (I think the conservation of angular momentum was just hack rather than correctly implemented from memory), which give the masses of the ships compared the projectiles you fired meant it was better to ram the puck than to fire shots at it. So I made it so that it wouldn't ram the puck (unless the player started to do so, and which case I would up the aggressiveness of the AI). It worked well, but since it would use prediction, so it would work out how far the puck was from the ship, what the movement vectors would be when the shot would get there etc, that it was almost impossible to beat the AI. I just added a difficulty level, on hardest difficulty it would run the AI code every other frame, (it originally ran every frame), and would just run it less often on the easier levels.

All the code was in 68000 assembly language, I miss programming in assembly language now (well I don't miss x86 assembly language that much

)

Neil Harding