> Among Skyrim players, you'll occasionally see this tip: if you see a wild fox, follow it and you'll be led to treasure. Sometime shortly after shipping, we saw this going around online, and an informal investigation started. Who made foxes do this?!
> Skyrim uses something called 'navmesh' for AI navigation. For non-dev folks, this is an invisible 3D sheet of polygons that is laid over the world, telling AI where it can and cannot go.
> In most situations, you're seeing AI decide what do to (run at player, hide in cover, etc), use navmesh to make a path, and navigate along that path. Foxes are no different. But their AI is very simplified: they basically can only run away.
> So foxes flee. Why would they flee towards treasure? This is where it gets interesting. If you're close to an AI, it's in "High Process", or the most fancy, cpu-intensive pathfinding. It uses the full navmesh and will do things like line of sight and distance checks.
> To contrast, there's also "Low Process" - used for stuff like NPCs walking a trade route across the world. These are only updated every several minutes, and position is tracked very loosely.
> There is a sort of "Medium Process" for characters nearby, but who didn't need the complex pathing of combat. Because of the way the fox's AI worked (always be fleeing!) it's basically ONLY using this process.
> This is where understanding of how Skyrim uses navmesh comes in. Swaths of the outdoor world have simple navmesh. You don't need to add lots of detail in a space with basic topography, little clutter, or a low chance of combat. So wilderness = small number of big triangles.
> When you stumble across something like a camp, however, navmesh gets way more detailed. Added visual detail means added navmesh detail, and if we're placing NPCs of any kind, we also tend to add even more detail. So Points of Interest = big number of small triangles.
> You see where this is going? The Fox isn't trying to get 100 meters away - it's trying to get 100 triangles away. You know where it's easy to find 100 triangles? The camps/ruins/etc that we littered the world with, and filled with treasure to reward your exploration.
> So foxes aren't leading you to treasure - but the way they behave is leading them to areas that tend to HAVE treasure, because POIs w/loot have other attributes (lots of small navmesh triangles) that the foxes ARE pursuing.
> It's a nerdy little story, but I love it. Emergent Gameplay is often used to describe designed randomness, but this is a case of actual gameplay that NOBODY designed emerging from the bubbling cauldron of overlapping systems. And I think that's beautiful.