Starcraft AI blog

Comments pointed out the new C++ combat simulator FastAPproximation (FAP) by N00byEdge. It’s included in the source of the bot Neohuman, but it has virtually no dependencies and can be easily ported to use in another bot. It is under an MIT license, like UAlbertaBot and Steamhammer, so it also has light legal constraints.

I haven’t tried it yet. No time! Here are my impressions after reading the code.

• I think it’s not quite finished. For one thing, the parent bot that it is part of doesn’t use it yet. For another, it’s still under rapid development. In the last 2 days it has gotten support for stim and medics, and has had at least 2 bug fixes and other changes.

• Even so, bftjoe uses it, so it is in a usable state.

• It’s simple and short and easy to understand. You can read through and easily see its abilities, and its bugs and limitations. SparCraft is large and complex and difficult to understand and modify. I think understandability is a major advantage. If it has problems that affect your bot’s play, you can fix it yourself.

• It supports more stuff than SparCraft. This is a big deal. Unlike SparCraft, FAP explicitly supports bunkers, reavers, and carriers. Overall, SparCraft has major omissions and makes a lot of mistakes with units it does support—for example, the new version claims to handle mutalisks versus spore colonies, but in practice doesn’t do an acceptable job. A combat simulator which handles those things even halfway correctly could have big advantages.

• Its combat simulation is extremely simple. Each unit finds the closest enemy and attacks it as possible, moving toward it until it can. SparCraft has “scripts” that allow much more flexible specification of behavior.

• No support for terrain. SparCraft constrains ground units to walkable terrain. FAP doesn’t read the map at all. Both pretend that units are allowed to freely overlap each other when they move (which in Brood War is only true for air units). Neither understands high ground, which affects visibility and hit probability and makes a giant difference. So SparCraft has a theoretical advantage in simulating ground battles that are in chokes or otherwise affected by terrain obstacles, while both are weak in coping with high versus low ground.

• It ought to be reasonably fast due to its simplicity. With the addition of a location-indexed data structure to find nearest targets quickly, it could be made very fast.

• Other limitations: I didn’t notice any support for suicide units (scourge, infested terrans, spider mines). No splash damage. No support for most spells, not even repair (only stim and medic healing). Details for bunkers, carriers, and reavers are simplified.

• Bugs: The range bonus for a bunker is added on only 1 of 2 #ifdef paths. When a bunker is destroyed, it seems that the 4 fictional marines which are assumed to be in the bunker also disappear, so bunkers will be underestimated.