Documentation for in-fight AI system

[ghost]

Your question

Hi. I'm interested at improving the in-fights AI and would like to have some guidance at where to look in codebase. Ideally, and IRC channel or something I can reach with a bridge, and some documentation, even WiP.

Combat AI still have the old HoMM2 problems imo, at it still does basic tactical mistakes the child I was could consider stupid back in time.
I have not played this since decades, except for the few games I had those last weeks, so I'm likely missing tactics, but it's still too easy, so I think I should be able to fix various issues. This particular side of AI would merit it's own tag, it would help if I really go in hacking this.

Additional info

When looking at open issues, I see those are related to this problem:

• Combat, AI does not optimize the placement of its troops against creatures that attack on two hexagons #2729
• Combat, AI does not optimize the placement of its troops to reach other opposing troops #2750
• Combat, AI does not always make the best tactical choice in the priority of troops to attack #2751
• Fast units should get the first strike in battles #2954
• Combat, AI behavior, AI Hero casts Haste on the Cyclopes just after they have moved (0.9.3 3373) #3380
• Combat, AI behavior, sometimes it is still possible to keep an opposing troop away from the shooters (0.9.3 3373) #3393
• Combat, AI behavior, AI should take into account the spells cast by the opposing hero during the combat before moving its troops (0.9.3 3370) #3416
• Combat, AI behavior, AI uses far too many spell points in combat when it is not necessary to win (0.9.3 3442) #3497
• Combat, AI behaviour, apprehensive AI covers rangers with strong troops, but looses other weaker troops after attack #3508
• Computer casts Haste on flying creatures #3905
• Combat, AI behavior, AI troop doesn't move (0.9.6 4111) #4124
• Combat, AI behavior, AI casts not necessary spells in combat, here Slow and Haste (0.9.6 4111) #4129
• Combat, AI behavior, AI attacks the troop of Hydras with all his troops in close combat at the same time (0.9.6 4111) #4130
• Combat, AI behavior, when an IA troop cannot reach an opposing troop, it should position so that it can reach the opposing troop no matter where the opposing troop positions the next turn when possible (0.9.6 4111) #4148
• Combat, AI behavior, in instant and automatic combat modes, the AI causes troops to be lost when the combat could be won without loss (0.9.7 4208) #4254
• Combat, AI places shooters next to hero's army while maneuvering #4382
• Combat, AI behavior, AI should try to keep its powerful heroes by making them flee before the end of a combat, especially when they also have artifacts (0.9.9 4551) #4585
• Combat, AI behavior, AI Hydras should not move and attack all adjacent troops by staying in the same hexes (0.9.13) #5144
• Combat, AI behavior, AI should not be distracted by troops who inflict little damage and are therefore not a priority (0.9.13 5123) #5147
• Castle siege, defending AI doesn't consider castle walls while creating a path to attack enemy inside castle walls #5325
• Combat, difference of troops hit by the dragons' retaliation (valid for all attacks on two hexagons) compared to the original game (make the AI to be better in its attacks when it comes to creatures that replicate on several hexagons) #5515
• Ai defending a castle will just sit in there with his flying units taking ranged hits until they die #5523
• Combat, difference of troops hit by the dragons' retaliation (valid for all attacks on two hexagons) compared to the original game (make the AI to be better in its attacks when it comes to creatures that replicate on several hexagons) #5515
• Ai defending a castle will just sit in there with his flying units taking ranged hits until they die #5523
• Combat, AI behavior, Hydras are moving backwards when they could get closer to the Centaurs (0.9.17 5637) #5648

[ihhub]

Hi @bmorel , you can look at ai_normal_battle.cpp file for AI action during battle. You can also join our Discord server for discussions about the development.

[ihhub]

I am moving this issue into discussion section.

[ghost]

Just placing a message here to be noticed if more events happen on this. Looking at source code is not really a good way to learn about architecture and concepts.
Myself, I'm starting to be pretty familiar with FPS bots AI mechanisms (expert systems), but not about the mechanisms that need to be used to drive other entities. On that point, an interesting document that might apply partially to HoMM2 is https://www.researchgate.net/publication/240430519_The_Quake_III_Arena_Bot, since it seems they did implemented some kind of "leader" AI, but it was still giving instructions to autonomous AIs.

When I say I'm starting to be familiar, it's just because I've been hacking existing bots for a FOSS FPS game for around 2 years now, with pretty decent results, not that I have any academic knowledge on the matter.

[ihhub]

Hi @bmorel ,

writing documentation is out of the scope of this project so the core team members will not do this as they have much higher priority tasks. AI in Heroes 2 is way more complex than in FPS games due to the scale of logic in the game itself. The best way to understand how it works is actually to read the source code.