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AI: Difference between revisions
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==Pathfinding and movement== | ==Pathfinding and movement== | ||
[[ | [[Image:Pathfinding grid.jpg|thumb|right|alt=Example of a pathfinding grid.|An example of a pathfinding grid.]] | ||
[[ | [[Image:Ai2 showastar2.png|thumb|right|alt=Example of an A*.|An example of the A* algorithm's work: nodes chosen as a path for AI are highlighted.]] | ||
Oni has two ways to make an AI move in a game world - pathfinding, and what could be called vector-based. | Oni has two ways to make an AI move in a game world - pathfinding, and what could be called vector-based. | ||
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==Vision and hearing== | ==Vision and hearing== | ||
[[ | [[Image:VisionFields.jpg|thumb|right|alt=Visualization of vision fields.|An example of a blue Striker's central and peripheral vision.]] | ||
[[ | [[Image:SoundSpheres.jpg|thumb|right|alt=Visualization of sound spheres.|Three examples of sound spheres.]] | ||
When emulating humans with AI, senses have to be taken into an account: sight, hearing, taste, smell, touch. Unfortunately, Oni emulates only sight and hearing. | When emulating humans with AI, senses have to be taken into an account: sight, hearing, taste, smell, touch. Unfortunately, Oni emulates only sight and hearing. | ||
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==Basic combat behaviors== | ==Basic combat behaviors== | ||
[[ | [[Image:combatRanges.png|thumb|right|alt=Example of combat ranges.|Combat ranges of an AI character.]] | ||
Of course, an action game like Oni is not complete without guns blazing and fists flying through the air. But combat in real life is usually very fickle and everything has to be considered. How can Oni's AI possibly deal with such a complex task? | Of course, an action game like Oni is not complete without guns blazing and fists flying through the air. But combat in real life is usually very fickle and everything has to be considered. How can Oni's AI possibly deal with such a complex task? | ||
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[[ | [[Image:GoForGun.jpg|thumb|right|alt=Picture showing AI moving to a weapon.|AI moving towards a weapon.]] | ||
'''Weapon pickup behavior ([[ONCC]] file)''': When in combat mode, an unarmed AI can be told to move to a loaded weapon and pick it up or to swap a held, empty gun for a loaded gun which is lying on the floor. Overall, AIs can only register pickup-able weapons up to a distance of 60 world units (hardcoded). In the ONCC file, these parameters can be set to alter the gun pickup behavior (XML tags in parentheses): | '''Weapon pickup behavior ([[ONCC]] file)''': When in combat mode, an unarmed AI can be told to move to a loaded weapon and pick it up or to swap a held, empty gun for a loaded gun which is lying on the floor. Overall, AIs can only register pickup-able weapons up to a distance of 60 world units (hardcoded). In the ONCC file, these parameters can be set to alter the gun pickup behavior (XML tags in parentheses): | ||
:*Chance for pickup (GoForGunChance): percent chance of AI deciding to go and pick up a weapon. It seems that the weapon closest to the AI character is always chosen to be picked up. | :*Chance for pickup (GoForGunChance): percent chance of AI deciding to go and pick up a weapon. It seems that the weapon closest to the AI character is always chosen to be picked up. | ||
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:*NotUsed: Some characters have this bit turned on, however it looks like it does nothing. | :*NotUsed: Some characters have this bit turned on, however it looks like it does nothing. | ||
[[ | [[Image:Firingspread.png|thumb|right|alt=Example of a firing spread.|Example of a firing spread.]] | ||
[[ | [[Image:Projectile.png|thumb|right|alt=Example of a particle with an AI projectile-dodge radius.|Example of a projectile with AI dodge radius (blue sphere).]] | ||
'''Gunfire dodging mechanics'''. Gunfire dodging mechanics are quite an interesting part of Oni's AI system -- interesting because the retail version displays little to no such behavior, which is sad because it adds challenge to the gunplay. In order to make an AI perform gunfire dodging, this AI must be in combat mode with an enemy. Without combat mode and some enemy, AI character won't dodge. Additionally, an AI will only perform a dodge when the character senses one of these two things: | '''Gunfire dodging mechanics'''. Gunfire dodging mechanics are quite an interesting part of Oni's AI system -- interesting because the retail version displays little to no such behavior, which is sad because it adds challenge to the gunplay. In order to make an AI perform gunfire dodging, this AI must be in combat mode with an enemy. Without combat mode and some enemy, AI character won't dodge. Additionally, an AI will only perform a dodge when the character senses one of these two things: | ||
:*Firing spread. This can be seen by using [[ai2_showfiringspreads]]. The firing spread has the shape of a prism (its dimensions set in ONWC) which can be created when a weapon is fired. Not every gun has a firing spread, as for some guns a firing spread is useless (e.g. the Scram Cannon and Super Ball Gun). If an AI can dodge gunfire and intersects with a firing spread, this AI character starts its gunfire dodging behavior. | :*Firing spread. This can be seen by using [[ai2_showfiringspreads]]. The firing spread has the shape of a prism (its dimensions set in ONWC) which can be created when a weapon is fired. Not every gun has a firing spread, as for some guns a firing spread is useless (e.g. the Scram Cannon and Super Ball Gun). If an AI can dodge gunfire and intersects with a firing spread, this AI character starts its gunfire dodging behavior. | ||
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==Melee combat behaviors== | ==Melee combat behaviors== | ||
Ah yes. After all those OTHER things, we finally get to how the AI system handles the core gameplay feature of this game, hand-to-hand combat. First things first. As usual, a player can see her/his enemy trying to perform some move and react to it. An AI, however, cannot see a thing because it does not have eyes, nor a human brain. Thus the first question is, How does the AI learn about incoming attacks? | Ah yes. After all those OTHER things, we finally get to how the AI system handles the core gameplay feature of this game, hand-to-hand combat. First things first. As usual, a player can see her/his enemy trying to perform some move and react to it. An AI, however, cannot see a thing because it does not have eyes, nor a human brain. Thus the first question is, How does the AI learn about incoming attacks? | ||
[[ | [[Image:Melee zones.jpg|thumb|right|alt=Melee zones around a character|A rough illustration of melee zones.]] | ||
:The answer lies within the [[TRAM]] files. Each animation which can hurt somebody should have "extents". Extents are invisible boundaries which tell the AI about the range of enemy attacks. There are two types, horizontal and vertical, but the more important thing AI-wise is that, without extents, attack TRAMs will not be registered by AI characters as attacks, so AI will not try to block or dodge them. As long as the attack has extents data, then the AI will have the needed knowledge of the path of the attacking character's body parts (see attack part of [[TRAM]]). | :The answer lies within the [[TRAM]] files. Each animation which can hurt somebody should have "extents". Extents are invisible boundaries which tell the AI about the range of enemy attacks. There are two types, horizontal and vertical, but the more important thing AI-wise is that, without extents, attack TRAMs will not be registered by AI characters as attacks, so AI will not try to block or dodge them. As long as the attack has extents data, then the AI will have the needed knowledge of the path of the attacking character's body parts (see attack part of [[TRAM]]). | ||
:This info is used by the melee part of AI for defensive purposes (deciding what kind of evasive move to use, and whether to crouch or not) as well as for offensive purposes -- an AI will not execute an attack move unless it sees that the enemy falls within its attack move's extents. | :This info is used by the melee part of AI for defensive purposes (deciding what kind of evasive move to use, and whether to crouch or not) as well as for offensive purposes -- an AI will not execute an attack move unless it sees that the enemy falls within its attack move's extents. | ||