View source for Example of NextBot Behaviors

The [[NextBot]] AI system uses an "Intention" factor to choose the "Behavior" of an AI-controlled actor, which in turn runs a series of "Actions" for the actor to perform.

This page is meant to show a visual representation of how the Intention factor works in-game, as we look at a round of [[Team Fortress 2]] with nothing but [[bots]]. The example map we will work with is koth_badlands; a map with a single "control point" in the center which the bots will attempt to capture and defend.

The <code>nb_debug</code> console command is what's used to actually see what events, behaviors and actions the bot has in mind. For this example round, we will use <code>nb_debug BEHAVIOR</code>.

= Capturing the point =
[[Image:Nextbot_ex_behavior1.JPG|thumb|300px|right|The behavior of a Soldier bot, as shown with <code>nb_debug BEHAVIOR</code>.]]As the round begins, this red Soldier bot has already chosen its behavior and actions. Let's take a closer look as to what these actions actually are:

=== MainAction ===
This is the root of the bot's actions, as all child actions are stored within this one action.

=== TacticalMonitor ===
This handles what the bot actually wants to do. In this example, the '''TacticalMonitor''' is telling the Soldier bot to look at its '''ScenarioMonitor'''.

=== ScenarioMonitor ===
This handles how a bot manages certain situations regarding either its class or the map's gamemode. In this example, the '''ScenarioMonitor''' is telling the Soldier bot to '''CapturePoint'''. '''ScenarioMonitor''' examples for specific classes can be found below.

=== CapturePoint ===
This the actual AI code the Soldier bot needs to be doing. In this example, the '''CapturePoint''' is telling the Soldier bot to move towards and capture the central control point.


With these actions in mind, the Soldier bot's current thinking process is '''''MainAction > TacticalMonitor > ScenarioMonitor > CapturePoint'''''.

= Defending the point =
[[Image:Nextbot_ex_behavior3.JPG|thumb|300px|right|The Scout bot's "DefendPoint" action leads to a child "BlockCapture" action.]]Let's say that the Soldier bot managed to successfully capture the point. Now what would the process look like?
[[Image:Nextbot_ex_behavior4.JPG|thumb|300px|right|The Soldier bot's "TacticalMonitor" is now telling it to "RetreatToCover".]]
Surprisingly, only one action changes. The previous '''CapturePoint''' action has been replaced with '''DefendPoint''', which is simply telling the Soldier bot to defend the point it just captured. The Soldier bot's thinking process is now '''''MainAction > TacticalMonitor > ScenarioMonitor > DefendPoint'''''.

=== Combat ===
Unfortunately, while the Soldier bot wasn't paying attention, a pesky blue Scout bot managed to reach the point and capture it. Now the red Soldier bot needs to '''CapturePoint''' once more, but the Scout bot is interfering with its action. Once the two bots see each other, both of their actions change.

==== Scout's actions ====
Let's take a look at the Scout bot's actions first. Before it saw the enemy bot, the Scout's thinking process was '''''MainAction > TacticalMonitor > ScenarioMonitor > DefendPoint'''''. Now that the two bots have seen each other, the Scout bot needs to make sure that the Soldier bot doesn't capture its point. With this scenario in mind, the Scout bot's '''DefendPoint''' action initializes a new child action called '''BlockCapture''', which will tell the Scout bot to move to its point so that it will stop the Soldier bot from capturing. The Scout bot's current thinking process is now '''''MainAction > TacticalMonitor > ScenarioMonitor > DefendPoint > BlockCapture'''''.

==== Soldier's actions ====
The Soldier bot needs to '''CapturePoint''', but it isn't going to just leap blindly into battle. For once, the Soldier's '''TacticalMonitor''' has changed, telling it to '''RetreatToCover'''. Because of this new child action, the Soldier bot is forced to retreat until the Scout bot is either dead or nowhere nearby. Once the Scout bot is no longer a threat, the Soldier bot will return to its initial '''CapturePoint''' action. The Soldier bot's thinking process for this scenario is '''''MainAction > TacticalMonitor > RetreatToCover'''''.

==== Death ====
During its fight with the Scout bot, the Soldier bot has accidentally killed both itself and the Scout bot by shooting a rocket at point-blank. Both bots run a '''Dead''' action, which prevents them from doing anything until they have respawned. The thinking process for both bots is simply '''''Dead'''''.

= Class-specific actions =
[[Image:Nextbot_ex_behavior6.JPG|thumb|300px|right|The Engineer bot's "ScenarioMonitor" is "EngineerBuild" instead of "CapturePoint". The bot's objective is "EngineerMoveToBuild".]]As mentioned earlier, the '''ScenarioMonitor''' manages both the bot's class and the gamemode the map is on. Let's take a look at what some different classes have for their '''ScenarioMonitor'''.
[[Image:Nextbot_ex_behavior7.JPG|thumb|300px|right|The Spy bot's objective is "SpyInfiltrate". Since it has seen the Engineer bot, its now ready to "SpyAttack".]]
=== Engineer ===
This red Engineer bot is not interested in '''CapturePoint''', unlike the Soldier bot. Instead, the Engineer wants to '''EngineerBuild''' in order to defend the point. Having chosen a location to build its contraptions, the Engineer bot's '''EngineerBuild''' action initializes a child action called '''EngineerMoveToBuild'''. This new child action tells the Engineer bot to move to wherever it wants to build; in this case the location is right next to the control point. The Engineer bot's thinking process is '''''MainAction > TacticalMonitor > ScenarioMonitor > EngineerBuild > EngineerMoveToBuild'''''.

=== Sniper ===
A blue Sniper bot has joined the battle, and like the Engineer, it isn't interested in '''CapturePoint'''. The Sniper bot's '''ScenarioMonitor''' is instead telling it to '''SniperLurk''', in which the Sniper bot goes hunting for certain sniper spots. The Sniper bot's thinking process is '''''MainAction > TacticalMonitor > ScenarioMonitor > SniperLurk'''''.

=== Spy ===
Like the Engineer and Sniper bots, the blue Spy bot isn't looking for a point to capture. With '''SpyInfiltrate''', the Spy bot is wandering into the enemy base in hopes that there is something it can do. Once it finds the enemy Engineer bot, the Spy bot prepares itself for a backstab by initializing a child action called '''SpyAttack'''. The Spy bot's thinking process is '''''MainAction > TacticalMonitor > ScenarioMonitor > SpyInfiltrate > SpyAttack'''''.













= See also =
[[NextBot]]

[[nb_debug]]

[[Category:NextBot]]