Skills (Action Nodes)

Skills are the leaf nodes of a behavior tree that perform concrete actions. In our system, calling a skill function in Rhai creates an ActionNode, which is a type of BehaviorNode.

Dynamic Arguments

Many skills accept dynamic arguments. This means that instead of providing a fixed, static value, you can provide a callback function. This function will be executed by the behavior tree on each tick to determine the value for that argument dynamically.

A callback function always receives the RobotSituation object (usually named s) as its only parameter, giving you access to the full world state to make decisions.

Example:

#![allow(unused)]
fn main() {
// Static argument
GoToPosition(vec2(100.0, 200.0))

// Dynamic argument using a callback
fn get_ball_pos(s) {
    return s.world.ball.position;
}
GoToPosition(get_ball_pos)
}

This allows for creating highly reactive and flexible behaviors.

`GoToPosition`

Moves the robot to a target position.

Syntax: GoToPosition(target: Vec2 | FnPtr, [options: Map], [description: String]) -> BehaviorNode

Parameters:

target: The target position. Can be a static Vec2 (created with vec2(x, y)) or a callback function that returns a Vec2.
options (optional): A map with optional parameters. Any of these can also be dynamic callbacks.
- heading (Float | FnPtr): The final heading of the robot in radians.
- with_ball (Bool | FnPtr): If true, the robot will try to keep the ball while moving.
- avoid_ball (Bool | FnPtr): If true, the robot will actively try to avoid the ball while moving.
description (optional): A string description for debugging.

Example (Static):

#![allow(unused)]
fn main() {
// Go to a fixed position with a fixed heading.
GoToPosition(
    vec2(0.0, 0.0),
    #{ heading: 1.57, with_ball: true },
    "Go to center with ball"
)
}

Example (Dynamic):

#![allow(unused)]
fn main() {
fn get_ball_pos(s) {
    return s.world.ball.position;
}

fn get_heading_towards_goal(s) {
    let goal_pos = vec2(6000.0, 0.0);
    // Assumes a 'angle_to' helper exists
    return s.player.position.angle_to(goal_pos);
}

// Go towards the ball, while always facing the opponent's goal.
GoToPosition(
    get_ball_pos,
    #{ heading: get_heading_towards_goal, avoid_ball: false },
    "Follow ball while facing goal"
)
}

`FaceAngle`

Rotates the robot to face a specific angle.

Syntax: FaceAngle(angle: Float | FnPtr, [options: Map], [description: String]) -> BehaviorNode

Parameters:

angle: The target angle in radians. Can be a static Float or a callback function that returns a Float.
options (optional): A map with the following keys:
- with_ball (Bool | FnPtr): If true, the robot will try to keep the ball while turning.
description (optional): A string description for debugging.

`FaceTowardsPosition`

Rotates the robot to face a specific world position.

Syntax: FaceTowardsPosition(target: Vec2 | FnPtr, [options: Map], [description: String]) -> BehaviorNode

Parameters:

target: The target position to face. Can be a static Vec2 or a callback function that returns a Vec2.
options (optional): A map with with_ball (Bool | FnPtr).
description (optional): A string description for debugging.