Bevy Genre Sports Agent Skill

Bevy Sports (thin router)

Genre router. Domain work lives in the Bevy skills below.

When to use

Load this for match clock, teams, and ball entities you define.

ECS shape

• Components hold the genre's per-entity flags as plain data. This file does not name new engine types.
• Resources hold run-wide counters (score, wave index, seed) via bevy-data-resources.
• Systems read those components on Update or the fixed timestep from bevy-master. Order them with .chain() when a later system must see the result.
• Schedule: gameplay mode changes go through bevy-state-machines. Do not invent a genre plugin.

Routing

• bevy-game-loop-time-trial - Match clock.
• bevy-combat-system - Contact if the sport uses hits.
• bevy-character-movement - Athletes.
• bevy-state-machines - Period state.

Scope

Match clock, score, possession, and formation targets are components and one resource. A rigid-body ball solver stays on the physics skill once one is chosen.

Examples

[package]
name = "sports"
version = "0.1.0"
edition = "2021"

[dependencies]
bevy = "0.20"

The clock and score are one resource. Period changes after the clock step in the same chain.

#[derive(Clone, Copy, PartialEq, Eq)]
enum Period {
    Kickoff,
    Playing,
    Goal,
    FullTime,
}

#[derive(Resource)]
struct Match {
    period: Period,
    seconds_left: f32,
    score_a: u32,
    score_b: u32,
}

fn tick_match(time: Res<Time<Fixed>>, mut game: ResMut<Match>) {
    if game.period != Period::Playing {
        return;
    }
    game.seconds_left = (game.seconds_left - time.delta_secs()).max(0.0);
    if game.seconds_left == 0.0 {
        game.period = Period::FullTime;
    }
}

fn score_goal(team_a: bool, game: &mut Match) {
    if team_a {
        game.score_a += 1;
    } else {
        game.score_b += 1;
    }
    game.period = Period::Goal;
}

pub struct MatchPlugin;

impl Plugin for MatchPlugin {
    fn build(&self, app: &mut App) {
        app.insert_resource(Match {
            period: Period::Kickoff,
            seconds_left: 300.0,
            score_a: 0,
            score_b: 0,
        })
        .add_systems(FixedUpdate, tick_match);
    }
}

Athletes seek a slot. Only the presser chases the ball; the rest hold formation so the side does not bunch.

#[derive(Component)]
struct Athlete {
    speed: f32,
    presses: bool,
}

#[derive(Component)]
struct Slot {
    offset: Vec3,
}

#[derive(Component)]
struct Ball;

fn hold_formation(
    time: Res<Time<Fixed>>,
    ball: Query<&Transform, With<Ball>>,
    slots: Query<&Slot>,
    mut athletes: Query<(&Athlete, &mut Transform), Without<Ball>>,
) {
    let Ok(ball_tf) = ball.single() else {
        return;
    };
    let dt = time.delta_secs();
    for (athlete, mut transform) in &mut athletes {
        let mut target = ball_tf.translation;
        if !athlete.presses {
            if let Some(slot) = slots.iter().next() {
                target += slot.offset;
            }
        }
        let delta = target - transform.translation;
        let step = athlete.speed * dt;
        if delta.length() > step {
            transform.translation += delta.normalize() * step;
        } else {
            transform.translation = target;
        }
    }
}

The action key passes when the controlled athlete has the ball, and takes the ball when that athlete is close.

#[derive(Component)]
struct Controlled;

#[derive(Component)]
struct HasBall;

#[derive(Component)]
struct Athlete {
    speed: f32,
    presses: bool,
}

#[derive(Component)]
struct Ball;

fn contextual_action(
    keys: Res<ButtonInput<KeyCode>>,
    ball: Query<&Transform, With<Ball>>,
    mut athletes: Query<(Entity, &Transform, Has<HasBall>, Has<Controlled>), With<Athlete>>,
    mut commands: Commands,
) {
    if !keys.just_pressed(KeyCode::KeyJ) {
        return;
    }
    let Ok(ball_tf) = ball.single() else {
        return;
    };
    for (entity, transform, has_ball, controlled) in &mut athletes {
        if !controlled {
            continue;
        }
        if has_ball {
            commands.entity(entity).remove::<HasBall>();
        } else if transform.translation.distance(ball_tf.translation) < 1.5 {
            commands.entity(entity).insert(HasBall);
        }
    }
}

Kickoff places two athletes, one slot, and the ball.

#[derive(Component)]
struct Athlete {
    speed: f32,
    presses: bool,
}

#[derive(Component)]
struct Controlled;

#[derive(Component)]
struct Slot {
    offset: Vec3,
}

#[derive(Component)]
struct Ball;

fn spawn_kickoff(mut commands: Commands) {
    commands.spawn((
        Athlete {
            speed: 6.0,
            presses: true,
        },
        Controlled,
        Transform::from_xyz(-2.0, 0.0, 0.0),
    ));
    commands.spawn((
        Athlete {
            speed: 5.0,
            presses: false,
        },
        Transform::from_xyz(-8.0, 0.0, 2.0),
    ));
    commands.spawn((
        Slot {
            offset: Vec3::new(-6.0, 0.0, 4.0),
        },
        Transform::default(),
    ));
    commands.spawn((Ball, Transform::from_xyz(0.0, 0.4, 0.0)));
}

Expert Knowledge Delta

Target: Bevy 0.20+.

Core ECS types: Component, Resource, Query, Commands, Startup, Update, Fixed / FixedMain (bevy::time), .chain(), Plugin, DefaultPlugins, MinimalPlugins. Messages and observers are an ownership slot. See bevy-events-messaging for their APIs. Systems run in parallel unless .chain() orders the ones that conflict.

Who owns state

| Piece | Owner | Who may mutate | Schedule |

| --- | --- | --- | --- |

| Data on one entity | Component | One system via Query | Update or FixedMain |

| One value for the whole app | Resource | One system | Startup to insert, then the schedule that reads it |

| Spawn | Commands | The spawning system | Startup for the initial world; later schedules for runtime spawn |

| Order that must not race | .chain() | The chained systems only | Same schedule |

| Plugin boundary | Plugin | build registers systems and resources | Before the app runs |

Borrow rule: two systems that both mutably query the same component must be ordered (.chain()) or split so only one writes. Unrelated systems stay parallel. That is the ECS page rule, not a guess at a system-set API.

Decision

| If you need | Do this | Do not |

| --- | --- | --- |

| Per-entity data | Component + Query | A Godot node script |

| App-wide config or clock | Resource | Copy the value onto every entity |

| Stable simulation step | FixedMain and the Fixed clock | Tie simulation to raw frame Update |

| Startup spawn | Commands in Startup | Spawn from a render system |

| Cross-system notice that is not shared state | Message or observer slot in bevy-events-messaging | A new event type invented in this file |

| An API outside the documented set | Check the official docs first | A made-up crate or API |

Load references/ecs-ownership.md for the ownership table.

NEVER

• Do not pin /0.20.0/ in docs URLs. WHY: links stay on latest; the 0.20 target is stated once in prose.
• Do not mutably query the same component from two unordered systems. WHY: the schedule runs systems in parallel unless .chain() orders them.
• Do not invent a physics, navigation, networking, or XR crate here. WHY: this skill only names documented Bevy crates and modules.

• No Godot types in Bevy code. WHY: Bevy code stays idiomatic ECS and uses only documented Bevy APIs.
• No invented genre APIs. WHY: Bevy code stays idiomatic ECS and uses only documented Bevy APIs.
• Do not pick a physics or net crate here. WHY: Bevy code stays idiomatic ECS and uses only documented Bevy APIs.

Reference

The library pin on bevy-master stays 0.20.0. Official pages stay on the unversioned latest branch.

Official Documentation

• Assets - Official asset catalog. No third-party crate was selected.
• Examples - Example tree on the latest branch.
• ECS - Component, systems, Query, Startup, Update, and .chain().
• Plugins - Plugin, DefaultPlugins, MinimalPlugins, and add_plugins.

Related Skills

Prerequisites

• bevy-master - ECS ownership and schedules.
• bevy-ecs-composition - Spawn and query shape.

Complements

• godot-genre-sports - Sports on the Godot engine, same depth.
• bevy-game-loop-time-trial - Match clock.
• bevy-combat-system - Contact if the sport uses hits.
• bevy-character-movement - Athletes.
• bevy-state-machines - Period state.

Downstream / consumers

• None. This router does not own a second implementation.

Master

• bevy-master - Bevy router.