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

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

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.