Input & Events

Handle keyboard, mouse, gamepad, and in-game events in Bevy - responsive controls without tangled systems.

Recipe

fn jump(
    keys: Res<ButtonInput<KeyCode>>,
    mut q: Query<&mut PlayerState>,
) {
    if keys.just_pressed(KeyCode::Space) {
        for mut state in &mut q {
            state.request_jump = true;
        }
    }
}

When to reach for this:

• Any player-controlled game
• Replay systems recording input edges
• UI buttons firing gameplay via events
• Multiplayer local couch co-op with multiple gamepads

Working Example

use bevy::prelude::*;
 
#[derive(Event)]
struct PlayerShot {
    entity: Entity,
}
 
#[derive(Component)]
struct Cooldown(Timer);
 
fn shooting(
    mouse: Res<ButtonInput<MouseButton>>,
    mut commands: Commands,
    mut reader_q: Query<(Entity, &mut Cooldown)>,
    mut events: EventWriter<PlayerShot>,
    time: Res<Time>,
) {
    if !mouse.just_pressed(MouseButton::Left) {
        return;
    }
    for (entity, mut cd) in &mut reader_q {
        cd.0.tick(time.delta());
        if cd.0.finished() {
            events.write(PlayerShot { entity });
            cd.0.reset();
        }
    }
}
 
fn on_shot(mut events: EventReader<PlayerShot>) {
    for e in events.read() {
        println!("shot from {:?}", e.entity);
    }
}

What this demonstrates:

• just_pressed edge for single fire per click
• Cooldown timer gating event spam
• EventReader consumer separate from writer system

Deep Dive

How It Works

• Input resources updated once per frame before Update systems.
• Action maps (community leafwing-input-manager or custom) bind keys to intents.
• Events are queues drained by readers; order depends on system ordering.
• UI nodes can block pointer events when interactive.

Input Types

Gotchas

• Using pressed for actions needing once - auto-repeat feel wrong. Fix: just_pressed for discrete actions.
• No delta time on mouse look - sensitivity varies with FPS. Fix: scale by time.delta_secs().
• Systems reading events before writers run - one-frame lag. Fix: order .after(shooting) on reader.
• Thousands of events per frame - overhead. Fix: direct component mutation for bulk sims; events for sparse signals.
• Gamepad not assigned - player 2 idle. Fix: detect Gamepad connections on insert and map per device.

Alternatives

FAQs

Related

• Bevy Engine - system ordering
• Game Loops & Timing - fixed update
• Game Dev Basics - input example
• Physics & Audio - event-driven SFX

Stack versions: This page was written for Rust 1.97.0 (edition 2024), Tokio 1.x, Axum 0.8, serde 1.0, sqlx 0.8, clap 4, and Polars 0.46+.