auderer / bevy_hanabi

Hanabi — a GPU particle system plugin for the Bevy game engine.

🎆 Bevy Hanabi

🎆 Hanabi — a GPU particle system for the Bevy game engine.

Overview

The Hanabi particle system is a modern GPU-based particle system for the Bevy game engine. It focuses on scale to produce stunning visual effects (VFX) in real time, offloading most of the work to the GPU, with minimal CPU intervention. The design is inspired by modern particle systems found in other industry-leading game engines.

🚧 This project is under heavy development, and is currently lacking both features and performance / usability polish. However, for moderate-size effects, it can already be used in your project. Feedback and contributions on both design and features are very much welcome.

Usage

The 🎆 Bevy Hanabi plugin is compatible with Bevy versions >= 0.6; see Compatible Bevy versions.

Add the dependency

Add the bevy_hanabi dependency to Cargo.toml:

[dependencies]
bevy_hanabi = "0.4"

See also Features below for the list of supported features.

System setup

Add the HanabiPlugin to your app:

use bevy_hanabi::prelude::*;

App::default()
    .add_plugins(DefaultPlugins)
    .add_plugin(HanabiPlugin)
    .run();

Create a particle effect

Create an EffectAsset describing a visual effect:

fn setup(mut effects: ResMut<Assets<EffectAsset>>) {
    // Define a color gradient
    let mut gradient = Gradient::new();
    gradient.add_key(0.0, Vec4::new(1., 0., 0., 1.)); // Red
    gradient.add_key(1.0, Vec4::ZERO); // Transparent black

    // Create the effect asset
    let effect = effects.add(EffectAsset {
            name: "MyEffect".to_string(),
            // Maximum number of particles alive at a time
            capacity: 32768,
            // Spawn at a rate of 5 particles per second
            spawner: Spawner::rate(5.0.into()),
            ..Default::default()
        }
        // On spawn, randomly initialize the position and velocity
        // of the particle over a sphere of radius 2 units, with a
        // radial initial velocity of 6 units/sec away from the
        // sphere center.
        .init(PositionSphereModifier {
            center: Vec3::ZERO,
            radius: 2.,
            dimension: ShapeDimension::Surface,
            speed: 6.0.into(),
        })
        // Every frame, add a gravity-like acceleration downward
        .update(AccelModifier {
            accel: Vec3::new(0., -3., 0.),
        })
        // Render the particles with a color gradient over their
        // lifetime.
        .render(ColorOverLifetimeModifier { gradient })
    );
}

Add a particle effect

Use a ParticleEffectBundle to create an effect instance from an existing asset:

commands
    .spawn_bundle(ParticleEffectBundle {
        effect: ParticleEffect::new(effect),
        transform: Transform::from_translation(Vec3::new(0., 1., 0.)),
        ..Default::default()
    });

Examples

See the examples/ folder.

Gradient

Animate an emitter by moving its Transform component, and emit textured quad particles with a ColorOverLifetimeModifier.

cargo run --example gradient --features="bevy/bevy_winit bevy/bevy_pbr bevy/png 3d"

Force Field

This example demonstrates the force field modifier ForceFieldModifier, which allows creating some attraction and repulsion sources affecting the motion of the particles.

cargo run --example force_field --features="bevy/bevy_winit bevy/bevy_pbr 3d"

2D

This example shows how to use 🎆 Hanabi with a 2D camera.

cargo run --example 2d --features="bevy/bevy_winit bevy/bevy_sprite 2d"

Activate

This example demonstrates manual activation and deactivation of a spawner, from code (CPU). The circle bobs up and down in the water, spawning square bubbles when in the water only.

cargo run --example activate --features="bevy/bevy_winit bevy/bevy_pbr 3d"

Spawn

This example demonstrates three spawn modes:

• Left: Continuous emission with a fixed rate (particles/second).
• Center: One-shot burst emission of a fixed count of particles.
• Right: Continuous bursts of particles, an hybrid between the previous two.

It also shows the applying of constant force (downward gravity-like, or upward smoke-style).

cargo run --example spawn --features="bevy/bevy_winit bevy/bevy_pbr 3d"

Spawn on Command

This example demonstrates how to emit a burst of particles when an event occurs. This gives total control of the spawning to the user code.

cargo run --example spawn_on_command --features="bevy/bevy_winit bevy/bevy_pbr 3d"

Circle

This example demonstrates the circle spawner type, which emits particles along a circle perimeter or a disk surface. This allows for example simulating a dust ring around an object colliding with the ground.

cargo run --example circle --features="bevy/bevy_winit bevy/bevy_pbr bevy/png 3d"

Random

This example spawns particles with randomized parameters.

cargo run --example random --features="bevy/bevy_winit bevy/bevy_pbr 3d"

Lifetime

This example demonstrates particle effects with different lifetimes.

cargo run --example lifetime --features="bevy/bevy_winit bevy/bevy_pbr 3d"

Billboard

This example demonstrates particles with the billboard render modifier, making them always face the camera.

cargo run --example billboard --features="bevy/bevy_winit bevy/bevy_pbr bevy/png 3d"

The image on the left has the BillboardModifier enabled.

Feature List

• Spawn
  • Constant rate
  • One-time burst
  • Repeated burst
  • Spawner resetting
  • Spawner activation/deactivation
  • Randomized spawning parameters
• Initialize
  • Constant position
  • Position over shape
    • cube
    • circle
    • sphere
    • cone / truncated cone (3D)
    • plane
    • generic mesh / point cloud (?)
  • Random position offset
  • Constant velocity
  • Random velocity
  • Constant color
  • Random color
• Update
  • Motion integration
  • Apply forces
    • Constant (gravity)
    • Force field
  • Collision
    • Shape
      • plane
      • cube
      • sphere
    • Depth buffer
  • Lifetime
  • Size change over lifetime
  • Color change over lifetime
• Render
  • Quad
    • Textured
  • Generic 3D mesh
  • Deformation
    • Velocity (trail)
  • Camera support
    • 2D cameras (Camera2dBundle) only
    • 3D cameras (Camera3dBundle) only
    • Simultaneous dual 2D/3D cameras
  • Face camera (Billboard)
  • Face constant direction
• Debug
  • GPU debug labels / groups
  • Debug visualization
    • Position magnitude
    • Velocity magnitude
    • Age / lifetime

Features

🎆 Bevy Hanabi supports the following cargo features:

Feature	Default	Description
2d	✔	Enable rendering through 2D cameras (Camera2dBundle)
3d	✔	Enable rendering through 3D cameras (Camera3dBundle)

For optimization purpose, users of a single type of camera can disable the other type by skipping default features in their Cargo.toml. For example to use only the 3D mode:

bevy_hanabi = { version = "0.4", default-features = false, features = [ "3d" ] }

Compatible Bevy versions

The main branch is compatible with the latest Bevy release.

Compatibility of bevy_hanabi versions:

bevy_hanabi	bevy
0.3-0.4	0.8
0.2	0.7
0.1	0.6