Crate heron[][src]

Expand description

An ergonomic physics API for 2d and 3d bevy games. (powered by rapier)

Get started

Add the dependency and choose to work with either 2d or 3d

Add the library to Cargo.toml.

For a 3d game:

heron = { version = "0.12.1", features = ["3d"] }

For as 2d game:

heron = { version = "0.12.1", features = ["2d"] }

Feature flags

One must choose to use either 2d or 3d. If none of theses two features is enabled, the plugin won’t be available.

  • 3d Enable simulation on the 3 axes x, y, and z. Incompatible with the feature 2d.
  • 2d Enable simulation only on the first 2 axes x and y. Incompatible with the feature 3d, therefore require to disable the default features.
  • debug-2d Render 2d collision shapes. Works only in 2d, support for 3d may be added later.

Install the plugin

The PhysicsPlugin should be installed to enable physics and collision detection.

use bevy::prelude::*;
use heron::prelude::*;

fn main() {
    // ... Add your resources and systems

Create rigid bodies

To create a rigid body, add the RigidBody to the entity and add a collision shapes with the CollisionShape component.

The position and rotation are defined by the bevy GlobalTransform component.

fn spawn(mut commands: Commands) {

    // Spawn any bundle of your choice. Only make sure there is a `GlobalTransform`

    // Make it a rigid body

    // Attach a collision shape
    .insert(CollisionShape::Sphere { radius: 10.0 })

    // Optionally add other useful components...
    .insert(Velocity::from_linear(Vec3::X * 2.0))
    .insert(Acceleration::from_linear(Vec3::X * 1.0))
    .insert(PhysicMaterial { friction: 1.0, density: 10.0, ..Default::default() })

Move rigid bodies programmatically

When creating games, it is often useful to interact with the physics engine and move bodies programmatically. For this, you have two options: Updating the Transform or applying a Velocity.

Option 1: Update the Transform

For positional kinematic bodies (RigidBody::KinematicPositionBased), if the transform is updated, the body is moved and get an automatically calculated velocity. Physics rules will be applied normally. Updating the transform is a good way to move a kinematic body.

For other types of bodies, if the transform is updated, the rigid body will be teleported to the new position/rotation, ignoring physic rules.

Option 2: Use the Velocity component

For RigidBody::Dynamic and RigidBody::KinematicVelocityBased bodies only, one can add a Velocity component to the entity, that will move the body over time. Physics rules will be applied normally.

Note that the velocity component is updated by heron to always reflects the current velocity.

Defining/updating the velocity is a good way to interact with dynamic bodies.

See also



Re-exports of the most commons/useful types

Physics behavior powered by rapier


Utility traits and extensions


Component that defines the linear and angular acceleration.

An axis-angle representation

Collision data concerning one of the two entity that collided

Components that defines the collision layers of the collision shape.

Plugin that registers stage resources and components.

Resource that defines world’s gravity.

Component that defines the physics properties of the rigid body

Plugin to install to enable collision detection and physics behavior.

Resource to control how many physics steps are performed per second.

Resource that controls the physics time scale

Component that restrict what rotations can be caused by forces.

Mark the CollisionShape of the same entity as being a sensor.

Component that defines the linear and angular velocity.


An event fired when the collision state between two entities changed

Components that defines the collision shape of a rigid body

The duration of time that this physics step should advance the simulation time

Physics system labels

Component that mark the entity as being a rigid body


Describes a collision layer


Run criteria system that decides if the physics systems should run.

Derive Macros