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

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

fn main() {
  App::build()
    .add_plugins(DefaultPlugins)
    .add_plugin(PhysicsPlugin::default()) // Add the plugin
    .insert_resource(Gravity::from(Vec3::new(0.0, -9.81, 0.0))) // Optionally define gravity
    .add_startup_system(spawn.system())
    .run();
}

fn spawn(mut commands: Commands) {
    commands

        // Spawn any bundle of your choice. Only make sure there is a `GlobalTransform`
        .spawn_bundle(SpriteBundle::default())

        // Make it a rigid body
        .insert(RigidBody::Dynamic)
        
        // 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() })
        .insert(RotationConstraints::lock())
        .insert(CollisionLayers::none().with_group(Layer::Player).with_mask(Layer::World));
}

// Define your physics layers
#[derive(PhysicsLayer)]
enum Layer {
    World,
    Player,
    Enemies,
}

For a 3d game:

bevy = "^0.5.0"
heron = { version = "0.12.1", features = ["3d"] }

For a 2d game:

bevy = "^0.5.0"
heron = { version = "0.12.1", features = ["2d"] }

• Use bevy types, resources and components when possible (Vec3, Quat, Transform, Events, etc.)
• Provide a single API that works for both 2d and 3d. (Like bevy does)
• Data oriented. Using this library should look like it is part of bevy.
• Avoid asking the user to lookup in resources via handles. Data should be accessible and modifiable directly in components.
• Hide the actual physics engine. This is an implementation detail the user shouldn't have to care about.
  • But, allow advanced users to access the underlying rapier resources, so a user is never blocked by a missing element in the API of heron.

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

• 3d Enable simulation on the 3 axes x, y, and z.
• 2d Enable simulation only on the first 2 axes x and y.
• debug-2d Render 2d collision shapes.
• debug-3d Render 3d collision with wireframes.

bevy_rapier plugin is an excellent option and should definitely be considered.

Here are some key differences between the two projects:

• heron tries to provide a smaller, simpler API that is easier to use. bevy_rapier is more complete and powerful, but a bit more complex.
• heron mostly hides the underlying physics engine, so you don't have to use rapier directly nor nalgebra. bevy_rapier asks the user to deal directly with rapier and nalgebra.
• heron is focused on games only. bevy_rapier targets all kind of physics simulation applications (incl. games).
• bevy_rapier is actively maintained by dimforge, the developer of rapier. heron is also active, but cannot evolve as fast as bevy_rapier can.

heron is probably more suited for simple games and game-jams, where the ease of learn/use is especially valuable and where the lack of advanced feature isn't problematic.

bevy_rapier is probably more suited for bigger/complex games and other types of physics simulations, where it may be better to learn/use a more exhaustive/complex API.

You can open issues/discussions here or you can discuss with me (Jomag#2675) in the bevy discord

See how to contribute