PyBevy is in an early and experimental stage. The API is incomplete, subject to breaking changes without notice, and you should expect bugs. Many features are still under development.
Parenting
Illustrates how to create parent-child relationships between entities and how parent transforms are propagated to their descendants.
from pybevy.prelude import *
# A marker component for rotation
@component
class Rotator(Component):
pass
# System that rotates entities with the Rotator component
def rotator_system(time: Res[Time], query: Query[Mut[Transform], With[Rotator]]) -> None:
for transform in query:
transform.rotate_x(3.0 * time.delta_secs())
# Set up the scene
def setup(
commands: Commands,
meshes: ResMut[Assets[Mesh]],
materials: ResMut[Assets[StandardMaterial]],
) -> None:
cube_handle = meshes.add(Cuboid(2.0, 2.0, 2.0))
cube_material_handle = materials.add(Color.srgb(0.8, 0.7, 0.6))
# Parent cube with Rotator
commands.spawn(
Mesh3d(cube_handle),
MeshMaterial3d(cube_material_handle),
Transform.from_xyz(0.0, 0.0, 1.0),
Rotator(),
).with_children(
lambda parent: parent.spawn(
Mesh3d(cube_handle),
MeshMaterial3d(cube_material_handle),
Transform.from_xyz(0.0, 0.0, 3.0),
)
)
@entrypoint
def main(app: App) -> App:
return app.add_plugins(DefaultPlugins).add_systems(Startup, setup).add_systems(Update, rotator_system)
if __name__ == "__main__":
main().run()Running this example
Use PyBevy's hot reload feature to run and develop this example. If you don't have PyBevy installed, check out the Quick Start guide.
The code will reload automatically when you make changes to the file.
From Python to Rust
Notice how the core concepts in the code—Commands, Assets, App, and Systems—are identical to the original Bevy example?
This is the power of pybevy! It lets you learn Bevy's powerful, data-driven architecture in friendly Python.
When your project grows and you're ready for maximum, native performance, you'll already know the concepts to start writing systems in Bevy Engine with Rust.