⚠️ Beta State

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.

Rotation

Rotate a 2D sprite continuously using a custom rotation speed.

Introduction

Rotation in 2D is straightforward — modify the Z-axis rotation of the Transform each frame. This example spins a sprite at a configurable speed.

from pybevy.prelude import *
from math import pi

Rotation Speed Component

@component
class RotationSpeed(Component):
    speed: float = 1.0

Setup

def setup(commands: Commands, asset_server: AssetServer) -> None:
    commands.spawn(Camera2d())
    commands.spawn(
        Sprite.from_image(asset_server.load_image("branding/icon.png")),
        RotationSpeed(speed=pi / 2.0),
    )

Rotation System

Apply rotation each frame using rotate_z() scaled by delta time for frame-rate independence.

def rotate(time: Res[Time], query: Query[tuple[Mut[Transform], RotationSpeed]]) -> None:
    for transform, rotation in query:
        transform.rotate_z(rotation.speed * time.delta_secs())

Running the App

@entrypoint
def main(app: App) -> App:
    return (
        app
        .add_plugins(DefaultPlugins)
        .add_systems(Startup, setup)
        .add_systems(Update, rotate)
    )
 
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.

$pybevy watch rotation.py

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.

Move Sprite

Sprite