⚠️ 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.

Animated Transform

Animate an entity's position, rotation, and scale over time.

Introduction

Transform animation is fundamental to any game. This example animates position, rotation, and scale using sine waves for smooth oscillation.

from pybevy.prelude import *
import math

Setup

def setup(
    commands: Commands,
    meshes: ResMut[Assets[Mesh]],
    materials: ResMut[Assets[StandardMaterial]],
) -> None:
    commands.spawn(
        Mesh3d(meshes.add(Cuboid.from_length(1.0))),
        MeshMaterial3d(materials.add(Color.srgb(0.3, 0.5, 0.9))),
        Transform.from_xyz(0.0, 0.5, 0.0),
    )
    commands.spawn(PointLight(shadows_enabled=True), Transform.from_xyz(4.0, 8.0, 4.0))
    commands.spawn(Camera3d(), Transform.from_xyz(-3.0, 3.0, 5.0).looking_at(Vec3.ZERO, Vec3.Y))

Animation System

Apply sine-wave animations to translation, rotation, and scale simultaneously.

def animate(time: Res[Time], query: Query[Mut[Transform], With[Mesh3d]]) -> None:
    t = time.elapsed_secs()
    for transform in query:
        transform.translation.y = 0.5 + math.sin(t * 2.0) * 1.5
        transform.rotate_y(time.delta_secs())
        scale = 1.0 + 0.3 * math.sin(t * 3.0)
        transform.scale = Vec3.splat(scale)

Running the App

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

Wireframe

Color Animation

animation