Bevy adapt 3D to 2D

When to use

Load this when a 3D design should render as sprites or billboards. Gameplay components stay. Render components change.

ECS shape

• Draw: replace mesh and PBR material entities' render parts with Sprite where a billboard is enough.
• Camera: use Camera2d from bevy-camera-systems.
• Lights: 3D light entities are not required for an unlit sprite. Do not leave clustered-light assumptions in gameplay code.

What stays and what changes

Piece	Bevy idiom
Gameplay on the actor	Keep the same components. Swap render components for Sprite.
View	Camera2d.
Draw order	A DrawOrder component you store, then write into Transform.

Examples

[dependencies]
bevy = "0.20"

Gameplay components stay on the entity. The 3D render components come off, and a Sprite goes on. Camera2d is the view.

#[derive(Component)]
struct Actor;

#[derive(Component)]
struct DrawOrder(f32);

fn spawn_flat_view(mut commands: Commands) {
    commands.spawn(Camera2d);
}

fn present_as_sprites(
    mut commands: Commands,
    asset_server: Res<AssetServer>,
    actors: Query<(Entity, &DrawOrder), With<Actor>>,
) {
    let image = asset_server.load("actors/hero.png");
    for (entity, order) in &actors {
        commands
            .entity(entity)
            .remove::<Mesh3d>()
            .remove::<MeshMaterial3d<StandardMaterial>>()
            .insert((
                Sprite {
                    image: image.clone(),
                    custom_size: Some(Vec2::new(64.0, 64.0)),
                    ..default()
                },
                Transform::from_xyz(0.0, order.0, 0.0),
            ));
    }
}

A new actor can spawn already flat. The same Actor component is what gameplay systems query.

#[derive(Component)]
struct Actor;