Function fall

examples/input.rs:103–109

(mut fallings: Query<(&mut Transform, &mut Falling)>, time: Res<Time>)

const GRAVITY: f32 = -1000.;

fn fall(mut fallings: Query<(&mut Transform, &mut Falling)>, time: Res<Time>) {
    for (mut transform, mut falling) in &mut fallings {
        let dt = time.delta_secs();
        falling.velocity += dt * GRAVITY;
        transform.translation.y += dt * falling.velocity;
    }
}