rust drag&drop sprites

draganddrop.rs

fn handle_mouse_interactions(
    button_input: Res<Input<MouseButton>>,
    windows: Res<Windows>,
    mut interactables: Query<(Entity, &mut Interactable)>,
    sprites: Query<(Entity, &GlobalTransform), With<Sprite>>,
    rapier_context: Res<RapierContext>,
) {
    //Sequence note: This happens first because we want to know if the mouse button was released event outside our window.

    if button_input.just_released(MouseButton::Left) {
        for (ent, mut interactable) in interactables.iter_mut() {
            match *interactable {
                Interactable::None => (),
                Interactable::Hovering => (),
                Interactable::Dragging { offset, start_pos } => {
                    println!("Drag ended {ent:?}.");
                    *interactable = Interactable::None; //TODO:: Drag ended.
                }
                Interactable::Returning => (),
            }
        }
    }

    let Some(window) = windows.get_primary() else {return;};
    let Some(cursor_point_system) = window.cursor_position() else {return;};
    let cursor_point_game = helpers::get_window_relative_cursor_pos(&window);

    let mut max = f32::NEG_INFINITY;
    let mut res: Option<(Entity, &GlobalTransform)> = None;
    rapier_context.intersections_with_point(cursor_point_game, QueryFilter::default(), |x| {
        let Ok((ent, xform,)) = sprites.get(x) else {return true};

        let ord = xform.translation().z;

        if ord >= max {
            res = Some((ent, xform));
            max = ord;
        }
        true
    });

    if res.is_none() {
        return;
    }

    let (hit_ent, xform) = res.unwrap();

    let Ok((ent, mut interactable)) = interactables.get_mut(hit_ent) else {return};

    match *interactable {
        Interactable::None => {
            //Begin Hovering.
            *interactable = Interactable::Hovering; //TODO:: Hover Begin
        }
        Interactable::Hovering => {
            if button_input.just_pressed(MouseButton::Left) {
                let position = xform.translation();
                let sprite_position = position.truncate();
                let cursor_offset = sprite_position - cursor_point_system;
                //Begin Drag
                println!("Drag started {ent:?}");
                *interactable = Interactable::Dragging {
                    offset: cursor_offset,
                    start_pos: position,
                }; //TODO:: Drag Begin
            }
        }
        Interactable::Dragging { offset, start_pos } => (), //Dragging Action
        Interactable::Returning => (),
    }

    //Second attempt to use iterated iterator.
    for (ent, mut iter_interact) in interactables.iter_mut() {
        if (*interactable != *iter_interact) {
            //do stuff
        }
    }
}