acts-of-gods/src/editor.rs

use crate::prelude::*;

pub(crate) struct EditorPlugin;

impl Plugin for EditorPlugin {
    fn build(&self, app: &mut App) {
        app.init_state::<EditorState>()
            .add_systems(Startup, init_editor)
            .add_systems(
                Update,
                toggle_editor_state.run_if(input_just_pressed(KeyCode::F3)),
            )
            .add_systems(
                OnTransition {
                    from: EditorState::Open,
                    to: EditorState::Closed,
                },
                toggle_editor_window,
            )
            .add_systems(
                OnTransition {
                    from: EditorState::Closed,
                    to: EditorState::Open,
                },
                toggle_editor_window,
            )
            .add_systems(
                Update,
                handle_window_close.run_if(on_event::<WindowCloseRequested>()),
            );
    }
}

/// Tracking the open/closed state of the editor
#[derive(States, Debug, Clone, PartialEq, Eq, Hash, Default, Component)]
enum EditorState {
    /// The editor is closed => the editor window is disabled
    #[default]
    Closed,
    /// The editor is open => the editor window is visible
    Open,
}

impl std::ops::Not for &EditorState {
    type Output = EditorState;

    fn not(self) -> Self::Output {
        match self {
            EditorState::Open => EditorState::Closed,
            EditorState::Closed => EditorState::Open,
        }
    }
}

impl std::convert::From<&EditorState> for bool {
    fn from(value: &EditorState) -> bool {
        match value {
            EditorState::Open => true,
            EditorState::Closed => false,
        }
    }
}

/// Tag component for editor entities
#[derive(Component)]
struct EditorTag;

/// At startup initialize some editor components
fn init_editor(mut commands: Commands) {
    // Editor window
    let editor_window = commands
        .spawn((
            EditorTag,
            Window {
                visible: false,
                title: "Editor".into(),
                ..default()
            },
        ))
        .id();

    // Editor camera
    let editor_camera = commands
        .spawn((
            EditorTag,
            Camera3dBundle {
                camera: Camera {
                    target: RenderTarget::Window(WindowRef::Entity(editor_window)),
                    ..default()
                },
                ..default()
            },
        ))
        .id();

    // Editor UI elements
    commands
        .spawn((
            EditorTag,
            TargetCamera(editor_camera),
            NodeBundle { ..default() },
        ))
        .with_children(|parent| {
            parent.spawn((
                EditorTag,
                TextBundle::from_section(
                    "Welcome to the editor",
                    TextStyle {
                        color: Color::WHITE,
                        ..default()
                    },
                ),
            ));
        });
}

fn toggle_editor_state(
    curr_state: Res<State<EditorState>>,
    mut next_state: ResMut<NextState<EditorState>>,
    keys: Res<ButtonInput<KeyCode>>,
    mut catch: Local<bool>,
) {
    if keys.pressed(KeyCode::F3) && !*catch {
        *catch = true;
        match curr_state.get() {
            EditorState::Open => next_state.set(EditorState::Closed),
            EditorState::Closed => next_state.set(EditorState::Open),
        }
    } else {
        *catch = false;
    }
}

fn toggle_editor_window(
    state: Res<State<EditorState>>,
    mut windows: Query<&mut Window, With<EditorTag>>,
    mut cameras: Query<&mut Camera, With<EditorTag>>,
) {
    let curr = state.get().into();
    cameras.iter_mut().for_each(|mut camera| {
        camera.is_active = curr;
    });
    windows.iter_mut().for_each(|mut window| {
        window.visible = curr;
    })
}

/// Handles window close requests which are only weird because of the editor
/// When the editor window closes, just make it invisible and change the editor state to "Closed".
fn handle_window_close(
    mut events: EventReader<WindowCloseRequested>,
    editor_windows: Query<Entity, With<EditorTag>>,
    mut editor_state: ResMut<NextState<EditorState>>,
) {
    events
        .read()
        // Filter events down to jus those affecting the editor window
        .filter_map(|WindowCloseRequested { window }| editor_windows.get(*window).ok())
        // For each related close event, send out a "Close the editor" state transition
        .for_each(|_| {
            editor_state.set(EditorState::Closed);
        });
}