outfly/src/hud.rs

//   ▄████████▄      +        ███ +  ▄█████████ ███     +
//  ███▀    ▀███ +         +  ███    ███▀  +    ███ +       +
//  ███  +   ███ ███   ███ █████████ ███        ███  ███   ███
//  ███     +███ ███   ███    ███    ███▐██████ ███  ███   ███
//  ███ +    ███ ███+  ███   +███    ███     +  ███  ███ + ███
//  ███▄    ▄███ ███▄  ███    ███ +  ███  +     ███  ███▄  ███
//   ▀████████▀ + ▀███████    ███▄   ███▄       ▀████ ▀███████
//       +                  +                +             ███
//  +   ▀████████████████████████████████████████████████████▀
//
// This module manages the heads-up display and augmented reality overlays.

use crate::{actor, audio, camera, chat, nature, skeleton, var};
use bevy::prelude::*;
use bevy::diagnostic::{DiagnosticsStore, FrameTimeDiagnosticsPlugin};
use bevy::transform::TransformSystem;
use bevy_xpbd_3d::prelude::*;
use bevy::math::DVec3;
use std::collections::VecDeque;
use std::time::SystemTime;

pub const HUD_REFRESH_TIME: f32 = 0.1;
pub const FONT: &str = "fonts/Yupiter-Regular.ttf";
pub const LOG_MAX_TIME_S: f64 = 30.0;
pub const LOG_MAX_ROWS: usize = 30;
pub const LOG_MAX: usize = LOG_MAX_ROWS;
pub const MAX_CHOICES: usize = 10;
pub const AMBIENT_LIGHT: f32 = 0.0; // Space is DARK
pub const AMBIENT_LIGHT_AR: f32 = 30.0;
//pub const REPLY_NUMBERS: [char; 10] = ['❶', '❷', '❸', '❹', '❺', '❻', '❼', '❽', '❾', '⓿'];
//pub const REPLY_NUMBERS: [char; 10] = ['①', '②', '③', '④', '⑤', '⑥', '⑦', '⑧', '⑨', '⑩'];
pub const REPLY_NUMBERS: [char; 10] = ['➀', '➁', '➂', '➃', '➄', '➅', '➆', '➇', '➈', '➉'];

pub struct HudPlugin;
impl Plugin for HudPlugin {
    fn build(&self, app: &mut App) {
        app.add_systems(Startup, setup);
        app.add_systems(Update, (
            update_hud,
            handle_input,
            handle_target_event,
        ));
        app.add_systems(PostUpdate, (
            update_overlay_visibility,
            update_ar_overlays
                .after(actor::position_to_transform)
                .in_set(sync::SyncSet::PositionToTransform),
            update_poi_overlays
                .after(actor::position_to_transform)
                .in_set(sync::SyncSet::PositionToTransform),
            update_target_selectagon
                .after(PhysicsSet::Sync)
                .after(camera::apply_input_to_player)
                .before(TransformSystem::TransformPropagate),
        ));
        app.insert_resource(AugmentedRealityState {
            overlays_visible: false,
        });
        app.insert_resource(Log {
            logs: VecDeque::with_capacity(LOG_MAX),
            needs_rerendering: true,
        });
        app.insert_resource(FPSUpdateTimer(
                Timer::from_seconds(HUD_REFRESH_TIME, TimerMode::Repeating)));
        app.add_event::<TargetEvent>();
        app.add_event::<UpdateOverlayVisibility>();
    }
}

#[derive(Event)] pub struct TargetEvent(pub Option<Entity>);
#[derive(Event)] pub struct UpdateOverlayVisibility;
#[derive(Component)] struct NodeHud;
#[derive(Component)] struct NodeConsole;
#[derive(Component)] struct NodeChoiceText;
#[derive(Component)] struct NodeCurrentChatLine;
#[derive(Component)] struct Reticule;
#[derive(Component)] pub struct ToggleableHudElement;
#[derive(Component)] pub struct ToggleableHudMapElement;
#[derive(Component)] struct Selectagon;
#[derive(Component)] pub struct IsTargeted;
#[derive(Component)] pub struct PointOfInterestMarker(pub Entity);

#[derive(Resource)]
pub struct AugmentedRealityState {
    pub overlays_visible: bool,
}

#[derive(Component)] pub struct AugmentedRealityOverlayBroadcaster;
#[derive(Component)]
pub struct AugmentedRealityOverlay {
    pub owner: Entity,
}

#[derive(Resource)]
struct FPSUpdateTimer(Timer);

pub enum LogLevel {
    Always,
    Warning,
    //Error,
    Info,
    //Debug,
    Chat,
    //Ping,
}

struct Message {
    text: String,
    sender: String,
    level: LogLevel,
    time: f64,
}
impl Message {
    pub fn get_freshness(&self) -> f64 {
        if let Ok(epoch) = SystemTime::now().duration_since(SystemTime::UNIX_EPOCH) {
            return (1.0 - (epoch.as_secs_f64() - self.time) / LOG_MAX_TIME_S).clamp(0.0, 1.0);
        }
        return 1.0;
    }
    pub fn format(&self) -> String {
        if self.sender.is_empty() {
            return self.text.clone() + "\n";
        }
        else {
            return format!("{}: {}\n", self.sender, self.text);
        }
    }
}

#[derive(Component)]
pub struct IsClickable {
    pub name: Option<String>,
    pub pronoun: Option<String>,
    pub distance: Option<f64>,
}
impl Default for IsClickable { fn default() -> Self { Self {
    name: None,
    pronoun: None,
    distance: None,
}}}

#[derive(Resource)]
pub struct Log {
    logs: VecDeque<Message>,
    needs_rerendering: bool,
}

impl Log {
    pub fn info(&mut self, message: String) {
        self.add(message, "System".to_string(), LogLevel::Info);
    }

    pub fn chat(&mut self, message: String, sender: String) {
        self.add(message, sender, LogLevel::Chat);
    }

    pub fn warning(&mut self, message: String) {
        self.add(message, "WARNING".to_string(), LogLevel::Warning);
    }

    pub fn add(&mut self, text: String, sender: String, level: LogLevel) {
        if self.logs.len() == LOG_MAX {
            self.logs.pop_front();
        }
        if let Ok(epoch) = SystemTime::now().duration_since(SystemTime::UNIX_EPOCH) {
            self.logs.push_back(Message {
                text,
                sender,
                level,
                time: epoch.as_secs_f64(),
            });
            self.needs_rerendering = true;
        }
    }

    #[allow(dead_code)]
    pub fn remove_old(&mut self) {
        if let Some(message) = self.logs.front() {
            if let Ok(epoch) = SystemTime::now().duration_since(SystemTime::UNIX_EPOCH) {
                if epoch.as_secs_f64() - message.time > LOG_MAX_TIME_S {
                    self.logs.pop_front();
                }
            }
        }
    }

    pub fn clear(&mut self) {
        self.logs.clear();
    }
}

fn setup(
    mut commands: Commands,
    settings: Res<var::Settings>,
    asset_server: Res<AssetServer>,
    mut ew_updateoverlays: EventWriter<UpdateOverlayVisibility>,
) {
    let visibility = if settings.hud_active {
        Visibility::Inherited
    } else {
        Visibility::Hidden
    };
    let font_handle = asset_server.load(FONT);
    let style_conversations = TextStyle {
        font: font_handle.clone(),
        font_size: settings.font_size_conversations,
        color: settings.hud_color_subtitles,
        ..default()
    };
    let style_console = TextStyle {
        font: font_handle.clone(),
        font_size: settings.font_size_console,
        color: settings.hud_color_console,
        ..default()
    };
    let style_choices = TextStyle {
        font: font_handle.clone(),
        font_size: settings.font_size_choices,
        color: settings.hud_color_choices,
        ..default()
    };
    let style = TextStyle {
        font: font_handle,
        font_size: settings.font_size_hud,
        color: settings.hud_color,
        ..default()
    };

    // Add Statistics HUD
    let version = &settings.version;
    let mut bundle_fps = TextBundle::from_sections([
        TextSection::new("", style.clone()),
        TextSection::new(format!(" OutFlyOS v{version} ⚡ "), style.clone()),
        TextSection::new("", style.clone()),
        TextSection::new(" ☣ ", style.clone()),
        TextSection::new("", style.clone()),
        TextSection::new("", style.clone()),
        TextSection::new("\n氧 OXYGEN ", style.clone()),
        TextSection::new("", style.clone()),
        TextSection::new("\nProximity 警告 ", style.clone()),
        TextSection::new("", style.clone()),
        TextSection::new("\nSuit Integrity ", style.clone()),
        TextSection::new("", style.clone()),
        TextSection::new("\nVitals ", style.clone()),
        TextSection::new("", style.clone()),
        TextSection::new("", style.clone()), // Speed
        TextSection::new("", style.clone()), // Target
    ]).with_style(Style {
        position_type: PositionType::Absolute,
        top: Val::VMin(2.0),
        left: Val::VMin(3.0),
        ..default()
    }).with_text_justify(JustifyText::Left);
    bundle_fps.visibility = visibility;
    commands.spawn((
        NodeHud,
        ToggleableHudElement,
        bundle_fps,
    ));

    // Add Console
    // This one is intentionally NOT a ToggleableHudElement. Instead, console entries
    // are filtered based on whether the hud is active or not.  LogLevel::Always is
    // even shown when hud is inactive.
    let bundle_chatbox = TextBundle::from_sections((0..LOG_MAX_ROWS).map(|_|
            TextSection::new("", style_console.clone()))
    ).with_style(Style {
        position_type: PositionType::Absolute,
        top: Val::VMin(0.0),
        right: Val::VMin(0.0),
        ..default()
    }).with_text_justify(JustifyText::Right);
    commands.spawn((
        NodeBundle {
            style: Style {
                width: Val::Percent(50.0),
                align_items: AlignItems::Start,
                position_type: PositionType::Absolute,
                top: Val::VMin(2.0),
                right: Val::VMin(3.0),
                ..default()
            },
            ..default()
        },
    )).with_children(|parent| {
         parent.spawn((
             bundle_chatbox,
             NodeConsole,
         ));
    });

    // Add Reticule
    commands.spawn((
        Reticule,
        ToggleableHudElement,
        NodeBundle {
            style: Style {
                width: Val::Px(2.0),
                height: Val::Px(2.0),
                position_type: PositionType::Absolute,
                top: Val::Vh(50.0),
                left: Val::Vw(50.0),
                ..default()
            },
            visibility,
            background_color: Color::rgb(0.4, 0.4, 0.6).into(),
            ..default()
        },
    ));

    // Chat "subtitles" and choices
    commands.spawn(NodeBundle {
        style: Style {
            width: Val::Vw(100.0),
            align_items: AlignItems::Center,
            flex_direction: FlexDirection::Column,
            position_type: PositionType::Absolute,
            bottom: Val::Vh(2.0),
            left: Val::Px(0.0),
            ..default()
        },
        ..default()
    }).with_children(|builder| {
        builder.spawn((
            TextBundle {
                text: Text {
                    sections: vec![
                        TextSection::new("", style_conversations),
                    ],
                    justify: JustifyText::Center,
                    ..default()
                },
                style: Style {
                    max_width: Val::Percent(50.0),
                    margin: UiRect {
                        bottom: Val::Vh(1.0),
                        ..default()
                    },
                    ..default()
                },
                ..default()
            },
            NodeCurrentChatLine,
        ));
        let choice_sections = (0..MAX_CHOICES).map(|_|
            TextSection::new("", style_choices.clone()));
        builder.spawn((
            TextBundle {
                text: Text {
                    sections: choice_sections.collect(),
                    ..default()
                },
                ..default()
            },
            NodeChoiceText,
        ));
    });

    // Selectagon
    let mut entitycmd = commands.spawn((
        Selectagon,
        SpatialBundle {
            visibility: Visibility::Hidden,
            ..default()
        },
    ));
    skeleton::load("selectagon", &mut entitycmd, &*asset_server);

    ew_updateoverlays.send(UpdateOverlayVisibility);
}

fn update_hud(
    diagnostics: Res<DiagnosticsStore>,
    time: Res<Time>,
    mut log: ResMut<Log>,
    player: Query<(&actor::HitPoints, &actor::Suit, &actor::ExperiencesGForce), With<actor::Player>>,
    q_camera: Query<(&Position, &LinearVelocity), With<actor::PlayerCamera>>,
    mut timer: ResMut<FPSUpdateTimer>,
    q_choices: Query<&chat::Choice>,
    q_chat: Query<&chat::Chat>,
    mut q_node_hud: Query<&mut Text, With<NodeHud>>,
    mut q_node_console: Query<&mut Text, (With<NodeConsole>, Without<NodeHud>, Without<NodeChoiceText>)>,
    mut q_node_choice: Query<&mut Text, (With<NodeChoiceText>, Without<NodeHud>, Without<NodeConsole>)>,
    mut q_node_currentline: Query<&mut Text, (With<NodeCurrentChatLine>, Without<NodeHud>, Without<NodeConsole>, Without<NodeChoiceText>)>,
    query_all_actors: Query<&actor::Actor>,
    settings: Res<var::Settings>,
    q_target: Query<(&IsClickable, Option<&Position>, Option<&LinearVelocity>), With<IsTargeted>>,
) {
    // TODO only when hud is actually on
    if timer.0.tick(time.delta()).just_finished() || log.needs_rerendering {
        let q_camera_result = q_camera.get_single();
        let player = player.get_single();
        let mut freshest_line: f64 = 0.0;
        if player.is_ok() && q_camera_result.is_ok() {
            let (hp, suit, gforce) = player.unwrap();
            let (pos, cam_v) = q_camera_result.unwrap();
            for mut text in &mut q_node_hud {
                text.sections[0].value = format!("2524-03-12 03:02");
                if let Some(fps) = diagnostics.get(&FrameTimeDiagnosticsPlugin::FPS) {
                    if let Some(value) = fps.smoothed() {
                        // Update the value of the second section
                        text.sections[4].value = format!("{value:.0}");
                    }
                }
                let power = suit.power / suit.power_max * 100.0;
                text.sections[2].value = format!("{power:}%");
                let oxy_percent = suit.oxygen / suit.oxygen_max * 100.0;

                // the remaining oxygen hud info ignores leaking suits from low integrity
                if suit.oxygen > nature::OXY_H {
                    let oxy_hour = suit.oxygen / nature::OXY_H;
                    text.sections[7].value = format!("{oxy_percent:.1}% [lasts {oxy_hour:.1} hours]");
                    text.sections[7].style.color = settings.hud_color;
                } else {
                    let oxy_min = suit.oxygen / nature::OXY_M;
                    text.sections[7].value = format!("{oxy_percent:.1}% [lasts {oxy_min:.1} min]");
                    text.sections[7].style.color = settings.hud_color_alert;
                }
                //let adrenaline = lifeform.adrenaline * 990.0 + 10.0;
                //text.sections[11].value = format!("{adrenaline:.0}pg/mL");
                let vitals = 100.0 * hp.current / hp.max;
                text.sections[13].value = format!("{vitals:.0}%");
                if vitals < 50.0 {
                    text.sections[13].style.color = settings.hud_color_alert;
                } else {
                    text.sections[13].style.color = settings.hud_color;
                }
                let all_actors = query_all_actors.iter().len();
                text.sections[9].value = format!("{all_actors:.0}");
                let integrity = suit.integrity * 100.0;
                if integrity < 50.0 {
                    text.sections[11].style.color = settings.hud_color_alert;
                    text.sections[11].value = format!("{integrity:.0}% [LEAKING]");
                } else {
                    text.sections[11].style.color = settings.hud_color;
                    text.sections[11].value = format!("{integrity:.0}%");
                }
                //text.sections[17].value = format!("{speed_readable}/s / {kmh:.0}km/h / {gforce:.1}g");

                // Target display
                let dist_scalar: f64;
                let mut target_multiple = false;
                let mut target_error = false;
                if let Ok((IsClickable { distance: Some(dist), .. }, _, _)) = q_target.get_single() {
                    dist_scalar = *dist;
                }
                else {
                    let target: Option<DVec3>;
                    if let Ok((_, Some(targetpos), _)) = q_target.get_single() {
                        target = Some(targetpos.0);
                    }
                    else if q_target.is_empty() {
                        target = Some(DVec3::new(0.0, 0.0, 0.0));
                    }
                    else if q_target.iter().len() > 1 {
                        target_multiple = true;
                        target = None;
                    }
                    else {
                        target_error = true;
                        target = None;
                    }
                    if let Some(target_pos) = target {
                        let dist = pos.0 - target_pos;
                        dist_scalar = dist.length();
                    }
                    else {
                        dist_scalar = 0.0;
                    }
                }

//                let dev_speed = if settings.dev_mode {
//                    let x = pos.x;
//                    let y = pos.y;
//                    let z = pos.z;
//                    format!("\n{x:.0}\n{y:.0}\n{z:.0}")
//                } else {
//                    "".to_string()
//                };
                let dev_speed = "";
                let gforce = gforce.gforce;
                let speed = cam_v.length();
                let speed_readable = nature::readable_distance(speed);
                text.sections[14].value = format!("\n{speed_readable}/s\n{gforce:.1}g{dev_speed}");

                if target_multiple {
                    text.sections[15].value = "\n\nERROR: MULTIPLE TARGETS".to_string();
                }
                else if target_error {
                    text.sections[15].value = "\n\nERROR: FAILED TO AQUIRE TARGET".to_string();
                }
                else if let Ok((clickable, _, target_v_maybe)) = q_target.get_single() {
                    let distance = if dist_scalar.is_nan() {
                        "UNKNOWN".to_string()
                    } else if dist_scalar != 0.0 {
                        nature::readable_distance(dist_scalar)
                    } else {
                        "ERROR".to_string()
                    };
                    let speed: f64 = if let Some(target_v) = target_v_maybe {
                        (target_v.0 - cam_v.0).length()
                    } else {
                        cam_v.length()
                    };
                    let speed_readable = nature::readable_distance(speed);
                    let target_name = clickable.name.clone().unwrap_or("Unnamed".to_string());
                    let pronoun = if let Some(pronoun) = &clickable.pronoun {
                        format!("Pronoun: {pronoun}\n")
                    } else {
                        "".to_string()
                    };
                    text.sections[15].value = format!("\n\nTarget: {target_name}\n{pronoun}Distance: {distance}\nΔv {speed_readable}/s");
                }
                else {
                    text.sections[15].value = "".to_string();
                }
            }
        }

        let chat = q_node_console.get_single_mut();
        if chat.is_err() {
            error!("Couldn't find HUD UI text section");
            return;
        }
        let mut chat = chat.unwrap();

        let choicebox = q_node_choice.get_single_mut();
        if choicebox.is_err() {
            error!("Couldn't find HUD UI text section");
            return;
        }
        let mut choicebox = choicebox.unwrap();

        let node_currentline = q_node_currentline.get_single_mut();
        if node_currentline.is_err() {
            error!("Couldn't find HUD UI text section");
            return;
        }
        let mut node_currentline = node_currentline.unwrap();

        let mut row = 0;

        // Chat Log and System Log
        let logfilter = if settings.hud_active {
            |_msg: &&Message| { true }
        } else {
            |msg: &&Message| { match msg.level {
                LogLevel::Always => true,
                _ => false
            }}
        };
        let messages: Vec<&Message> = log.logs.iter()
            .filter(logfilter)
            .rev()
            .take(LOG_MAX_ROWS)
            .collect();
        //messages.reverse();
        for msg in &messages {
            chat.sections[row].value = msg.format();
            let freshness = msg.get_freshness();
            let opacity: f32 = (freshness.powf(1.5) as f32).clamp(0.0, 1.0);
            freshest_line = freshest_line.max(freshness);
            chat.sections[row].style.color = match msg.level {
                LogLevel::Warning => settings.hud_color_console_warn,
                LogLevel::Info => settings.hud_color_console_system,
                _ => settings.hud_color_console,
            };
            chat.sections[row].style.color.set_a(opacity);
            row += 1;
        }

        // Display the last chat line as "subtitles"
        if !q_chat.is_empty() {
            let messages: Vec<&Message> = log.logs.iter()
                .filter(|msg: &&Message| { match msg.level {
                    LogLevel::Chat => true,
                    _ => false
                }})
                .rev()
                .take(1)
                .collect();
            if messages.len() > 0 {
                node_currentline.sections[0].value = messages[0].format();
            } else {
                node_currentline.sections[0].value = "".to_string();
            }
        } else {
            node_currentline.sections[0].value = "".to_string();
        }

        // Blank the remaining rows
        while row < LOG_MAX_ROWS {
            chat.sections[row].value = "".to_string();
            row += 1;
        }

        // Choices
        row = 0;
        let mut choices: Vec<String> = Vec::new();
        let mut count = 0;
        for choice in &q_choices {
            if count > 9 {
                break;
            }
            let press_this = REPLY_NUMBERS[choice.key];
            let reply = &choice.text;
            //let recipient = &choice.recipient;
            // TODO: indicate recipients if there's more than one
            choices.push(format!("{press_this}  {reply}"));
            count += 1;
        }
        for choice in choices {
            if row >= MAX_CHOICES {
                break;
            }
            choicebox.sections[row].value = choice + "\n";
            row += 1;
        }

        while row < MAX_CHOICES {
            choicebox.sections[row].value = if row < 4 {
                " \n".to_string()
            } else {
                "".to_string()
            };
            row += 1;
        }

        log.needs_rerendering = false;

        //if q_choices.is_empty() && freshest_line < 0.2 {
        log.remove_old();
        //}
    }
}

fn handle_input(
    keyboard_input: Res<ButtonInput<KeyCode>>,
    mouse_input: Res<ButtonInput<MouseButton>>,
    mut settings: ResMut<var::Settings>,
    mut log: ResMut<Log>,
    mut ew_sfx: EventWriter<audio::PlaySfxEvent>,
    mut ew_togglemusic: EventWriter<audio::ToggleMusicEvent>,
    mut ew_target: EventWriter<TargetEvent>,
    mut ew_updateoverlays: EventWriter<UpdateOverlayVisibility>,
    q_objects: Query<(Entity, &Transform), (With<IsClickable>, Without<IsTargeted>, Without<actor::PlayerDrivesThis>, Without<actor::Player>)>,
    q_camera: Query<&Transform, With<Camera>>,
) {
    if keyboard_input.just_pressed(settings.key_help) {
        for line in include_str!("data/keybindings.in").trim().lines().rev() {
            log.add(line.to_string(), "".to_string(), LogLevel::Always);
        }
    }
    if keyboard_input.just_pressed(settings.key_togglehud) {
        settings.hud_active ^= true;
        ew_sfx.send(audio::PlaySfxEvent(audio::Sfx::Switch));
        ew_togglemusic.send(audio::ToggleMusicEvent());
        ew_updateoverlays.send(UpdateOverlayVisibility);
    }
    if settings.hud_active && mouse_input.just_pressed(settings.key_selectobject) {
        if let Ok(camtrans) = q_camera.get_single() {
            let objects: Vec<(Entity, &Transform)> = q_objects.iter().collect();
            if let (Some(new_target), _dist) = camera::find_closest_target::<Entity>(objects, camtrans) {
                ew_target.send(TargetEvent(Some(new_target)));
            }
            else {
                ew_target.send(TargetEvent(None));
            }
        }
    }
}

fn handle_target_event(
    mut commands: Commands,
    settings: Res<var::Settings>,
    mut er_target: EventReader<TargetEvent>,
    mut ew_sfx: EventWriter<audio::PlaySfxEvent>,
    q_target: Query<Entity, With<IsTargeted>>,
) {
    let mut play_sfx = false;

    for TargetEvent(target) in er_target.read() {
        for old_target in &q_target {
            commands.entity(old_target).remove::<IsTargeted>();
            play_sfx = true;
        }
        if let Some(entity) = target {
            commands.entity(*entity).insert(IsTargeted);
            play_sfx = true;
        }
        if play_sfx && !settings.mute_sfx {
            ew_sfx.send(audio::PlaySfxEvent(audio::Sfx::Click));
        }
        break; // Only accept a single event per frame
    }
}

fn update_target_selectagon(
    settings: Res<var::Settings>,
    mut q_selectagon: Query<(&mut Transform, &mut Visibility), (With<Selectagon>, Without<IsTargeted>, Without<Camera>)>,
    q_target: Query<&Transform, (With<IsTargeted>, Without<Camera>, Without<Selectagon>)>,
    q_camera: Query<&Transform, (With<Camera>, Without<IsTargeted>, Without<Selectagon>)>,
) {
    if !settings.hud_active || q_camera.is_empty() {
        return;
    }
    let camera_trans = q_camera.get_single().unwrap();

    if let Ok((mut selectagon_trans, mut selectagon_vis)) = q_selectagon.get_single_mut() {
        if let Ok(target_trans) = q_target.get_single() {
            match *selectagon_vis {
                Visibility::Hidden => { *selectagon_vis = Visibility::Visible; },
                _ => {}
            }
            selectagon_trans.translation = target_trans.translation;
            selectagon_trans.scale = target_trans.scale;
            selectagon_trans.look_at(camera_trans.translation, target_trans.up().into());

            // Enlarge Selectagon to a minimum angular diameter
            let (angular_diameter, _, _) = camera::calc_angular_diameter(
                &selectagon_trans, camera_trans);
            let min_angular_diameter = 2.0f32.to_radians();
            if angular_diameter < min_angular_diameter {
                selectagon_trans.scale *= min_angular_diameter / angular_diameter;
            }
        }
        else {
            match *selectagon_vis {
                Visibility::Hidden => {},
                _ => { *selectagon_vis = Visibility::Hidden; }
            }
        }
    }
}

fn update_ar_overlays (
    q_owners: Query<(Entity, &Transform, &Visibility), (With<AugmentedRealityOverlayBroadcaster>, Without<AugmentedRealityOverlay>)>,
    mut q_overlays: Query<(&mut Transform, &mut Visibility, &mut AugmentedRealityOverlay)>,
    settings: ResMut<var::Settings>,
    mut state: ResMut<AugmentedRealityState>,
) {
    let (need_activate, need_clean, need_update);
    if settings.hud_active {
        need_activate = !state.overlays_visible;
        need_clean = false;
    }
    else {
        need_activate = false;
        need_clean = state.overlays_visible;
    }
    need_update = settings.hud_active;
    state.overlays_visible = settings.hud_active;

    if need_update || need_clean || need_activate {
        for (mut trans, mut vis, ar) in &mut q_overlays {
            for (owner_id, owner_trans, owner_vis) in &q_owners {
                if owner_id == ar.owner {
                    *trans = *owner_trans;
                    if need_clean {
                        *vis = Visibility::Hidden;
                    }
                    else {
                        *vis = *owner_vis;
                    }
                    break;
                }
            }
        }
    }
}

fn update_poi_overlays (
    mut q_marker: Query<(&mut Transform, &PointOfInterestMarker)>,
    q_parent: Query<&Transform, Without<PointOfInterestMarker>>,
    q_camera: Query<&Transform, (With<Camera>, Without<PointOfInterestMarker>)>,
    settings: ResMut<var::Settings>,
) {
    if !settings.hud_active || !settings.map_active || q_camera.is_empty() {
        return;
    }
    let camera_trans = q_camera.get_single().unwrap();
    for (mut trans, marker) in &mut q_marker {
        if let Ok(parent_trans) = q_parent.get(marker.0) {
            // Enlarge POI marker to a minimum angular diameter
            trans.translation = parent_trans.translation;
            trans.scale = Vec3::splat(1.0);
            let (angular_diameter, _, _) = camera::calc_angular_diameter(
                &trans, camera_trans);
            let min_angular_diameter = 3.0f32.to_radians();
            if angular_diameter < min_angular_diameter {
                trans.scale *= min_angular_diameter / angular_diameter;
            }
            trans.look_at(camera_trans.translation, camera_trans.up().into());
        }
    }
}

fn update_overlay_visibility(
    mut q_marker: Query<&mut Visibility, With<PointOfInterestMarker>>,
    mut q_hudelement: Query<&mut Visibility, (With<ToggleableHudElement>, Without<PointOfInterestMarker>)>,
    mut q_selectagon: Query<&mut Visibility, (With<Selectagon>, Without<ToggleableHudElement>, Without<PointOfInterestMarker>)>,
    q_target: Query<&IsTargeted, (Without<Camera>, Without<Selectagon>, Without<PointOfInterestMarker>, Without<ToggleableHudElement>)>,
    mut ambient_light: ResMut<AmbientLight>,
    er_target: EventReader<UpdateOverlayVisibility>,
    settings: Res<var::Settings>,
) {
    if er_target.is_empty() {
        return;
    }
    let check = {|check: bool|
        if check { Visibility::Inherited } else { Visibility::Hidden }
    };
    let show_poi = check(settings.hud_active && settings.map_active);
    let show_hud = check(settings.hud_active);
    let show_selectagon = check(settings.hud_active && !q_target.is_empty());
    for mut vis in &mut q_marker {
        *vis = show_poi;
    }
    for mut vis in &mut q_hudelement {
        *vis = show_hud;
    }
    for mut vis in &mut q_selectagon {
        *vis = show_selectagon;
    }

    ambient_light.brightness = if settings.hud_active {
        AMBIENT_LIGHT_AR
    } else {
        AMBIENT_LIGHT
    };
}