From 8f796c92fabee3456bc98de4137ec5fe7b5cc8db Mon Sep 17 00:00:00 2001
From: hut <hut@hut.pm>
Date: Tue, 14 May 2024 04:35:45 +0200
Subject: [PATCH] implement InJupitersShadow achievement

---
 src/common.rs | 34 ++++++++++++++++++++++++++++++++++
 src/game.rs   | 24 ++++++++++++++++++++++++
 2 files changed, 58 insertions(+)

diff --git a/src/common.rs b/src/common.rs
index 27d0af4..3ff15a0 100644
--- a/src/common.rs
+++ b/src/common.rs
@@ -63,3 +63,37 @@ pub fn alive(settings: Res<Settings>) -> bool {
 pub fn in_control(settings: Res<Settings>) -> bool {
     return settings.in_control();
 }
+
+pub fn in_shadow(
+    light_source_pos: DVec3,
+    light_source_r: f64,
+    shadow_caster_pos: DVec3,
+    shadow_caster_r: f64,
+    camera_pos: DVec3
+) -> bool {
+    if light_source_r < shadow_caster_r {
+        error!("common::in_shadow only works if light_source_r > shadow_caster_r");
+        return false;
+    }
+
+    let direction = (shadow_caster_pos - light_source_pos).normalize();
+    let shadow_caster_to_player = camera_pos - shadow_caster_pos;
+
+    // Calculate the distance to the shadow caster if the player was projected
+    // onto the line of the shadow, with positive numbers = in the shadow,
+    // negative numbers = in between light source and shadow caster.
+    let projection_length = shadow_caster_to_player.dot(direction);
+    if projection_length < 0.0 {
+        return false;
+    }
+
+    let projection = projection_length * direction;
+
+    // Calculate the vector to the closest point along the shadow line
+    let closest_vector = shadow_caster_to_player - projection;
+
+    let distance_between_light_and_caster = (shadow_caster_pos - light_source_pos).length();
+    let max_distance = shadow_caster_r + ((shadow_caster_r - light_source_r) / distance_between_light_and_caster) * projection_length;
+
+    return closest_vector.length() < max_distance;
+}
diff --git a/src/game.rs b/src/game.rs
index e5ef5fe..44548e5 100644
--- a/src/game.rs
+++ b/src/game.rs
@@ -27,8 +27,11 @@ impl Plugin for GamePlugin {
         app.add_systems(PreUpdate, handle_player_death);
         app.add_systems(PostUpdate, update_id2pos);
         app.add_systems(Update, handle_achievement_event.run_if(on_event::<AchievementEvent>()));
+        app.add_systems(Update, check_achievements);
         app.insert_resource(Id2Pos(HashMap::new()));
         app.insert_resource(var::AchievementTracker::default());
+        app.insert_resource(AchievementCheckTimer(
+            Timer::from_seconds(1.0, TimerMode::Repeating)));
         app.add_event::<PlayerDiesEvent>();
         app.add_event::<GameEvent>();
         app.add_event::<AchievementEvent>();
@@ -37,6 +40,7 @@ impl Plugin for GamePlugin {
 
 #[derive(Event)] pub struct PlayerDiesEvent(pub actor::DamageType);
 #[derive(Resource)] pub struct Id2Pos(pub HashMap<String, DVec3>);
+#[derive(Resource)] pub struct AchievementCheckTimer(pub Timer);
 
 #[derive(Event)]
 pub enum AchievementEvent {
@@ -396,3 +400,23 @@ fn handle_achievement_event(
         }
     }
 }
+
+fn check_achievements(
+    time: Res<Time>,
+    q_player: Query<&Position, With<actor::PlayerCamera>>,
+    id2pos: Res<Id2Pos>,
+    mut ew_achievement: EventWriter<AchievementEvent>,
+    mut timer: ResMut<AchievementCheckTimer>,
+) {
+    if !timer.0.tick(time.delta()).just_finished() { return; }
+    let pos_player = if let Ok(pos) = q_player.get_single() { pos } else { return; };
+    let pos_sun = if let Some(pos) = id2pos.0.get("sol") { pos } else { return; };
+    let pos_jupiter = if let Some(pos) = id2pos.0.get("jupiter") { pos } else { return; };
+
+    let shadowed = in_shadow(*pos_sun, nature::SOL_RADIUS,
+        *pos_jupiter, nature::JUPITER_RADIUS, **pos_player);
+
+    if shadowed {
+        ew_achievement.send(AchievementEvent::InJupitersShadow);
+    }
+}