From 6805c6db39c1a9409b39aaf601f78db92b684c0d Mon Sep 17 00:00:00 2001
From: Alexander Foremny <aforemny@posteo.de>
Date: Tue, 19 Mar 2024 05:14:57 +0100
Subject: feat: pull ability

---
 src/shared/ability.rs | 122 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 122 insertions(+)

(limited to 'src/shared/ability.rs')

diff --git a/src/shared/ability.rs b/src/shared/ability.rs
index e8b2a26..2c581e7 100644
--- a/src/shared/ability.rs
+++ b/src/shared/ability.rs
@@ -51,6 +51,7 @@ pub enum ActivatedAbility {
 #[derive(Copy, Clone, PartialEq, Debug, Deserialize, Serialize)]
 pub enum DirectionalAbility {
     Dash,
+    Pull,
     Spear,
 }
 
@@ -62,6 +63,7 @@ impl DirectionalAbility {
     pub fn activate(self) -> DirectionalAbilityActivation {
         match self {
             DirectionalAbility::Dash => DirectionalAbilityActivation(dash_activation),
+            DirectionalAbility::Pull => DirectionalAbilityActivation(pull_activation),
             DirectionalAbility::Spear => DirectionalAbilityActivation(spear_activation),
         }
     }
@@ -159,6 +161,126 @@ pub fn dash_collision(
     }
 }
 
+fn pull_activation(commands: &mut Commands, source_player: PlayerId, direction: Vec2) {
+    commands.add(move |world: &mut World| {
+        world.run_system_once(
+            move |players: Query<(Entity, &PlayerId)>,
+                  mut set: ParamSet<(
+                Query<&mut PlayerPosition>,
+                Query<(&PlayerId, &PlayerPosition)>,
+            )>| {
+                let Some(source_entity) = ({
+                    let mut source_entity = None;
+                    for (entity, player_id) in players.iter() {
+                        if *player_id != source_player {
+                            continue;
+                        }
+                        source_entity = Some(entity);
+                        break;
+                    }
+                    source_entity
+                }) else {
+                    return;
+                };
+
+                let Some(source_position) = ({
+                    let positions = set.p0();
+                    if let Ok(position) = positions.get(source_entity) {
+                        Some(*position)
+                    } else {
+                        None
+                    }
+                }) else {
+                    return;
+                };
+
+                let Some((target_player, _, pull_end)) = ({
+                    let pull_targets = set.p1();
+                    pull_collision(
+                        source_player,
+                        source_position.0,
+                        direction,
+                        150.,
+                        &pull_targets,
+                    )
+                }) else {
+                    return;
+                };
+
+                let Some(target_entity) = ({
+                    let mut target_entity = None;
+                    for (entity, player_id) in players.iter() {
+                        if *player_id != target_player {
+                            continue;
+                        }
+                        target_entity = Some(entity);
+                        break;
+                    }
+                    target_entity
+                }) else {
+                    return;
+                };
+
+                let mut positions = set.p0();
+                if let Ok(mut position) = positions.get_mut(target_entity) {
+                    position.0 = pull_end;
+                }
+            },
+        )
+    });
+}
+
+pub fn pull_collision(
+    source_id: PlayerId,
+    pull_start: Vec2,
+    pull_direction: Vec2,
+    pull_max_distance: f32,
+    player_positions: &Query<(&PlayerId, &PlayerPosition)>,
+) -> Option<(PlayerId, Vec2, Vec2)> {
+    let mut pull_collision = pull_max_distance * pull_direction;
+    let mut pull_player_id = None;
+    let mut pull_player_position = None;
+    for (player_id, position) in player_positions.iter() {
+        if *player_id == source_id {
+            continue;
+        }
+
+        let player_position = position.0 - pull_start;
+        let player_projection = player_position.project_onto(pull_collision);
+        let player_rejection = player_position - player_projection;
+        let scalar_factor = player_projection.dot(pull_collision).signum()
+            * player_projection.length()
+            / pull_collision.length();
+
+        if scalar_factor < 0. || scalar_factor > 1.0 {
+            continue;
+        }
+
+        if player_rejection.length() < 2. * PLAYER_RADIUS {
+            pull_player_id = Some(player_id);
+            pull_player_position = Some(position.0);
+            pull_collision = player_projection;
+        }
+    }
+
+    if let Some(target_id) = pull_player_id {
+        if let Some(target_position) = pull_player_position {
+            let pull_direction = pull_start - target_position;
+            Some((
+                *target_id,
+                target_position,
+                target_position
+                    + (pull_direction.length() - 2. * PLAYER_RADIUS)
+                        * pull_direction.normalize_or_zero(),
+            ))
+        } else {
+            None
+        }
+    } else {
+        None
+    }
+}
+
 fn spear_activation(commands: &mut Commands, source_player: PlayerId, direction: Vec2) {
     commands.add(move |world: &mut World| {
         world.run_system_once(
-- 
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