From ea5332e4a1a035e888709bee278fcafb182f7922 Mon Sep 17 00:00:00 2001
From: LLLL Colonq <llll@colonq>
Date: Fri, 31 Jul 2026 05:00:49 -0400
Subject: Update

---
 2026/games_submissions/rpc2dot0/src/collision.rs | 99 ++++++++++++++++++++++++
 1 file changed, 99 insertions(+)
 create mode 100644 2026/games_submissions/rpc2dot0/src/collision.rs

(limited to '2026/games_submissions/rpc2dot0/src/collision.rs')

diff --git a/2026/games_submissions/rpc2dot0/src/collision.rs b/2026/games_submissions/rpc2dot0/src/collision.rs
new file mode 100644
index 0000000..aaae9a7
--- /dev/null
+++ b/2026/games_submissions/rpc2dot0/src/collision.rs
@@ -0,0 +1,99 @@
+use crate::color::EntityColor;
+use crate::constants::{MAX_SPEED, MIN_SPEED, SPEED_COLLIDE_MULT};
+use crate::entity::Entity;
+use crate::math::BoundingCircle;
+use crate::random::RandomState;
+
+pub fn detect_collisions(entities: &[Entity], buffer: &mut Vec<(usize, usize)>) {
+    buffer.clear();
+    let len = entities.len();
+
+    for i in 0..len {
+        if !entities[i].alive {
+            continue;
+        }
+        for j in (i + 1)..len {
+            if !entities[j].alive {
+                continue;
+            }
+            if entities[i].overlaps_with(&entities[j]) {
+                buffer.push((i, j));
+            }
+        }
+    }
+}
+
+pub fn process_collisions(
+    entities: &mut Vec<Entity>,
+    rng: &mut RandomState,
+    _next_entity_id: &mut u32,
+    collision_buffer: &mut Vec<(usize, usize)>,
+    elapsed_ms: f32,
+    _events: &mut Vec<String>,
+) {
+    detect_collisions(entities, collision_buffer);
+
+    let new_entities = Vec::new();
+
+    for &(i, j) in collision_buffer.iter() {
+        if i >= entities.len() || j >= entities.len() {
+            continue;
+        }
+        if !entities[i].alive || !entities[j].alive {
+            continue;
+        }
+
+        let color_a = entities[i].color;
+        let color_b = entities[j].color;
+
+        match (color_a, color_b) {
+            (EntityColor::Green, EntityColor::Green) => {
+                if (rng.next_u32() & 1) == 0 {
+                    entities[i].color = EntityColor::Yellow;
+                    entities[j].color = EntityColor::Red;
+                    entities[j].spawn_time_ms = Some(elapsed_ms);
+                } else {
+                    entities[i].color = EntityColor::Red;
+                    entities[i].spawn_time_ms = Some(elapsed_ms);
+                    entities[j].color = EntityColor::Yellow;
+                }
+            }
+            (EntityColor::Red, EntityColor::Red) => {
+                let a = &entities[i];
+                let b = &entities[j];
+                let collision_point = (a.pos + b.pos) * 0.5;
+
+                entities[i].alive = false;
+                entities[j].alive = false;
+
+                let best_green_idx = entities
+                    .iter()
+                    .enumerate()
+                    .filter(|(_, e)| e.alive && e.color == EntityColor::Green)
+                    .min_by(|(_, e1), (_, e2)| {
+                        e1.pos
+                            .distance_squared(collision_point)
+                            .partial_cmp(&e2.pos.distance_squared(collision_point))
+                            .unwrap_or(std::cmp::Ordering::Equal)
+                    })
+                    .map(|(idx, _)| idx);
+
+                if let Some(idx) = best_green_idx {
+                    entities[idx].alive = false;
+                }
+            }
+            _ => {
+                let a_speed = (entities[i].speed * SPEED_COLLIDE_MULT).clamp(MIN_SPEED, MAX_SPEED);
+                let b_speed = (entities[j].speed * SPEED_COLLIDE_MULT).clamp(MIN_SPEED, MAX_SPEED);
+                entities[i].speed = a_speed;
+                entities[j].speed = b_speed;
+                entities[i].normalize_velocity();
+                entities[j].normalize_velocity();
+            }
+        }
+    }
+
+    if !new_entities.is_empty() {
+        entities.extend(new_entities);
+    }
+}
-- 
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