From d6664b9b5a9a3aab500b547e4d7448a8bc4ad416 Mon Sep 17 00:00:00 2001
From: Kai Stevenson <kai@kaistevenson.com>
Date: Sun, 23 Aug 2026 01:07:07 -0700
Subject: allow entity damage

---
 src/sim/sim_manager/mod.rs | 61 +++++++++++++++++++++++++++++++---------------
 1 file changed, 42 insertions(+), 19 deletions(-)

(limited to 'src/sim/sim_manager')

diff --git a/src/sim/sim_manager/mod.rs b/src/sim/sim_manager/mod.rs
index 805d152..1a16cfd 100644
--- a/src/sim/sim_manager/mod.rs
+++ b/src/sim/sim_manager/mod.rs
@@ -6,7 +6,6 @@ use glam::IVec2;
 use crate::{
     Config,
     config::{PHYSICS_DELTA_TIME, PHYSICS_FPS, SIM_FPS},
-    content::materials::MaterialId,
     sim::{
         cell::cell::Cell,
         cell_manager::manager::CellManager,
@@ -130,28 +129,51 @@ impl SimManager {
         // TODO optimize
         for (entity_id, cells_written) in cells_written_by_entity {
             let entity = self.entities.get_mut(&entity_id).unwrap();
+            let entity_cells = entity.data.cells.as_mut().unwrap();
+            let mut should_update_entity = false;
+
             for (lx, ly, x, y) in cells_written {
                 // update the entity
-                // TODO we should skip cells that weren't changed?
                 // TODO optimize
                 let new_local_cell = self.cell_manager.get_cell_from_game_position(x, y).unwrap();
-                if new_local_cell.material != MaterialId::Void && !new_local_cell.entity() {
-                    panic!(
-                        "Someone swapped into this entity's cell! ({x}, {y}, {m:#?}, {f})",
-                        m = new_local_cell.material,
-                        f = new_local_cell.flags
-                    );
-                }
-                if let Some(cells) = &mut entity.data.cells {
-                    cells.set_cell_at_local_position(
-                        IVec2::new(lx as i32, ly as i32),
-                        new_local_cell,
-                    );
+                if !new_local_cell.entity_integrated() {
+                    // this means that the entity changed in some way, so we should recompute its shape
+                    // TODO wait N frames to debounce this
+                    should_update_entity = true;
                 }
+                // we do this unconditionally because it's cheaper than checking if it actually needs to be updated
+                // and because we don't have a good way to track changes to cell state
+                entity_cells
+                    .set_cell_at_local_position(IVec2::new(lx as i32, ly as i32), new_local_cell);
+
                 // update the world
+                // TODO optimize
                 self.cell_manager
                     .set_cell_from_game_position(x, y, Cell::void(), false);
             }
+
+            if should_update_entity {
+                if let Some(new_collider) = entity.compute_collider() {
+                    self.rb_manager.physics_manager.collider_set.remove(
+                        entity.data.collider_h.unwrap(),
+                        &mut self.rb_manager.physics_manager.island_manager,
+                        &mut self.rb_manager.physics_manager.rigid_body_set,
+                        true,
+                    );
+
+                    let new_handle = self
+                        .rb_manager
+                        .physics_manager
+                        .collider_set
+                        .insert_with_parent(
+                            new_collider,
+                            entity.data.rb_h.unwrap(),
+                            &mut self.rb_manager.physics_manager.rigid_body_set,
+                        );
+
+                    entity.data.collider_h = Some(new_handle);
+                }
+            }
         }
     }
 
@@ -165,15 +187,16 @@ impl SimManager {
                 particle_manager: &mut self.particle_manager,
             };
             if let Some(entity) = entity
-                && let Some(result) = entity.physics_update(&mut ctx, delta_time) {
-                    for d in result.deferred_destructions {
-                        self.destroy_entity(d);
-                    }
+                && let Some(result) = entity.physics_update(&mut ctx, delta_time)
+            {
+                for d in result.deferred_destructions {
+                    self.destroy_entity(d);
                 }
+            }
         }
 
         // before we move the rigidbodies, upsert the current terrain state
-        // TODO use the chunk sleeping, and make this range dynamic
+        // TODO make this range dynamic
         for cx in -5..5 {
             for cy in -5..5 {
                 if let Some(chunk) = self
-- 
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