From bdad89910dcf3a56790dba60ed1f0db679432323 Mon Sep 17 00:00:00 2001
From: Kai Stevenson <kai@kaistevenson.com>
Date: Sat, 22 Aug 2026 16:49:56 -0700
Subject: refactor entities

---
 src/sim/entity/mod.rs | 167 +++++++++++++++++++++++++++++++++++++++++---------
 1 file changed, 139 insertions(+), 28 deletions(-)

(limited to 'src/sim/entity/mod.rs')

diff --git a/src/sim/entity/mod.rs b/src/sim/entity/mod.rs
index ab10ea8..b648f1d 100644
--- a/src/sim/entity/mod.rs
+++ b/src/sim/entity/mod.rs
@@ -1,28 +1,139 @@
-// use glam::{IVec2, Vec2};
-// use rapier2d::{dynamics::RigidBodyHandle, geometry::ColliderHandle};
-
-// use crate::sim::cell::cell::Cell;
-
-// pub struct EntityCells {
-//     pub size: IVec2,
-//     pub cells: Vec<Cell>,
-// }
-// pub trait EntityBehaviour {
-//     fn update (&mut self) -> ();
-// }
-
-// pub struct Entity {
-//     pub rb_h: Option<RigidBodyHandle>,
-//     pub collider_h: Option<ColliderHandle>,
-//     pub cells: EntityCells,
-//     pub behaviour:
-// }
-
-// impl Entity {
-//     pub fn position(&self, rbsm:) -> Vec2 {
-
-//     }
-//     pub fn destroy(&mut self) -> {
-
-//     }
-// }
+use glam::{IVec2, Vec2};
+use rapier2d::{
+    dynamics::{RigidBody, RigidBodyBuilder, RigidBodyHandle},
+    geometry::{Collider, ColliderHandle},
+};
+
+use crate::{
+    config::CELLS_TO_METRES,
+    sim::{
+        cell::{cell::Cell, materials::MaterialId},
+        lib::marching_squares::Marchable,
+        rb_manager::RbManager,
+        sim_manager::SimManager,
+    },
+};
+
+pub mod entities;
+
+pub struct EntityCells {
+    pub size: IVec2,
+    pub cells: Vec<Cell>,
+}
+
+impl EntityCells {
+    #[inline]
+    pub fn get_cell_at_local_position(&self, pos: IVec2) -> Cell {
+        self.cells[pos.x as usize + pos.y as usize * self.size.x as usize]
+    }
+    #[inline]
+    pub fn set_cell_at_local_position(&mut self, pos: IVec2, cell: Cell) {
+        self.cells[pos.x as usize + pos.y as usize * self.size.x as usize] = cell;
+    }
+}
+
+impl Marchable for EntityCells {
+    fn occupied(&self, pos: IVec2) -> bool {
+        if pos.x < 0 || pos.x >= self.size.x || pos.y < 0 || pos.y >= self.size.y {
+            false
+        } else {
+            self.get_cell_at_local_position(pos).material != MaterialId::Void
+        }
+    }
+    fn size(&self) -> IVec2 {
+        self.size
+    }
+}
+
+pub trait EntityBehaviour {
+    fn update(&mut self, sim: &mut SimManager, delta_time: f32) -> ();
+    fn physics_update(&mut self, sim: &mut SimManager, delta_time: f32) -> ();
+}
+
+pub struct EntityDef {
+    pub position: Vec2,
+    pub rb: Option<RigidBody>,
+    pub collider: Option<Collider>,
+    pub cells: Option<EntityCells>,
+    pub behaviour: Option<Box<dyn EntityBehaviour>>,
+}
+
+impl EntityDef {
+    pub fn from_cells(
+        position: Vec2,
+        cells: EntityCells,
+        behaviour: Option<Box<dyn EntityBehaviour>>,
+    ) -> Self {
+        let rb = RigidBodyBuilder::dynamic()
+            .translation(position / CELLS_TO_METRES)
+            .build();
+
+        let collider = RbManager::convex_hull_collider_from_marchable(&cells, None).build();
+
+        EntityDef {
+            position,
+            rb: Some(rb),
+            collider: Some(collider),
+            cells: Some(cells),
+            behaviour,
+        }
+    }
+}
+
+pub struct Entity {
+    pub id: u32,
+    pub rb_h: Option<RigidBodyHandle>,
+    pub collider_h: Option<ColliderHandle>,
+    pub cells: Option<EntityCells>,
+    behaviour: Option<Box<dyn EntityBehaviour>>,
+}
+
+impl Entity {
+    pub fn transform(&self, sim: &SimManager) -> Option<(Vec2, (f32, f32))> {
+        self.rb_h
+            .map(|rb_h| {
+                sim.rb_manager
+                    .physics_manager
+                    .rigid_body_set
+                    .get(rb_h)
+                    .map(|rb| {
+                        (
+                            rb.translation() * CELLS_TO_METRES,
+                            (rb.rotation().cos(), rb.rotation().sin()),
+                        )
+                    })
+            })
+            .flatten()
+    }
+
+    // TODO use drop?
+    pub fn destroy(&mut self, sim: &mut SimManager) -> () {}
+
+    pub fn update(&mut self, sim: &mut SimManager, delta_time: f32) -> () {
+        if let Some(behaviour) = &mut self.behaviour {
+            behaviour.update(sim, delta_time);
+        }
+    }
+
+    pub fn physics_update(&mut self, sim: &mut SimManager, delta_time: f32) -> () {
+        if let Some(behaviour) = &mut self.behaviour {
+            behaviour.physics_update(sim, delta_time);
+        }
+    }
+
+    pub fn new(
+        id: u32,
+        rb_h: Option<RigidBodyHandle>,
+        collider_h: Option<ColliderHandle>,
+        cells: Option<EntityCells>,
+        behaviour: Option<Box<dyn EntityBehaviour>>,
+    ) -> Self {
+        Entity {
+            id,
+            rb_h,
+            collider_h,
+            cells,
+            behaviour,
+        }
+    }
+}
-- 
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