diff --git a/README.md b/README.md
new file mode 100644
index 0000000..aef82d8
--- /dev/null
+++ b/README.md
@@ -0,0 +1,19 @@
+# Stage JSB : Simulation spatiale
+
+## Aide
+
+[Documentation de Bevy](https://docs.rs/bevy/latest/bevy/)
+
+## Commandes
+
+Vérifier la validité du code :
+
+    cargo check
+
+Compiler et lancer le programme :
+
+    cargo run
+
+Compiler et lancer le programme optimisé (plus lent à compiler, mais plus léger et rapide à exécuter) :
+
+    cargo run --release
diff --git a/src/gen.rs b/src/gen.rs
index 32243d7..ee57f63 100644
--- a/src/gen.rs
+++ b/src/gen.rs
@@ -2,28 +2,14 @@ use bevy::{prelude::*, render::render_resource::PrimitiveTopology};
 use opensimplex_noise_rs::OpenSimplexNoise;
 use rand::Rng;
 
-pub fn planet() -> Mesh {
+pub fn _planet() -> Mesh {
 	let mut rng = rand::thread_rng();
-	let simplex = OpenSimplexNoise::new(Some(rng.gen()));
+	let _simplex = OpenSimplexNoise::new(Some(rng.gen()));
 	let mut mesh = Mesh::new(PrimitiveTopology::TriangleList);
-	let perimeter: u32 = 1000;
 	mesh.insert_attribute(
 		Mesh::ATTRIBUTE_POSITION,
-		(0..perimeter)
-			.map(|i| {
-				let mut r = simplex.eval_2d(i as f64 * 0.02, 0.) as f32 * 20.0 + 100.0;
-				r += simplex.eval_2d(i as f64 * 0.05, 10.) as f32 * 10.0;
-				r += simplex.eval_2d(i as f64 * 0.2, 10.) as f32 * 4.0;
-				let a = std::f32::consts::TAU * i as f32 / perimeter as f32;
-				[r * a.cos(), r * a.sin(), 0.]
-			})
-			.chain([[0., 0., 0.]].into_iter())
-			.collect::<Vec<_>>(),
+		vec![[0.0, 0.0, 0.0], [1.0, 0.0, 0.0], [0.0, 1.0, 0.0]],
 	);
-	let mut triangles = Vec::new();
-	for i in 0..perimeter {
-		triangles.extend_from_slice(&[i, perimeter, (i + 1) % perimeter]);
-	}
-	mesh.set_indices(Some(bevy::render::mesh::Indices::U32(triangles)));
+	mesh.set_indices(Some(bevy::render::mesh::Indices::U32(vec![0, 1, 2])));
 	mesh
 }
diff --git a/src/main.rs b/src/main.rs
index 097c611..8ec9ad3 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,14 +1,11 @@
 mod gen;
-mod quadtree;
 
-use bevy::{ecs::query::BatchingStrategy, prelude::*, sprite::MaterialMesh2dBundle};
+use bevy::{prelude::*, sprite::MaterialMesh2dBundle};
 
 #[global_allocator]
 static ALLOCATOR: cap::Cap<std::alloc::System> =
 	cap::Cap::new(std::alloc::System, 1024 * 1024 * 1024);
 
-static UNIVERSE_POS: (Vec2, Vec2) = (Vec2::new(-1e6, -1e6), Vec2::new(1e6, 1e6));
-
 fn main() {
 	App::new()
 		.add_plugins((
@@ -16,16 +13,9 @@ fn main() {
 			bevy_fps_counter::FpsCounterPlugin,
 			bevy_pancam::PanCamPlugin,
 		))
-		.insert_resource(Constants { g: 6.674e-11 })
 		.add_systems(Startup, setup)
-		.configure_sets(Update, (Set::Force, Set::Apply).chain())
-		.add_systems(
-			Update,
-			(
-				weight_system.in_set(Set::Force),
-				apply_system.in_set(Set::Apply),
-			),
-		)
+		.configure_sets(Update, (Set::Demo).chain())
+		.add_systems(Update, (demo_system.in_set(Set::Demo),))
 		.run();
 }
 
@@ -38,150 +28,34 @@ fn setup(
 		.spawn(Camera2dBundle::default())
 		.insert(bevy_pancam::PanCam::default());
 
-	commands.spawn(Planet {
-		mass: Mass(1.988e18),
-		speed: Speed(Vec2::new(0.0, 0.0)),
-		mesh: MaterialMesh2dBundle {
-			mesh: meshes.add(gen::planet()).into(),
-			material: materials.add(ColorMaterial::from(Color::YELLOW)),
-			transform: Transform::from_translation(Vec3::new(0., 0., 0.)),
-			..default()
-		},
-	});
-	commands.spawn(Planet {
-		mass: Mass(5.9736e14),
-		speed: Speed(Vec2::new(0.0, 500.0)),
-		mesh: MaterialMesh2dBundle {
-			mesh: meshes.add(shape::Circle::new(10.).into()).into(),
-			material: materials.add(ColorMaterial::from(Color::BLUE)),
-			transform: Transform::from_translation(Vec3::new(400., 0., 0.)),
-			..default()
-		},
-	});
-	commands.spawn(Planet {
-		mass: Mass(5.9736e14),
-		speed: Speed(Vec2::new(0.0, -500.0)),
-		mesh: MaterialMesh2dBundle {
-			mesh: meshes.add(shape::Circle::new(10.).into()).into(),
-			material: materials.add(ColorMaterial::from(Color::BLUE)),
-			transform: Transform::from_translation(Vec3::new(-400., 0., 0.)),
-			..default()
-		},
-	});
-	for i in 0..4000u32 {
-		commands.spawn(Planet {
-			mass: Mass(1.),
-			speed: Speed(Vec2::new(0.0, -500.0)),
-			mesh: MaterialMesh2dBundle {
-				mesh: meshes.add(shape::Circle::new(5.).into()).into(),
-				material: materials.add(ColorMaterial::from(Color::RED)),
-				transform: Transform::from_translation(Vec3::new(-450. - i as f32 / 4., 0., 0.)),
+	commands
+		.spawn(Ball {
+			pos: TransformBundle::from(Transform::from_translation(Vec3::new(0., 0., 0.))),
+			visibility: InheritedVisibility::VISIBLE,
+		})
+		.with_children(|parent| {
+			parent.spawn(MaterialMesh2dBundle {
+				mesh: meshes.add(shape::Circle::new(10.).into()).into(),
+				material: materials.add(ColorMaterial::from(Color::ORANGE)),
 				..default()
-			},
+			});
 		});
-	}
 }
 
 #[derive(Clone, Debug, Eq, Hash, PartialEq, SystemSet)]
 enum Set {
-	Force,
-	Apply,
+	Demo,
 }
 
-#[derive(Component)]
-struct Speed(Vec2);
-
-#[derive(Component)]
-struct Mass(f32);
-
 #[derive(Bundle)]
-struct Planet {
-	mass: Mass,
-	speed: Speed,
-	mesh: MaterialMesh2dBundle<ColorMaterial>,
+struct Ball {
+	pos: TransformBundle,
+	visibility: InheritedVisibility,
 }
 
-#[derive(Resource)]
-struct Constants {
-	g: f32,
-}
-
-struct Body {
-	mass: f32,
-	pos: Vec2,
-}
-
-impl quadtree::Body for Body {
-	fn mass(&self) -> f32 {
-		self.mass
-	}
-	fn pos(&self) -> Vec2 {
-		self.pos
-	}
-	fn add_mass(&mut self, mass: f32) {
-		self.mass += mass;
+fn demo_system(query: Query<&Transform>, time: Res<Time>) {
+	println!("Temps écoulé : {}s", time.delta_seconds());
+	for pos in query.iter() {
+		println!("Il y a un objet aux coordonnées {:?}", pos.translation);
 	}
 }
-
-/*fn weight_system(
-	constants: Res<Constants>,
-	query1: Query<(&Transform, &Mass)>,
-	mut query2: Query<(&Transform, &mut Speed)>,
-	time: Res<Time>,
-) {
-	let gdt = constants.g * time.delta_seconds();
-	for (n1_pos, n1_mass) in query1.iter() {
-		for (n2_pos, mut n2_speed) in query2.iter_mut() {
-			let d2 = (n1_pos.translation.x - n2_pos.translation.x).powi(2)
-				+ (n1_pos.translation.y - n2_pos.translation.y).powi(2);
-			if d2 == 0.0 {
-				continue;
-			}
-			let f = n1_mass.0 * gdt / (d2 * d2.sqrt());
-			n2_speed.x += (n1_pos.translation.x - n2_pos.translation.x) * f;
-			n2_speed.y += (n1_pos.translation.y - n2_pos.translation.y) * f;
-		}
-	}
-}*/
-
-fn weight_system(
-	constants: Res<Constants>,
-	mut query: Query<(&Transform, &Mass, &mut Speed)>,
-	time: Res<Time>,
-) {
-	let mut tree = quadtree::Node::new(UNIVERSE_POS);
-	let gdt = constants.g * time.delta_seconds();
-	for (pos, mass, _speed) in query.iter() {
-		tree.add_body(Body {
-			mass: mass.0,
-			pos: pos.translation.xy(),
-		});
-	}
-	query.par_iter_mut().for_each(|(pos, _mass, mut speed)| {
-		speed.0 += gdt * tree.apply(pos.translation.xy(), 0.5);
-	});
-	// let gdt = constants.g * time.delta_seconds();
-	// let mut iter = query.iter_combinations_mut();
-	// while let Some([(n1_pos, n1_mass, mut n1_speed), (n2_pos, n2_mass, mut n2_speed)]) =
-	// 	iter.fetch_next()
-	// {
-	// 	let d2 = (n1_pos.translation.x - n2_pos.translation.x).powi(2)
-	// 		+ (n1_pos.translation.y - n2_pos.translation.y).powi(2);
-	// 	let f = gdt / (d2 * d2.sqrt());
-	// 	n1_speed.x -= (n1_pos.translation.x - n2_pos.translation.x) * f * n2_mass.0;
-	// 	n1_speed.y -= (n1_pos.translation.y - n2_pos.translation.y) * f * n2_mass.0;
-	// 	n2_speed.x += (n1_pos.translation.x - n2_pos.translation.x) * f * n1_mass.0;
-	// 	n2_speed.y += (n1_pos.translation.y - n2_pos.translation.y) * f * n1_mass.0;
-	// }
-}
-
-fn apply_system(mut query: Query<(&mut Transform, &Speed)>, time: Res<Time>) {
-	let dt = time.delta_seconds();
-	query
-		.par_iter_mut()
-		.batching_strategy(BatchingStrategy::fixed(128))
-		.for_each(|(mut pos, speed)| {
-			pos.translation.x += speed.0.x * dt;
-			pos.translation.y += speed.0.y * dt;
-		});
-}
diff --git a/src/quadtree.rs b/src/quadtree.rs
deleted file mode 100644
index c624d15..0000000
--- a/src/quadtree.rs
+++ /dev/null
@@ -1,160 +0,0 @@
-use bevy::prelude::*;
-
-pub trait Body {
-	fn mass(&self) -> f32;
-	fn pos(&self) -> Vec2;
-	fn add_mass(&mut self, mass: f32);
-}
-
-pub enum Node<L> {
-	Branch {
-		nodes: Box<[Node<L>; 4]>,
-		center: Vec2,
-		mass: f32,
-		center_of_mass: Vec2,
-		width: f32,
-	},
-	Leaf {
-		body: Option<L>,
-		pos: (Vec2, Vec2),
-	},
-}
-
-impl<L: Body> Node<L> {
-	pub fn new(pos: (Vec2, Vec2)) -> Self {
-		Node::Leaf { body: None, pos }
-		// let center = (pos.1 - pos.0) / 2.0;
-		// Node::Branch {
-		// 	nodes: [
-		// 		Box::new(Node::Leaf {
-		// 			body: None,
-		// 			pos: (pos.0, center),
-		// 		}),
-		// 		Box::new(Node::Leaf {
-		// 			body: None,
-		// 			pos: (Vec2::new(center.x, pos.0.y), Vec2::new(pos.1.x, center.y)),
-		// 		}),
-		// 		Box::new(Node::Leaf {
-		// 			body: None,
-		// 			pos: (Vec2::new(pos.0.x, center.y), Vec2::new(center.x, pos.1.y)),
-		// 		}),
-		// 		Box::new(Node::Leaf {
-		// 			body: None,
-		// 			pos: (center, pos.1),
-		// 		}),
-		// 	],
-		// 	center,
-		// 	mass: 0.0,
-		// 	center_of_mass: center,
-		// 	width: pos.1.x - pos.0.x,
-		// }
-	}
-	pub fn add_body(&mut self, new_body: L) {
-		match self {
-			Node::Branch {
-				nodes,
-				center,
-				mass,
-				center_of_mass,
-				..
-			} => {
-				let new_body_pos = new_body.pos();
-				let new_body_mass = new_body.mass();
-				*center_of_mass = (*center_of_mass * *mass + new_body_mass * new_body_pos)
-					/ (*mass + new_body_mass);
-				*mass += new_body_mass;
-				nodes[if new_body_pos.x < center.x {
-					if new_body_pos.y < center.y {
-						0
-					} else {
-						2
-					}
-				} else {
-					if new_body_pos.y < center.y {
-						1
-					} else {
-						3
-					}
-				}]
-				.add_body(new_body)
-			}
-			Node::Leaf { body, pos } => {
-				if let Some(mut body) = body.take() {
-					if body.pos().distance_squared(new_body.pos()) < 1.0 {
-						body.add_mass(new_body.mass());
-						*self = Node::Leaf {
-							body: Some(body),
-							pos: *pos,
-						};
-						return;
-					}
-					let center = (pos.0 + pos.1) / 2.0;
-					*self = Node::Branch {
-						nodes: Box::new([
-							Node::Leaf {
-								body: None,
-								pos: (pos.0, center),
-							},
-							Node::Leaf {
-								body: None,
-								pos: (Vec2::new(center.x, pos.0.y), Vec2::new(pos.1.x, center.y)),
-							},
-							Node::Leaf {
-								body: None,
-								pos: (Vec2::new(pos.0.x, center.y), Vec2::new(center.x, pos.1.y)),
-							},
-							Node::Leaf {
-								body: None,
-								pos: (center, pos.1),
-							},
-						]),
-						center,
-						mass: 0.0,
-						center_of_mass: center,
-						width: pos.1.x - pos.0.x,
-					};
-					self.add_body(body);
-					self.add_body(new_body)
-				} else {
-					*body = Some(new_body);
-				}
-			}
-		}
-	}
-
-	pub fn apply(&self, on: Vec2, theta: f32) -> Vec2 {
-		match self {
-			Node::Branch {
-				nodes,
-				mass,
-				center_of_mass,
-				width,
-				..
-			} => {
-				if on == *center_of_mass {
-					return Vec2::ZERO;
-				}
-				let dist = on.distance(*center_of_mass);
-				if width / dist < theta {
-					*mass * (*center_of_mass - on) / (dist * dist * dist)
-				} else {
-					nodes[0].apply(on, theta)
-						+ nodes[1].apply(on, theta)
-						+ nodes[2].apply(on, theta)
-						+ nodes[3].apply(on, theta)
-				}
-			}
-			Node::Leaf { body, .. } => {
-				if let Some(body) = body {
-					if on == body.pos() {
-						return Vec2::ZERO;
-					}
-					let dist = on.distance(body.pos());
-					body.mass() * (body.pos() - on) / (dist * dist * dist)
-				} else {
-					Vec2::ZERO
-				}
-			}
-		}
-	}
-}