From d9a88964444b83472f8974171347a2cd85151e07 Mon Sep 17 00:00:00 2001
From: Zynh Ludwig <zynh0722@gmail.com>
Date: Sun, 1 Sep 2024 14:24:22 -0700
Subject: [PATCH] move boid_mesh code

---
 src/boid_mesh.rs | 71 +++++++++++++++++++++++++++++++++++++++++++
 src/main.rs      | 78 ++++--------------------------------------------
 2 files changed, 76 insertions(+), 73 deletions(-)
 create mode 100644 src/boid_mesh.rs

diff --git a/src/boid_mesh.rs b/src/boid_mesh.rs
new file mode 100644
index 0000000..1e50871
--- /dev/null
+++ b/src/boid_mesh.rs
@@ -0,0 +1,71 @@
+use bevy::{
+    prelude::*,
+    render::{
+        mesh::{Indices, PrimitiveTopology},
+        render_asset::RenderAssetUsages,
+    },
+    sprite::Mesh2dHandle,
+};
+use std::f32::consts::FRAC_PI_2;
+
+#[derive(Resource, Default)]
+pub struct BoidMesh(pub Mesh2dHandle);
+
+pub fn build_boid_mesh(mut meshes: ResMut<Assets<Mesh>>, mut boid_mesh: ResMut<BoidMesh>) {
+    let mesh = Mesh2dHandle(meshes.add(make_boid_mesh()));
+    boid_mesh.0 = mesh;
+}
+
+pub fn make_boid_mesh() -> Mesh {
+    const TRIANGLE_HEIGHT: f32 = 10.;
+    const TRIANGLE_WIDTH: f32 = 5.;
+    const STROKE_WIDTH: f32 = 0.25;
+
+    const HALF_HEIGHT: f32 = TRIANGLE_HEIGHT / 2.0;
+    const HALF_WIDTH: f32 = TRIANGLE_WIDTH / 2.0;
+
+    let w2 = (HALF_WIDTH * HALF_WIDTH + TRIANGLE_HEIGHT * TRIANGLE_HEIGHT).sqrt();
+    let c = STROKE_WIDTH / (HALF_WIDTH / w2);
+
+    let alpha: f32 = (TRIANGLE_HEIGHT / HALF_WIDTH).atan();
+    let b: f32 = STROKE_WIDTH * (FRAC_PI_2 - (alpha / 2.)).tan();
+
+    let mut boid_mesh = Mesh::new(
+        PrimitiveTopology::TriangleList,
+        RenderAssetUsages::RENDER_WORLD,
+    );
+
+    #[rustfmt::skip]
+    let verts = vec![
+        [0.0, HALF_HEIGHT - c, 0.0],
+        [0.0, HALF_HEIGHT, 0.0],
+        [
+            HALF_WIDTH - b,
+            -HALF_HEIGHT + STROKE_WIDTH,
+            0.0,
+        ],
+        [HALF_WIDTH, -HALF_HEIGHT, 0.0],
+        [
+            -HALF_WIDTH + b,
+            -HALF_HEIGHT + STROKE_WIDTH,
+            0.0,
+        ],
+        [-HALF_WIDTH, -HALF_HEIGHT, 0.0],
+    ];
+
+    boid_mesh.insert_attribute(Mesh::ATTRIBUTE_POSITION, verts);
+
+    #[rustfmt::skip]
+    let indices = vec![
+        0, 1, 5,
+        0, 2, 1,
+        1, 2, 3,
+        0, 5, 4,
+        3, 4, 5,
+        2, 4, 3
+    ];
+
+    boid_mesh.insert_indices(Indices::U32(indices));
+
+    boid_mesh
+}
diff --git a/src/main.rs b/src/main.rs
index c35c347..53fddd2 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,26 +1,17 @@
-use bevy::{
-    color::palettes::tailwind,
-    prelude::*,
-    render::{
-        mesh::{Indices, PrimitiveTopology},
-        render_asset::RenderAssetUsages,
-    },
-    sprite::{MaterialMesh2dBundle, Mesh2dHandle},
-};
-use std::f32::consts::FRAC_PI_2;
+mod boid_mesh;
+
+use bevy::{color::palettes::tailwind, prelude::*, sprite::MaterialMesh2dBundle};
+use boid_mesh::BoidMesh;
 
 fn main() {
     App::new()
         .init_resource::<BoidMesh>()
         .add_plugins(DefaultPlugins)
-        .add_systems(Startup, (build_boid_mesh, setup).chain())
+        .add_systems(Startup, (boid_mesh::build_boid_mesh, setup).chain())
         .add_systems(Update, move_boids)
         .run();
 }
 
-#[derive(Resource, Default)]
-struct BoidMesh(Mesh2dHandle);
-
 #[derive(Component, Default)]
 struct Boid;
 
@@ -40,11 +31,6 @@ fn move_boids(mut boids: Query<(&mut Transform, &Velocity), With<Boid>>) {
     });
 }
 
-fn build_boid_mesh(mut meshes: ResMut<Assets<Mesh>>, mut boid_mesh: ResMut<BoidMesh>) {
-    let mesh = Mesh2dHandle(meshes.add(make_boid_mesh()));
-    boid_mesh.0 = mesh;
-}
-
 fn setup(
     mut commands: Commands,
     mut materials: ResMut<Assets<ColorMaterial>>,
@@ -65,57 +51,3 @@ fn setup(
         ..default()
     });
 }
-
-fn make_boid_mesh() -> Mesh {
-    const TRIANGLE_HEIGHT: f32 = 10.;
-    const TRIANGLE_WIDTH: f32 = 5.;
-    const STROKE_WIDTH: f32 = 0.25;
-
-    const HALF_HEIGHT: f32 = TRIANGLE_HEIGHT / 2.0;
-    const HALF_WIDTH: f32 = TRIANGLE_WIDTH / 2.0;
-
-    let w2 = (HALF_WIDTH * HALF_WIDTH + TRIANGLE_HEIGHT * TRIANGLE_HEIGHT).sqrt();
-    let c = STROKE_WIDTH / (HALF_WIDTH / w2);
-
-    let alpha: f32 = (TRIANGLE_HEIGHT / HALF_WIDTH).atan();
-    let b: f32 = STROKE_WIDTH * (FRAC_PI_2 - (alpha / 2.)).tan();
-
-    let mut boid_mesh = Mesh::new(
-        PrimitiveTopology::TriangleList,
-        RenderAssetUsages::RENDER_WORLD,
-    );
-
-    #[rustfmt::skip]
-    let verts = vec![
-        [0.0, HALF_HEIGHT - c, 0.0],
-        [0.0, HALF_HEIGHT, 0.0],
-        [
-            HALF_WIDTH - b,
-            -HALF_HEIGHT + STROKE_WIDTH,
-            0.0,
-        ],
-        [HALF_WIDTH, -HALF_HEIGHT, 0.0],
-        [
-            -HALF_WIDTH + b,
-            -HALF_HEIGHT + STROKE_WIDTH,
-            0.0,
-        ],
-        [-HALF_WIDTH, -HALF_HEIGHT, 0.0],
-    ];
-
-    boid_mesh.insert_attribute(Mesh::ATTRIBUTE_POSITION, verts);
-
-    #[rustfmt::skip]
-    let indices = vec![
-        0, 1, 5,
-        0, 2, 1,
-        1, 2, 3,
-        0, 5, 4,
-        3, 4, 5,
-        2, 4, 3
-    ];
-
-    boid_mesh.insert_indices(Indices::U32(indices));
-
-    boid_mesh
-}