add starry sky box with shader

assets/shaders/skybox.wgsl

@@ -0,0 +1,11 @@
+#import bevy_pbr::{
+    mesh_view_bindings::globals,
+    forward_io::VertexOutput,
+}
+
+@fragment
+fn fragment(in: VertexOutput) -> @location(0) vec4<f32> {
+    let pos: vec2<f32> = 10 * floor(3500 * in.uv);
+    let brightness: vec3<f32> = vec3(max((fract(dot(sin(pos),pos)) - 0.995) * 90.0, 0.0));
+    return vec4<f32>(0.01 * brightness, 1.0);
+}

src/shading.rs

@@ -6,10 +6,12 @@ pub struct ShadingPlugin;
 impl Plugin for ShadingPlugin {
     fn build(&self, app: &mut App) {
         app.add_plugins(MaterialPlugin::<JupitersRing>::default());
+        app.add_plugins(MaterialPlugin::<SkyBox>::default());
         app.add_plugins(MaterialPlugin::<ExtendedMaterial<StandardMaterial, AsteroidSurface, >>::default());
     }
 }
 
+// Jupiter's Ring
 #[derive(Asset, TypePath, AsBindGroup, Debug, Clone)]
 pub struct JupitersRing {
     pub alpha_mode: AlphaMode,
@@ -28,7 +30,16 @@ impl Material for JupitersRing {
     }
 }
 
+// Sky Box
+#[derive(Asset, TypePath, AsBindGroup, Debug, Clone)]
+pub struct SkyBox {}
+impl Material for SkyBox {
+    fn fragment_shader() -> ShaderRef {
+        "shaders/skybox.wgsl".into()
+    }
+}
 
+// Asteroid Surface
 #[derive(Asset, Reflect, AsBindGroup, Debug, Clone)]
 pub struct AsteroidSurface {
     #[uniform(100)]

src/world.rs

@@ -2,6 +2,7 @@ use crate::{actor, audio, hud, nature, shading, var};
 use bevy::prelude::*;
 use bevy::math::{DVec3, I64Vec3};
 use bevy::scene::{InstanceId, SceneInstance};
+use bevy::render::mesh::Indices;
 use bevy_xpbd_3d::prelude::*;
 use bevy_xpbd_3d::plugins::sync;
 use std::collections::HashMap;
@@ -102,7 +103,8 @@ pub fn setup(
     mut commands: Commands,
     mut meshes: ResMut<Assets<Mesh>>,
     mut materials: ResMut<Assets<StandardMaterial>>,
-    mut materials_custom: ResMut<Assets<shading::JupitersRing>>,
+    mut materials_jupiter: ResMut<Assets<shading::JupitersRing>>,
+    mut materials_skybox: ResMut<Assets<shading::SkyBox>>,
     asset_server: Res<AssetServer>,
 ) {
     // Load assets
@@ -179,13 +181,34 @@ pub fn setup(
     }
     info!("Generated {starcount} stars");
 
+    // Add shaded skybox
+    //let mut mesh = Mesh::from(Sphere::new(1e9).mesh().uv(50, 50));
+    let mut mesh = Mesh::from(Sphere::new(1e10).mesh().uv(5, 5));
+    //let mut mesh = Mesh::from(Cuboid::from_size(Vec3::splat(2e10)));
+    if let Some(Indices::U32(indices)) = mesh.indices_mut() {
+        // Reverse the order of each triangle to avoid backface culling
+        for slice in indices.chunks_mut(3) {
+            slice.reverse();
+        }
+    }
+    commands.spawn((
+        MaterialMeshBundle {
+            mesh: meshes.add(mesh),
+            material: materials_skybox.add(shading::SkyBox {}),
+            transform: Transform::from_translation(Vec3::new(0.0, 0.0, 0.0)),
+            ..default()
+        },
+        Position::from_xyz(0.0, 0.0, 0.0),
+        Rotation::from(Quat::IDENTITY),
+    ));
+
     // Add shaded ring
     let ring_radius = 229_000_000.0;
     let jupiter_radius = 71_492_000.0;
     commands.spawn((
         MaterialMeshBundle {
             mesh: meshes.add(Mesh::from(Cylinder::new(ring_radius, 1.0))),
-            material: materials_custom.add(shading::JupitersRing {
+            material: materials_jupiter.add(shading::JupitersRing {
                 alpha_mode: AlphaMode::Blend,
                 ring_radius: ring_radius,
                 jupiter_radius: jupiter_radius,