feat: BlackHoleParams tunable resource

src/main.rs

@@ -5,6 +5,7 @@ use bevy::window::WindowPlugin;
 mod web;
 mod render;
 mod camera;
+mod params;
 
 fn main() {
     // On web, abort startup if WebGPU isn't available and show a message.

src/params.rs

@@ -0,0 +1,52 @@
+use bevy::prelude::*;
+
+/// All tunable black-hole parameters. Edited by the egui panel (Task 17),
+/// mirrored into BlackHoleUniforms each frame (Task 7).
+#[derive(Resource, Clone)]
+pub struct BlackHoleParams {
+    // Physics (natural units, Rs = 1)
+    pub rs: f32,
+    // Accretion disk
+    pub disk_inner: f32,
+    pub disk_outer: f32,
+    pub disk_tilt: f32,        // radians, tilt of disk plane vs. camera
+    pub disk_brightness: f32,
+    pub disk_rotation_speed: f32,
+    pub doppler_enabled: bool,
+    pub doppler_strength: f32,
+    // Renderer
+    pub steps: u32,
+    pub render_scale: f32,
+    pub star_intensity: f32,
+    pub grid_enabled: bool,
+    pub grid_density: f32,
+    // Background
+    pub skybox_intensity: f32,
+    // Planets (count matches the storage buffer; Task 14)
+    pub planet_count: u32,
+    // Kerr (Phase 2; unused in Phase 1)
+    pub spin: f32,
+}
+
+impl Default for BlackHoleParams {
+    fn default() -> Self {
+        Self {
+            rs: 1.0,
+            disk_inner: 3.0,
+            disk_outer: 15.0,
+            disk_tilt: 1.318,      // ~75.5 deg, matching the reference video
+            disk_brightness: 1.0,
+            disk_rotation_speed: 0.5,
+            doppler_enabled: true,
+            doppler_strength: 1.0,
+            steps: 300,
+            render_scale: 1.0,
+            star_intensity: 1.0,
+            grid_enabled: false,
+            grid_density: 1.0,
+            skybox_intensity: 0.0, // procedural stars only by default
+            planet_count: 0,
+            spin: 0.0,
+        }
+    }
+}

src/render/plugin.rs

@@ -11,6 +11,7 @@ impl Plugin for BlackHolePlugin {
             .add_systems(Startup, spawn_fullscreen_quad)
             .add_systems(Update, update_time)
             .init_resource::<crate::camera::OrbitCamera>()
+            .init_resource::<crate::params::BlackHoleParams>()
             .add_systems(Update, crate::camera::orbit_controller);
     }
 }