From c87a68b7781d32adc27787283dd23669d4cac441 Mon Sep 17 00:00:00 2001
From: yuni <hut@hut.pm>
Date: Wed, 30 Oct 2024 05:57:29 +0100
Subject: [PATCH] add first draft of aurora shader

---
 assets/shaders/aurora.wgsl | 25 +++++++++++++++++++++++++
 src/cmd.rs                 | 26 ++++++++++++++++++++++++++
 src/data/defs.txt          |  1 +
 src/load.rs                | 16 ++++++++++++++++
 4 files changed, 68 insertions(+)
 create mode 100644 assets/shaders/aurora.wgsl

diff --git a/assets/shaders/aurora.wgsl b/assets/shaders/aurora.wgsl
new file mode 100644
index 0000000..e3f4bb7
--- /dev/null
+++ b/assets/shaders/aurora.wgsl
@@ -0,0 +1,25 @@
+#import bevy_pbr::{
+    mesh_view_bindings::globals,
+    forward_io::VertexOutput,
+}
+
+const latitude_cutoff = 50.0;
+const tau = 6.283185307179586;
+
+@fragment
+fn fragment(in: VertexOutput) -> @location(0) vec4<f32> {
+    let color = vec3<f32>(2.0, 6.0, 20.0);
+    var alpha = 0.0;
+
+    let lat = 180.0 * abs(in.uv[1] - 0.5);
+    let phase = in.uv[0] * 2.0 * 3.14159;
+    if (lat > latitude_cutoff) {
+        let y = (lat - latitude_cutoff) / (90.0 - latitude_cutoff);
+        //alpha = sin(phase * 5.0) + sin(5.0 * y);
+        alpha = 0.1 * clamp(-4.0 * cos(tau * sqrt(y + 0.01 * sin(phase * 20.0) + 0.1 * sin(phase))) - 3.0, 0.0, 1.0);
+        alpha += 0.3 * clamp(-1000.0 * cos(tau * sqrt(y + 0.01 * sin(phase * 30.0) + 0.1 * sin(phase + 0.3))) - 992.0, 0.0, 1.0);
+        alpha += 0.2 * clamp(-1000.0 * cos(tau * sqrt(-0.13 + y + 0.01 * sin(phase * 20.0) + 0.2 * sin(phase + 0.4))) - 992.0, 0.0, 1.0);
+    }
+
+    return vec4<f32>(color, clamp(alpha, 0.0, 1.0));
+}
diff --git a/src/cmd.rs b/src/cmd.rs
index e741508..06d30c1 100644
--- a/src/cmd.rs
+++ b/src/cmd.rs
@@ -106,6 +106,7 @@ struct ParserState {
     orbit_phase: Option<f64>,
     has_physics: bool,
     has_ring: bool,
+    has_aurora: bool,
     wants_maxrotation: Option<f64>,
     wants_maxvelocity: Option<f64>,
     wants_tolookat_id: Option<String>,
@@ -169,6 +170,7 @@ impl Default for ParserState {
             orbit_phase: None,
             has_physics: true,
             has_ring: false,
+            has_aurora: false,
             wants_maxrotation: None,
             wants_maxvelocity: None,
             wants_tolookat_id: None,
@@ -473,6 +475,9 @@ pub fn load_defs(mut ew_spawn: EventWriter<SpawnEvent>) {
             ["ring", "yes"] => {
                 state.has_ring = true;
             }
+            ["aurora", "yes"] => {
+                state.has_aurora = true;
+            }
             ["tidally", "locked"] => {
                 state.is_tidally_locked = true;
             }
@@ -907,6 +912,7 @@ fn spawn_entities(
     mut meshes: ResMut<Assets<Mesh>>,
     mut materials: ResMut<Assets<StandardMaterial>>,
     mut materials_jupiter: ResMut<Assets<load::JupitersRing>>,
+    mut materials_aurora: ResMut<Assets<load::JupitersAurora>>,
     mut id2pos: ResMut<game::Id2Pos>,
     mut achievement_tracker: ResMut<var::AchievementTracker>,
     mut ew_updateavatar: EventWriter<hud::UpdateAvatarEvent>,
@@ -1301,6 +1307,26 @@ fn spawn_entities(
                 NotShadowReceiver,
             ));
         }
+
+        if state.has_aurora {
+            let radius = state.model_scale * 1.01;
+            commands.spawn((
+                world::DespawnOnPlayerDeath,
+                MaterialMeshBundle {
+                    mesh: meshes.add(Sphere::new(radius).mesh().uv(128, 128)),
+                    material: materials_aurora.add(load::JupitersAurora {
+                        alpha_mode: AlphaMode::Blend,
+                    }),
+                    transform: Transform::from_translation(absolute_pos.as_vec3()),
+                    ..default()
+                },
+                Position::new(absolute_pos),
+                //Rotation::default(),
+                Rotation::from(Quat::from_rotation_x(-90f32.to_radians())),
+                NotShadowCaster,
+                NotShadowReceiver,
+            ));
+        }
     }
 }
 
diff --git a/src/data/defs.txt b/src/data/defs.txt
index c14a897..6f7ff47 100644
--- a/src/data/defs.txt
+++ b/src/data/defs.txt
@@ -89,6 +89,7 @@ actor 0 0 0
         planet yes
         sphere yes
         ring yes
+        aurora yes
         physics off
         rotationy 3.13
         rotationz 135
diff --git a/src/load.rs b/src/load.rs
index c4e665d..089ebfd 100644
--- a/src/load.rs
+++ b/src/load.rs
@@ -19,6 +19,7 @@ pub struct LoadPlugin;
 impl Plugin for LoadPlugin {
     fn build(&self, app: &mut App) {
         app.add_plugins(MaterialPlugin::<JupitersRing>::default());
+        app.add_plugins(MaterialPlugin::<JupitersAurora>::default());
         app.add_plugins(MaterialPlugin::<SkyBox>::default());
         app.add_plugins(MaterialPlugin::<
             ExtendedMaterial<StandardMaterial, AsteroidSurface>,
@@ -103,6 +104,21 @@ impl Material for JupitersRing {
     }
 }
 
+// Jupiter's Aurora
+#[derive(Asset, TypePath, AsBindGroup, Debug, Clone)]
+pub struct JupitersAurora {
+    pub alpha_mode: AlphaMode,
+}
+
+impl Material for JupitersAurora {
+    fn fragment_shader() -> ShaderRef {
+        "shaders/aurora.wgsl".into()
+    }
+    fn alpha_mode(&self) -> AlphaMode {
+        self.alpha_mode
+    }
+}
+
 // Sky Box
 #[derive(Asset, TypePath, AsBindGroup, Debug, Clone)]
 pub struct SkyBox {}