From 7e7b8e74325d63389360a6a92d6d135a46504a56 Mon Sep 17 00:00:00 2001
From: yuni <hut@hut.pm>
Date: Mon, 16 Sep 2024 01:17:43 +0200
Subject: [PATCH] particles: fade out transparency over time

---
 src/camera.rs |  3 ++-
 src/visual.rs | 50 ++++++++++++++++++++++++++++++++++++++++++++++----
 2 files changed, 48 insertions(+), 5 deletions(-)

diff --git a/src/camera.rs b/src/camera.rs
index 6cc0bb2..ff5b6bf 100644
--- a/src/camera.rs
+++ b/src/camera.rs
@@ -430,6 +430,7 @@ pub fn apply_input_to_player(
         (&Position, &LinearVelocity),
         (
             Without<hud::IsTargeted>,
+            Without<visual::IsEffect>,
             Without<actor::PlayerCamera>,
             Without<actor::Player>,
             Without<actor::PlayerDrivesThis>,
@@ -571,7 +572,7 @@ pub fn apply_input_to_player(
                 let thruster_direction = acceleration_total.normalize();
                 let thruster_v = v.0 - 10.0 * thruster_direction;
                 ew_effect.send(visual::SpawnEffectEvent {
-                    duration: 1.0,
+                    duration: 2.0,
                     class: visual::Effects::ThrusterParticle(pos.clone(), LinearVelocity::from(thruster_v)),
                 });
             }
diff --git a/src/visual.rs b/src/visual.rs
index 2eec69f..6afcd24 100644
--- a/src/visual.rs
+++ b/src/visual.rs
@@ -27,6 +27,7 @@ impl Plugin for VisualPlugin {
         app.add_systems(Update, spawn_effects);
         app.add_systems(Update, update_fadein);
         app.add_systems(Update, update_fadeout);
+        app.add_systems(Update, update_fade_material);
         app.add_systems(Update, update_grow);
         app.add_systems(Update, play_animations);
         // Blackout disabled for now
@@ -45,12 +46,19 @@ pub enum Effects {
 // Blackout disabled for now
 //#[derive(Component)] pub struct BlackOutOverlay;
 
+#[derive(Component)]
+pub struct IsEffect;
 #[derive(Component)]
 pub struct FadeInSprite;
 #[derive(Component)]
 pub struct FadeOutSprite;
 #[derive(Component)]
-pub struct FadeOut3DObject;
+pub struct FadeMaterial {
+    pub start_time: f64,
+    pub duration: f64,
+    pub value_start: f32,
+    pub value_end: f32,
+}
 #[derive(Component)]
 pub struct Grow3DObject {
     pub start_time: f64,
@@ -131,6 +139,7 @@ pub fn spawn_effects(
         match effect.class {
             Effects::FadeIn(color) => {
                 commands.spawn((
+                    IsEffect,
                     Effect {
                         class: effect.class.clone(),
                         duration: effect.duration,
@@ -146,6 +155,7 @@ pub fn spawn_effects(
             }
             Effects::FadeOut(color) => {
                 commands.spawn((
+                    IsEffect,
                     Effect {
                         class: effect.class.clone(),
                         duration: effect.duration,
@@ -162,6 +172,7 @@ pub fn spawn_effects(
             Effects::ThrusterParticle(pos, v) => {
                 let texture = asset_server.load("textures/exhaust.png");
                 commands.spawn((
+                    IsEffect,
                     RigidBody::Kinematic,
                     bevy::pbr::NotShadowCaster,
                     pos,
@@ -170,9 +181,15 @@ pub fn spawn_effects(
                         start_time: now,
                         duration: effect.duration,
                         scale_start: 1.0,
-                        scale_end: 10.0,
+                        scale_end: 20.0,
                     },
-                    world::DespawnAt(now + effect.duration * 3.0),
+                    FadeMaterial {
+                        start_time: now,
+                        duration: effect.duration,
+                        value_start: 0.1,
+                        value_end: 0.0,
+                    },
+                    world::DespawnAt(now + effect.duration),
                     world::DespawnOnPlayerDeath,
                     actor::WantsToLookAt(cmd::ID_SPECIAL_PLAYERCAM.into()),
                     PbrBundle {
@@ -180,6 +197,7 @@ pub fn spawn_effects(
                         material: materials.add(StandardMaterial {
                             base_color_texture: Some(texture),
                             perceptual_roughness: 1.0,
+                            metallic: 0.5,
                             alpha_mode: AlphaMode::Blend,
                             ..Default::default()
                         }),
@@ -223,6 +241,31 @@ pub fn update_fadeout(
     }
 }
 
+pub fn update_fade_material(
+    mut commands: Commands,
+    mut q_object: Query<(Entity, &Handle<StandardMaterial>, &FadeMaterial)>,
+    time: Res<Time>,
+    mut materials: ResMut<Assets<StandardMaterial>>,
+) {
+    let now = time.elapsed_seconds_f64();
+    for (entity, material_handle, data) in q_object.iter_mut() {
+        let end_time = data.start_time + data.duration;
+        let material = materials.get_mut(material_handle).unwrap();
+        if now > end_time {
+            material.base_color.set_alpha(data.value_end);
+            commands.entity(entity).remove::<FadeMaterial>();
+        }
+        else if now < data.start_time {
+            material.base_color.set_alpha(data.value_start);
+        }
+        else {
+            let progress = ((now - data.start_time) / data.duration) as f32;
+            let value = data.value_start + progress * (data.value_end - data.value_start);
+            material.base_color.set_alpha(value);
+        }
+    }
+}
+
 pub fn update_grow(
     mut commands: Commands,
     mut q_object: Query<(Entity, &mut Transform, &Grow3DObject)>,
@@ -242,7 +285,6 @@ pub fn update_grow(
             let progress = ((now - data.start_time) / data.duration) as f32;
             let scale = data.scale_start + progress * (data.scale_end - data.scale_start);
             trans.scale = Vec3::splat(scale);
-            dbg!(progress, scale, trans.scale);
         }
     }
 }