Add support for fading sounds

voxygen/src/audio/fader.rs

@@ -0,0 +1,68 @@
+
+#[derive(PartialEq, Clone, Copy)]
+pub struct Fader {
+    length: f32,
+    running_time: f32,
+    volume_from: f32,
+    volume_to: f32,
+    is_running: bool
+}
+
+fn lerp(t: f32, a: f32, b: f32) -> f32 {
+    (1.0 - t) * a  + t * b
+}
+
+impl Fader {
+    pub fn fade(time: f32, volume_from: f32, volume_to: f32) -> Self {
+        Self {
+            length: time,
+            running_time: 0.0,
+            volume_from,
+            volume_to,
+            is_running: true,
+        }
+    }
+
+    pub fn fade_in(time: f32) -> Self {
+        Self {
+            length: time,
+            running_time: 0.0,
+            volume_from: 0.0,
+            volume_to: 1.0,
+            is_running: true,
+        }
+    }
+
+    pub fn fade_out(time: f32) -> Self {
+        Self {
+            length: time,
+            running_time: 0.0,
+            volume_from: 1.0,
+            volume_to: 0.0,
+            is_running: true,
+        }
+    }
+
+    pub fn update(&mut self, dt: f32) {
+        if self.is_running {
+            self.running_time = self.running_time + dt;
+            if self.running_time >= self.length {
+                self.running_time = self.length;
+                self.is_running = false;
+            }
+        }
+    }
+
+    pub fn get_volume(&self) -> f32 {
+        lerp(self.running_time / self.length, self.volume_from, self.volume_to)
+    }
+
+    // TODO: Remove
+    pub fn get_running_time(&self) -> f32 {
+        self.running_time
+    }
+
+    pub fn is_finished(&self) -> bool {
+        self.running_time >= self.length || !self.is_running
+    }
+}

voxygen/src/audio/mod.rs

@@ -1,3 +1,6 @@
+pub mod fader;
+use fader::Fader;
+
 use common::assets;
 use rodio::{Decoder, Device, Sink, SpatialSink};
 
@@ -10,10 +13,64 @@ enum AudioType {
     Music,
 }
 
+#[derive(PartialEq, Clone, Copy)]
+enum ChannelState {
+    Playing,
+    Stopping,
+    Stopped,
+}
+
 struct Channel {
     id: usize,
     sink: SpatialSink,
     audio_type: AudioType,
+    state: ChannelState,
+    fader: Fader,
+}
+
+impl Channel {
+    pub fn music(id: usize, sink: SpatialSink) -> Self {
+        Self {
+            id,
+            sink,
+            audio_type: AudioType::Music,
+            state: ChannelState::Playing,
+            fader: Fader::fade_in(0.25),
+        }
+    }
+
+    pub fn sfx(id: usize, sink: SpatialSink) -> Self {
+        Self {
+            id,
+            sink,
+            audio_type: AudioType::Sfx,
+            state: ChannelState::Playing,
+            fader: Fader::fade_in(0.0),
+        }
+    }
+
+    pub fn stop(&mut self, fader: Fader) {
+        self.state = ChannelState::Stopping;
+        self.fader = fader;
+    }
+
+    pub fn get_state(&self) -> ChannelState {
+        self.state
+    }
+
+    pub fn update(&mut self, dt: f32) {
+        match self.state {
+            ChannelState::Playing => {},
+            ChannelState::Stopping  => {
+                self.fader.update(dt);
+                self.sink.set_volume(self.fader.get_volume());
+                if self.fader.is_finished() {
+                    self.state = ChannelState::Stopped;
+                }
+            },
+            ChannelState::Stopped => {},
+        }
+    }
 }
 
 pub struct AudioFrontend {
@@ -56,10 +113,11 @@ impl AudioFrontend {
     }
 
     /// Maintain audio
-    pub fn maintain(&mut self) {
+    pub fn maintain(&mut self, dt: f32) {
         let mut stopped_channels = Vec::<usize>::new();
-        for (i, channel) in self.channels.iter().enumerate() {
-            if channel.sink.empty() {
+        for (i, channel) in self.channels.iter_mut().enumerate() {
+            channel.update(dt);
+            if channel.sink.empty() || channel.get_state() == ChannelState::Stopped {
                 stopped_channels.push(i);
             }
         }
@@ -80,20 +138,23 @@ impl AudioFrontend {
             let sink = SpatialSink::new(device, [0.0, 0.0, 0.0], LEFT_EAR, RIGHT_EAR);
 
             let file = assets::load_file(&sound, &["wav", "ogg"]).unwrap();
-            let sound = rodio::Decoder::new(file).unwrap();
+            let sound = Decoder::new(file).unwrap();
 
             sink.append(sound);
 
-            self.channels.push(Channel {
-                id,
-                sink,
-                audio_type: AudioType::Music,
-            });
+            self.channels.push(Channel::music(id, sink));
         }
 
         id
     }
 
+    pub fn stop_channel(&mut self, channel_id: usize, fader: Fader) {
+        let index = self.channels.iter().position(|c| c.id == channel_id);
+        if let Some(index) = index {
+            self.channels[index].stop(fader);
+        }
+    }
+
     pub fn get_sfx_volume(&self) -> f32 {
         self.sfx_volume
     }

voxygen/src/main.rs

@@ -58,8 +58,8 @@ impl GlobalState {
         self.window.needs_refresh_resize();
     }
 
-    pub fn maintain(&mut self) {
-        self.audio.maintain();
+    pub fn maintain(&mut self, dt: f32) {
+        self.audio.maintain(dt);
     }
 }
 

voxygen/src/menu/char_selection/mod.rs

@@ -78,7 +78,7 @@ impl PlayState for CharSelectionState {
             }
 
             // Maintain global state.
-            global_state.maintain();
+            global_state.maintain(clock.get_last_delta().as_secs_f32());
 
             // Maintain the scene.
             self.scene.maintain(

voxygen/src/menu/main/mod.rs

@@ -3,7 +3,7 @@ mod start_singleplayer;
 mod ui;
 
 use super::char_selection::CharSelectionState;
-use crate::{window::Event, Direction, GlobalState, PlayState, PlayStateResult};
+use crate::{audio::fader::Fader, window::Event, Direction, GlobalState, PlayState, PlayStateResult};
 use client_init::{ClientInit, Error as InitError};
 use common::{clock::Clock, comp};
 use log::warn;
@@ -34,7 +34,8 @@ impl PlayState for MainMenuState {
         // Used for client creation.
         let mut client_init: Option<ClientInit> = None;
 
-        global_state.audio.play_sound("voxygen.audio.soundtrack.veloren_title_tune-3".to_string());
+        let music = global_state.audio.play_sound("voxygen.audio.soundtrack.veloren_title_tune-3".to_string());
+        global_state.audio.stop_channel(music, Fader::fade_out(10.0));
 
         loop {
             // Handle window events.
@@ -78,7 +79,7 @@ impl PlayState for MainMenuState {
             }
 
             // Maintain global_state
-            global_state.maintain();
+            global_state.maintain(clock.get_last_delta().as_secs_f32());
 
             // Maintain the UI.
             for event in self.main_menu_ui.maintain(global_state) {

voxygen/src/session.rs

@@ -271,7 +271,7 @@ impl PlayState for SessionState {
             }
 
             // Maintain global state.
-            global_state.maintain();
+            global_state.maintain(clock.get_last_delta().as_secs_f32());
 
             // Extract HUD events ensuring the client borrow gets dropped.
             let hud_events = self.hud.maintain(