From 67de2d5833bffd79a9360f1ce62402a0cc9c53a7 Mon Sep 17 00:00:00 2001
From: Gwilym Inzani <email@gwilym.dev>
Date: Sat, 5 Aug 2023 23:51:12 +0100
Subject: [PATCH] Implement fadeout

---
 tracker/agb-tracker-interop/src/lib.rs |  4 ++++
 tracker/agb-tracker/src/lib.rs         | 17 ++++++++++++-----
 tracker/agb-xm-core/src/lib.rs         |  5 +++++
 3 files changed, 21 insertions(+), 5 deletions(-)

diff --git a/tracker/agb-tracker-interop/src/lib.rs b/tracker/agb-tracker-interop/src/lib.rs
index 1132aa39..7261d683 100644
--- a/tracker/agb-tracker-interop/src/lib.rs
+++ b/tracker/agb-tracker-interop/src/lib.rs
@@ -23,6 +23,7 @@ pub struct Sample<'a> {
     pub restart_point: u32,
     pub volume: Num<i16, 8>,
     pub volume_envelope: Option<usize>,
+    pub fadeout: Num<i32, 8>,
 }
 
 #[derive(Debug)]
@@ -181,12 +182,14 @@ impl<'a> quote::ToTokens for Sample<'a> {
             restart_point,
             volume,
             volume_envelope,
+            fadeout,
         } = self;
 
         let volume_envelope = match volume_envelope {
             Some(index) => quote!(Some(#index)),
             None => quote!(None),
         };
+        let fadeout = fadeout.to_raw();
 
         let samples = ByteString(data);
         let volume = volume.to_raw();
@@ -203,6 +206,7 @@ impl<'a> quote::ToTokens for Sample<'a> {
                     restart_point: #restart_point,
                     volume: agb_tracker::__private::Num::from_raw(#volume),
                     volume_envelope: #volume_envelope,
+                    fadeout: agb_tracker::__private::Num::from_raw(#fadeout),
                 }
             }
         });
diff --git a/tracker/agb-tracker/src/lib.rs b/tracker/agb-tracker/src/lib.rs
index 86c0ef0c..533f6940 100644
--- a/tracker/agb-tracker/src/lib.rs
+++ b/tracker/agb-tracker/src/lib.rs
@@ -113,6 +113,7 @@ struct EnvelopeState {
     frame: usize,
     envelope_id: usize,
     finished: bool,
+    fadeout: Num<i32, 8>,
 }
 
 #[derive(Clone)]
@@ -179,6 +180,7 @@ impl Tracker {
                     frame: 0,
                     envelope_id,
                     finished: false,
+                    fadeout: sample.fadeout,
                 });
             }
 
@@ -212,7 +214,7 @@ impl Tracker {
 
                 if !channel.update_volume_envelope(
                     mixer,
-                    envelope_state.frame,
+                    envelope_state,
                     envelope,
                     &self.global_settings,
                 ) {
@@ -448,9 +450,9 @@ impl TrackerChannel {
 
     #[must_use]
     fn update_volume_envelope(
-        &self,
+        &mut self,
         mixer: &mut Mixer<'_>,
-        frame: usize,
+        envelope_state: &EnvelopeState,
         envelope: &agb_tracker_interop::Envelope<'_>,
         global_settings: &GlobalSettings,
     ) -> bool {
@@ -459,14 +461,19 @@ impl TrackerChannel {
             .as_ref()
             .and_then(|channel_id| mixer.channel(channel_id))
         {
-            let amount = envelope.amount[frame];
+            let amount = envelope.amount[envelope_state.frame];
+
+            if envelope_state.finished {
+                self.volume = (self.volume - envelope_state.fadeout).max(0.into());
+            }
 
             channel.volume(
                 (self.volume * amount.change_base() * global_settings.volume)
                     .try_change_base()
                     .unwrap(),
             );
-            true
+
+            self.volume != 0.into()
         } else {
             false
         }
diff --git a/tracker/agb-xm-core/src/lib.rs b/tracker/agb-xm-core/src/lib.rs
index 72f1f7da..ccc1251e 100644
--- a/tracker/agb-xm-core/src/lib.rs
+++ b/tracker/agb-xm-core/src/lib.rs
@@ -57,6 +57,7 @@ pub fn parse_module(module: &Module) -> TokenStream {
         restart_point: u32,
         volume: Num<i16, 8>,
         envelope_id: Option<usize>,
+        fadeout: Num<i32, 8>,
     }
 
     let mut samples = vec![];
@@ -109,6 +110,8 @@ pub fn parse_module(module: &Module) -> TokenStream {
                     .collect::<Vec<_>>(),
             };
 
+            let fadeout = Num::from_raw((instrument.volume_fadeout * ((1 << 8) as f32)) as i32);
+
             instruments_map.insert((instrument_index, sample_index), samples.len());
             samples.push(SampleData {
                 data: sample,
@@ -118,6 +121,7 @@ pub fn parse_module(module: &Module) -> TokenStream {
                 restart_point,
                 volume,
                 envelope_id,
+                fadeout,
             });
         }
     }
@@ -412,6 +416,7 @@ pub fn parse_module(module: &Module) -> TokenStream {
             restart_point: sample.restart_point,
             volume: sample.volume,
             volume_envelope: sample.envelope_id,
+            fadeout: sample.fadeout,
         })
         .collect();