Merge pull request #84 from gwilymk/modify-running-sound

Modify running sound

agb/examples/mixer_basic.rs

@@ -5,6 +5,8 @@ extern crate agb;
 
 use agb::sound::mixer::SoundChannel;
 use agb::Gba;
+use agb::input::{ButtonController, Tri, Button};
+use agb::number::Num;
 
 // Music - "I will not let you let me down" by Josh Woodward, free download at http://joshwoodward.com
 const I_WILL_NOT_LET_YOU_LET_ME_DOWN: &[u8] = include_bytes!("i-will-not-let-you-let-me-down.raw");
@@ -12,15 +14,42 @@ const I_WILL_NOT_LET_YOU_LET_ME_DOWN: &[u8] = include_bytes!("i-will-not-let-you
 #[no_mangle]
 pub fn main() -> ! {
     let mut gba = Gba::new();
+    let mut input = ButtonController::new();
     let vblank_provider = gba.display.vblank.get();
 
     let mut mixer = gba.mixer.mixer();
     mixer.enable();
 
     let channel = SoundChannel::new(I_WILL_NOT_LET_YOU_LET_ME_DOWN);
-    mixer.play_sound(channel);
+    let channel_id = mixer.play_sound(channel).unwrap();
 
     loop {
+        input.update();
+
+        {
+            if let Some(channel) = mixer.get_channel(&channel_id) {
+                let half: Num<i16, 4> = Num::new(1) / 2;
+                let half_usize: Num<usize, 8> = Num::new(1) / 2;
+                match input.x_tri() {
+                    Tri::Negative => channel.panning(-half),
+                    Tri::Zero => channel.panning(0.into()),
+                    Tri::Positive => channel.panning(half),
+                };
+    
+                match input.y_tri() {
+                    Tri::Negative => channel.playback(half_usize.change_base() + 1),
+                    Tri::Zero => channel.playback(1.into()),
+                    Tri::Positive => channel.playback(half_usize),
+                };
+
+                if input.is_pressed(Button::L) {
+                    channel.volume(half);
+                } else {
+                    channel.volume(1.into());
+                }
+            }
+        }
+
         vblank_provider.wait_for_VBlank();
         mixer.vblank();
     }

agb/src/sound/mixer/mod.rs

@@ -30,6 +30,7 @@ pub struct SoundChannel {
     should_loop: bool,
 
     playback_speed: Num<usize, 8>,
+    volume: Num<i16, 4>, // between 0 and 1
 
     panning: Num<i16, 4>, // between -1 and 1
     is_done: bool,
@@ -47,20 +48,34 @@ impl SoundChannel {
             panning: 0.into(),
             is_done: false,
             priority: SoundPriority::Low,
+            volume: 1.into(),
         }
     }
 
-    pub fn should_loop(mut self) -> Self {
+    pub fn new_high_priority(data: &'static [u8]) -> Self {
+        SoundChannel {
+            data,
+            pos: 0.into(),
+            should_loop: false,
+            playback_speed: 1.into(),
+            panning: 0.into(),
+            is_done: false,
+            priority: SoundPriority::High,
+            volume: 1.into(),
+        }
+    }
+
+    pub fn should_loop(&mut self) -> &mut Self {
         self.should_loop = true;
         self
     }
 
-    pub fn playback(mut self, playback_speed: Num<usize, 8>) -> Self {
+    pub fn playback(&mut self, playback_speed: Num<usize, 8>) -> &mut Self {
         self.playback_speed = playback_speed;
         self
     }
 
-    pub fn panning(mut self, panning: Num<i16, 4>) -> Self {
+    pub fn panning(&mut self, panning: Num<i16, 4>) -> &mut Self {
         debug_assert!(panning >= Num::new(-1), "panning value must be >= -1");
         debug_assert!(panning <= Num::new(1), "panning value must be <= 1");
 
@@ -68,8 +83,15 @@ impl SoundChannel {
         self
     }
 
-    pub fn high_priority(mut self) -> Self {
-        self.priority = SoundPriority::High;
+    pub fn volume(&mut self, volume: Num<i16, 4>) -> &mut Self {
+        assert!(volume <= Num::new(1), "volume must be <= 1");
+        assert!(volume >= Num::new(0), "volume must be >= 0");
+
+        self.volume = volume;
         self
     }
+
+    pub fn stop(&mut self) {
+        self.is_done = true
+    }
 }

agb/src/sound/mixer/sw_mixer.rs

@@ -6,13 +6,17 @@ use crate::number::Num;
 pub struct Mixer {
     buffer: MixerBuffer,
     channels: [Option<SoundChannel>; 16],
+    indices: [i32; 16],
 }
 
+pub struct ChannelId(usize, i32);
+
 impl Mixer {
     pub(super) fn new() -> Self {
         Mixer {
             buffer: MixerBuffer::new(),
             channels: Default::default(),
+            indices: Default::default(),
         }
     }
 
@@ -29,8 +33,8 @@ impl Mixer {
             .write_channels(self.channels.iter_mut().flatten());
     }
 
-    pub fn play_sound(&mut self, new_channel: SoundChannel) {
-        for channel in self.channels.iter_mut() {
+    pub fn play_sound(&mut self, new_channel: SoundChannel) -> Option<ChannelId> {
+        for (i, channel) in self.channels.iter_mut().enumerate() {
             if let Some(some_channel) = channel {
                 if !some_channel.is_done {
                     continue;
@@ -38,24 +42,36 @@ impl Mixer {
             }
 
             channel.replace(new_channel);
-            return;
+            self.indices[i] += 1;
+            return Some(ChannelId(i, self.indices[i]));
         }
 
         if new_channel.priority == SoundPriority::Low {
-            return; // don't bother even playing it
+            return None; // don't bother even playing it
         }
 
-        for channel in self.channels.iter_mut() {
+        for (i, channel) in self.channels.iter_mut().enumerate() {
             if channel.as_ref().unwrap().priority == SoundPriority::High {
                 continue;
             }
 
             channel.replace(new_channel);
-            return;
+            self.indices[i] += 1;
+            return Some(ChannelId(i, self.indices[i]));
         }
 
         panic!("Cannot play more than 16 sounds at once");
     }
+
+    pub fn get_channel(&mut self, id: &ChannelId) -> Option<&'_ mut SoundChannel> {
+        if let Some(channel) = &mut self.channels[id.0] {
+            if self.indices[id.0] == id.1 && !channel.is_done {
+                return Some(channel);
+            }
+        }
+
+        None
+    }
 }
 
 // I've picked one frequency that works nicely. But there are others that work nicely
@@ -101,8 +117,8 @@ impl MixerBuffer {
                 continue;
             }
 
-            let right_amount = (channel.panning + 1) / 2;
-            let left_amount = -right_amount + 1;
+            let right_amount = ((channel.panning + 1) / 2) * channel.volume;
+            let left_amount = ((-channel.panning + 1) / 2) * channel.volume;
 
             if channel.pos + channel.playback_speed * SOUND_BUFFER_SIZE >= channel.data.len().into()
             {