feat: smooth source movement

mbillingr · Jul 20, 2018 · d3efa64 · d3efa64
1 parent 8457a2f
commit d3efa64
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Showing 4 changed files with 48 additions and 4 deletions.
diff --git a/README.md b/README.md
@@ -28,11 +28,12 @@ let scene = AmbisonicBuilder::default().build();
 
 let source = rodio::source::SineWave::new(440);
 let mut sound = scene.play(source);
+sound.set_position([50.0, 1.0, 0.0]);
 
 // move sound from right to left
 sound.set_velocity([-10.0, 0.0, 0.0]);
 for i in 0..1000 {
-    sound.set_position([50.0 - i as f32 / 10.0, 1.0, 0.0]);
+    sound.adjust_position([50.0 - i as f32 / 10.0, 1.0, 0.0]);
     sleep(Duration::from_millis(10));
 }
 sound.set_velocity([0.0, 0.0, 0.0]);

diff --git a/src/bformat.rs b/src/bformat.rs
@@ -151,4 +151,20 @@ impl Bweights {
             z: self.z * s,
         }
     }
+
+    /// adjust weights towards target
+    pub fn approach(&mut self, target: &Bweights, max_step: f32) {
+        // if this turns out too slow we could try to replace it with simple steps along each dimension
+        let dir = [target.w - self.w, target.x - self.x, target.y - self.y, target.z - self.z];
+        let dist = (dir[0] * dir[0] + dir[1] * dir[1] + dir[2] * dir[2] + dir[3] * dir[3]).sqrt();
+        if dist <= max_step {
+            *self = *target;
+        } else {
+            let d = max_step / dist;
+            self.w += dir[0] * d;
+            self.x += dir[1] * d;
+            self.y += dir[2] * d;
+            self.z += dir[3] * d;
+        }
+    }
 }
diff --git a/src/bstream.rs b/src/bstream.rs
@@ -31,6 +31,7 @@ pub fn bstream<I: Source<Item = f32> + Send + 'static>(source: I) -> (Bstream, S
     let stream = Bstream {
         input: Box::new(source),
         bweights: Bweights::omni_source(),
+        target_weights: Bweights::omni_source(),
         speed: 1.0,
         sampling_offset: 0.0,
         previous_sample: 0.0,
@@ -46,12 +47,15 @@ pub fn bstream<I: Source<Item = f32> + Send + 'static>(source: I) -> (Bstream, S
 /// Consumes samples from the inner source and converts them to *B-format* samples.
 pub struct Bstream {
     input: Box<Source<Item = f32> + Send>,
+    bridge: Arc<BstreamBridge>,
+
     bweights: Bweights,
+    target_weights: Bweights,
+
     speed: f32,
     sampling_offset: f32,
     previous_sample: f32,
     next_sample: f32,
-    bridge: Arc<BstreamBridge>,
 }
 
 impl Bstream {}
@@ -89,6 +93,7 @@ impl Iterator for Bstream {
             for cmd in commands.drain(..) {
                 match cmd {
                     Command::SetWeights(bw) => self.bweights = bw,
+                    Command::SetTarget(bw) => self.target_weights = bw,
                     Command::SetSpeed(s) => self.speed = s,
                     Command::Stop => {
                         self.bridge.stopped.store(true, Ordering::SeqCst);
@@ -100,6 +105,10 @@ impl Iterator for Bstream {
             self.bridge.pending_commands.store(false, Ordering::SeqCst);
         }
 
+        // adjusting the weights slowly avoids audio artifacts but prevents very fast position
+        // changes
+        self.bweights.approach(&self.target_weights, 0.001);
+
         while self.sampling_offset >= 1.0 {
             match self.input.next() {
                 Some(x) => {
@@ -124,6 +133,7 @@ impl Iterator for Bstream {
 
 enum Command {
     SetWeights(Bweights),
+    SetTarget(Bweights),
     SetSpeed(f32),
     Stop,
 }
@@ -154,6 +164,21 @@ impl SoundController {
             let mut cmds = self.bridge.commands.lock().unwrap();
             cmds.push(Command::SetSpeed(rate));
             cmds.push(Command::SetWeights(weights));
+            cmds.push(Command::SetTarget(weights));
+        }
+        self.bridge.pending_commands.store(true, Ordering::SeqCst);
+    }
+    /// Adjust source position relative to listener
+    ///
+    /// The source transitions smoothly to the new position
+    pub fn adjust_position(&mut self, pos: [f32; 3]) {
+        self.position = pos;
+        let weights = Bweights::from_position(pos);
+        let rate = self.doppler_rate();
+        {
+            let mut cmds = self.bridge.commands.lock().unwrap();
+            cmds.push(Command::SetSpeed(rate));
+            cmds.push(Command::SetTarget(weights));
         }
         self.bridge.pending_commands.store(true, Ordering::SeqCst);
     }

diff --git a/src/lib.rs b/src/lib.rs
@@ -26,11 +26,12 @@
 //!
 //! let source = rodio::source::SineWave::new(440);
 //! let mut sound = scene.play(source);
+//! sound.set_position([50.0, 1.0, 0.0]);
 //!
 //! // move sound from right to left
 //! sound.set_velocity([-10.0, 0.0, 0.0]);
 //! for i in 0..1000 {
-//!     sound.set_position([50.0 - i as f32 / 10.0, 1.0, 0.0]);
+//!     sound.adjust_position([50.0 - i as f32 / 10.0, 1.0, 0.0]);
 //!     sleep(Duration::from_millis(10));
 //! }
 //! sound.set_velocity([0.0, 0.0, 0.0]);
@@ -164,11 +165,12 @@ mod tests {
 
         let source = rodio::source::SineWave::new(440);
         let mut sound = scene.play(source);
+        sound.set_position([50.0, 1.0, 0.0]);
 
         // move sound from right to left
         sound.set_velocity([-10.0, 0.0, 0.0]);
         for i in 0..1000 {
-            sound.set_position([50.0 - i as f32 / 10.0, 1.0, 0.0]);
+            sound.adjust_position([50.0 - i as f32 / 10.0, 1.0, 0.0]);
             sleep(Duration::from_millis(10));
         }
         sound.set_velocity([0.0, 0.0, 0.0]);