Refactor envelope to use line iterator

3 files changed, 117 insertions, 74 deletions

diff --git a/klangfarbrs/src/envelope.rs b/klangfarbrs/src/envelope.rs
index 3da7977..ce3071d 100644
--- a/klangfarbrs/src/envelope.rs
+++ b/klangfarbrs/src/envelope.rs
@@ -1,25 +1,20 @@
-use super::{Millisecond, Amplitude, SamplesPerSecond};
+use super::{Millisecond, Amplitude, SamplesPerSecond, Line};
 
 pub struct Envelope {
-    pub attack: Vec<Amplitude>,
-    pub decay: Vec<Amplitude>,
-    pub release: Vec<Amplitude>,
-    pub index: usize,
+    pub attack: Line,
+    pub decay: Line,
+    pub release: Line,
 }
 
 impl Envelope {
     pub fn new(
         attack: Millisecond, decay: Millisecond, sustain: Amplitude, release: Millisecond, sample_rate: SamplesPerSecond
     ) -> Self {
-        let attack = interpolate(0.0, 1.0, ms_to_samples(attack, sample_rate));
-        let decay = interpolate(1.0, sustain, ms_to_samples(decay, sample_rate));
-        let release = interpolate(sustain, 0.0, ms_to_samples(release, sample_rate));
+        let attack = Line::new(0.0, 1.0, attack, sample_rate);
+        let decay = Line::new(1.0, sustain, decay, sample_rate);
+        let release = Line::new(sustain, 0.0, release, sample_rate);
 
-        Self { attack, decay, release, index: 0 }
-    }
-
-    pub fn len(&self) -> usize {
-        self.attack.len() + self.decay.len() + self.release.len()
+        Self { attack, decay, release }
     }
 }
 
@@ -27,67 +22,16 @@ impl Iterator for Envelope {
     type Item = Amplitude;
 
     fn next(&mut self) -> Option<Self::Item> {
-        let idx = self.index;
-        let atk = self.attack.len();
-        let atkdcy = atk + self.decay.len();
-
-        self.index += 1;
-
-        if idx < self.len() {
-            let val = if idx < atk {
-                self.attack[idx]
-            } else if idx >= atk && idx < atkdcy  {
-                self.decay[idx - atk]
+        let mut val = self.attack.next();
+        if val.is_none() {
+            val = self.decay.next();
+            if val.is_none() {
+                self.release.next()
             } else {
-                self.release[idx - atkdcy]
-            };
-
-            Some(val)
-        } else {
-            None
-        }
-    }
-}
-
-fn interpolate(start: Amplitude, end: Amplitude, milliseconds: Millisecond) -> Vec<Amplitude> {
-    let step_size = (end - start) / milliseconds as f32;
-    let mut amps = vec!();
-    let mut current_val = start + step_size;
-
-    for i in 0..=milliseconds {
-        if i == 0 {
-            amps.push(start)
-        } else if i == milliseconds {
-            amps.push(end)
+                val
+            }
         } else {
-            amps.push(current_val);
-            current_val += step_size;
+            val
         }
     }
-
-    amps
-}
-
-fn ms_to_samples(ms: Millisecond, sample_rate: SamplesPerSecond) -> u32 {
-    let multiplier = sample_rate as u32 / 1000;
-    multiplier * ms
-}
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-
-    #[test]
-    fn it_has_expected_total_length() {
-        let expected = 3 + ms_to_samples(30, 48000.0) as usize;
-        let total = Envelope::new(10, 10, 1.0, 10, 48000.0).len();
-        assert_eq! (expected, total)
-    }
-
-    #[test]
-    fn interpolate_works() {
-        let expected = vec![0.0, 0.2, 0.4, 0.6, 0.8, 1.0];
-        let result = interpolate(0.0, 1.0, 5);
-        assert_eq!(expected, result)
-    }
 }
diff --git a/klangfarbrs/src/lib.rs b/klangfarbrs/src/lib.rs
index fc5e6f9..e64246c 100644
--- a/klangfarbrs/src/lib.rs
+++ b/klangfarbrs/src/lib.rs
@@ -13,6 +13,8 @@ use gdnative::prelude::*;
 use gdnative::core_types::TypedArray;
 
 mod phasor;
+mod line;
+use line::Line;
 
 mod osc;
 use osc::{Osc, Waveform};
@@ -46,6 +48,10 @@ pub struct MonoSynth {
     pub frequency_modulation: bool,
     pub fm_frequency: Hz,
     pub fm_depth: Amplitude,
+    pub attack: Millisecond,
+    pub decay: Millisecond,
+    pub sustain: Amplitude,
+    pub release: Millisecond,
     fm_osc: Osc,
 }
 
@@ -77,6 +83,10 @@ impl MonoSynth {
             fm_frequency: 10.0,
             fm_depth: 0.1,
             fm_osc: Osc::new(freq * 2.0, sprt),
+            attack: 10,
+            decay: 100,
+            sustain: 0.5,
+            release: 500,
         }
     }
 
@@ -157,6 +167,26 @@ impl MonoSynth {
     }
 
     #[export]
+    fn set_attack(&mut self, _owner: &Node, attack: Millisecond) {
+        self.attack = attack
+    }
+
+    #[export]
+    fn set_decay(&mut self, _owner: &Node, decay: Millisecond) {
+        self.decay = decay
+    }
+
+    #[export]
+    fn set_sustain(&mut self, _owner: &Node, sustain: Amplitude) {
+        self.sustain = sustain
+    }
+
+    #[export]
+    fn set_release(&mut self, _owner: &Node, release: Millisecond) {
+        self.release = release
+    }
+
+    #[export]
     fn envelope(
         &mut self, _owner: &Node,
         attack: Millisecond, decay: Millisecond, sustain: Amplitude, release: Millisecond
@@ -165,8 +195,9 @@ impl MonoSynth {
     }
 
     #[export]
-    fn trigger(&mut self, _owner: &Node) {
-        self.envelope.index = 0;
+    fn trigger(&mut self, _owner: &Node,    
+    ) {
+        self.envelope = Envelope::new(self.attack, self.decay, self.sustain, self.release, self.sample_rate);
     }
 
     #[export]
diff --git a/klangfarbrs/src/line.rs b/klangfarbrs/src/line.rs
new file mode 100644
index 0000000..f57b103
--- /dev/null
+++ b/klangfarbrs/src/line.rs
@@ -0,0 +1,68 @@
+use super::{Millisecond, Amplitude, SamplesPerSecond};
+
+pub struct Line {
+    pub start: Amplitude,
+    pub end: Amplitude,
+    pub duration: Millisecond,
+    pub index: u32,
+    slope: f32,
+    samples: u32
+}
+
+impl Line {
+    pub fn new(
+        start: Amplitude, end: Amplitude, duration: Millisecond, sample_rate: SamplesPerSecond
+    ) -> Self {
+        Self { start, end, duration, index: 0, slope: slope(start, end, ms_to_samples(duration, sample_rate)), samples: ms_to_samples(duration, sample_rate) }
+    }
+}
+
+impl Iterator for Line {
+    type Item = Amplitude;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        let idx = self.index;
+        let val = self.slope * idx as f32 + self.start;
+        self.index += 1;
+ 
+        if idx <= self.samples {
+            Some(val)
+        } else {
+            None
+        }
+          
+    }
+}
+
+fn slope(start: Amplitude, end: Amplitude, duration: Millisecond) -> f32 {
+  return (end - start) / duration as f32 ;
+}
+
+fn ms_to_samples(ms: Millisecond, sample_rate: SamplesPerSecond) -> u32 {
+    let multiplier = sample_rate as u32 / 1000;
+    multiplier * ms
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn it_calculates_a_slope() {
+      let expected = 0.5;
+      let slope = slope(0.0, 0.5, 1);
+      assert_eq! (expected, slope)
+    }
+
+    #[test]
+    fn it_calculates_the_next_values() {
+      let mut line = Line::new(0.0, 0.5, 1, 5000.0);
+      assert_eq!(0.0, line.next().unwrap());
+      assert_eq!(0.1, line.next().unwrap());
+      assert_eq!(0.2, line.next().unwrap());
+      assert_eq!(0.3, line.next().unwrap());
+      assert_eq!(0.4, line.next().unwrap());
+      assert_eq!(0.5, line.next().unwrap());
+      assert_eq!(None, line.next());
+    }
+}