From 7802a295f8566b612469eed1024a85d22e4d8f27 Mon Sep 17 00:00:00 2001
From: Melody Horn <melody@boringcactus.com>
Date: Sun, 9 May 2021 17:42:24 -0600
Subject: create some musical structure

---
 src/main.rs | 58 +++++++++++++++++++++++++++++++++++++---------------------
 1 file changed, 37 insertions(+), 21 deletions(-)

diff --git a/src/main.rs b/src/main.rs
index 2104d71..581de15 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,3 +1,4 @@
+use std::cmp::min;
 use std::time::Duration;
 
 use pitch_calc::{Letter, LetterOctave};
@@ -12,28 +13,43 @@ fn main() {
     let seconds_per_beat = (1.0 / bpm) * 60.0;
 
     let mut rng = rand::thread_rng();
+
+    // fill one measure
+    let measure = {
+        let mut measure = vec![];
+        let mut sixteenth_notes_remaining = 4 * 4;
+        while sixteenth_notes_remaining > 0 {
+            let note = [2, 3]
+                .iter()
+                .flat_map(|&octave| {
+                    use Letter::*;
+                    [C, D, E, F, G, A, B]
+                        .iter()
+                        .map(move |&letter| LetterOctave(letter, octave))
+                })
+                .choose(&mut rng)
+                .expect("how is there not a note");
+            let max_length = min(4, sixteenth_notes_remaining);
+            let length = rng.gen_range(1..=max_length);
+            sixteenth_notes_remaining -= length;
+            measure.push((note, length));
+        }
+        measure
+    };
+
     loop {
-        // This is bad.
-        let note = [2, 3]
-            .iter()
-            .flat_map(|&octave| {
-                use Letter::*;
-                [C, D, E, F, G, A, B]
-                    .iter()
-                    .map(move |&letter| LetterOctave(letter, octave))
-            })
-            .choose(&mut rng)
-            .expect("how is there not a note");
-        let freq = note.hz();
-        let wave = SineWave::new(freq as u32);
-        let length = (rng.gen_range(1..4) as f32) / 4.0 * seconds_per_beat;
-        let source = wave
-            .take_duration(Duration::from_secs_f32(length))
-            .amplify(0.10);
-        sink.append(source);
+        for (note, length) in &measure {
+            let freq = note.hz();
+            let wave = SineWave::new(freq as u32);
+            let length = (*length as f32) / 4.0 * seconds_per_beat;
+            let source = wave
+                .take_duration(Duration::from_secs_f32(length))
+                .amplify(0.10);
+            sink.append(source);
 
-        // The sound plays in a separate thread. This call will block the current thread until the sink
-        // has finished playing all its queued sounds.
-        sink.sleep_until_end();
+            // The sound plays in a separate thread. This call will block the current thread until the sink
+            // has finished playing all its queued sounds.
+            sink.sleep_until_end();
+        }
     }
 }
-- 
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