From 283e5fde693df5ddf93f70bcb01223160bccbe19 Mon Sep 17 00:00:00 2001
From: Felix Roos <roos@entrecode.de>
Date: Sun, 24 Apr 2022 01:40:26 +0200
Subject: [PATCH] fix drawLine polyrhythm

---
 packages/core/drawLine.mjs           | 10 ++++------
 packages/core/test/drawLine.test.mjs |  6 +++++-
 2 files changed, 9 insertions(+), 7 deletions(-)

diff --git a/packages/core/drawLine.mjs b/packages/core/drawLine.mjs
index 2fcdb07d..2d88367f 100644
--- a/packages/core/drawLine.mjs
+++ b/packages/core/drawLine.mjs
@@ -5,17 +5,15 @@ function drawLine(pat, chars = 60) {
   let pos = Fraction(0);
   let lines = [''];
   let emptyLine = ''; // this will be the "reference" empty line, which will be copied into extra lines
-  const slots = [];
   while (lines[0].length < chars) {
     const haps = pat.queryArc(cycle, cycle + 1);
     const durations = haps.filter((hap) => hap.hasOnset()).map((hap) => hap.duration);
-    const totalSlots = gcd(...durations).inverse(); // number of character slots for the current cycle
-    slots.push(totalSlots); // remember slots for possible empty lines needed in a later cycle
-    const minDuration = durations.reduce((a, b) => a.min(b), durations[0]); // min duration = step length
+    const charFraction = gcd(...durations);
+    const totalSlots = charFraction.inverse(); // number of character slots for the current cycle
     lines = lines.map((line) => line + '|'); // add pipe character before each cycle
     emptyLine += '|';
     for (let i = 0; i < totalSlots; i++) {
-      const [begin, end] = [pos, pos.add(minDuration)];
+      const [begin, end] = [pos, pos.add(charFraction)];
       const matches = haps.filter((hap) => hap.whole.begin.lte(begin) && hap.whole.end.gte(end));
       const missingLines = matches.length - lines.length;
       if (missingLines > 0) {
@@ -31,7 +29,7 @@ function drawLine(pat, chars = 60) {
         return line + '.';
       });
       emptyLine += '.';
-      pos = pos.add(minDuration);
+      pos = pos.add(charFraction);
     }
     cycle++;
   }
diff --git a/packages/core/test/drawLine.test.mjs b/packages/core/test/drawLine.test.mjs
index 4300b119..587c45fb 100644
--- a/packages/core/test/drawLine.test.mjs
+++ b/packages/core/test/drawLine.test.mjs
@@ -1,4 +1,4 @@
-import { fastcat, stack, slowcat, silence } from '../pattern.mjs';
+import { fastcat, stack, slowcat, silence, pure } from '../pattern.mjs';
 import { strict as assert } from 'assert';
 import drawLine from '../drawLine.mjs';
 
@@ -16,6 +16,10 @@ describe('drawLine', () => {
   it('supports unequal silence', () => {
     assert.equal(drawLine(fastcat(0, silence, [1, 2]), 10), '|0-..12|0-..12');
   });
+  it('supports polyrhythms', () => {
+    '0*2 1*3';
+    assert.equal(drawLine(fastcat(pure(0).fast(2), pure(1).fast(3)), 10), '|0--0--1-1-1-');
+  });
   it('supports multiple lines', () => {
     assert.equal(
       drawLine(fastcat(0, stack(1, 2)), 10),