Merge pull request #13 from tidalcycles/continuous-functions

Add continuous signals (sine, cosine, saw, etc)

strudel.mjs

@@ -148,7 +148,7 @@ class TimeSpan {
         return result
     }
 
-    get midpoint() {
+    midpoint() {
         return(this.begin.add((this.end.sub(this.begin)).div(Fraction(2))))
     }
 
@@ -671,6 +671,32 @@ function steady(value) {
     return new Pattern(span => Hap(undefined, span, value))
 }
 
+export const signal = func => {
+    const query = span => [new Hap(undefined, span, func(span.midpoint()))]
+    return new Pattern(query)
+}
+
+const _toBipolar = pat => pat.fmap(x => (x * 2) - 1)
+const _fromBipolar = pat => pat.fmap(x => (x + 1) / 2)
+
+export const sine2   = signal(t => Math.sin(Math.PI * 2 * t))
+export const sine    = _fromBipolar(sine2)
+
+export const cosine2 = sine2._early(0.25)
+export const cosine  = sine._early(0.25)
+
+export const saw     = signal(t => t % 1)
+export const saw2    = _toBipolar(saw)
+
+export const isaw    = signal(t => 1 - (t % 1))
+export const isaw2   = _toBipolar(isaw)
+
+export const tri2    = fastcat(isaw2, saw2)
+export const tri     = fastcat(isaw, saw)
+
+export const square  = signal(t => Math.floor((t*2) % 2))
+export const square2 = _toBipolar(square)
+
 function reify(thing) {
     // Tunrs something into a pattern, unless it's already a pattern
     if (thing?.constructor?.name == "Pattern") {

test/pattern.test.mjs

@@ -2,7 +2,7 @@ import Fraction from 'fraction.js'
 
 import { strict as assert } from 'assert';
 
-import {TimeSpan, Hap, Pattern, pure, stack, fastcat, slowcat, cat, sequence, polyrhythm, silence, fast, timeCat,add,sub,mul,div} from "../strudel.mjs";
+import {TimeSpan, Hap, Pattern, pure, stack, fastcat, slowcat, cat, sequence, polyrhythm, silence, fast, timeCat,add,sub,mul,div,saw,saw2,isaw,isaw2,sine,sine2,square,square2,tri,tri2} from "../strudel.mjs";
 //import { Time } from 'tone';
 import pkg from 'tone';
 const { Time } = pkg;
@@ -307,4 +307,26 @@ describe('Pattern', function() {
       )
     })
   })
+  describe('signal()', function() {
+    it('Can make saw/saw2', function() {
+      assert.deepStrictEqual(
+        saw.struct(true,true,true,true).firstCycle,
+        sequence(1/8,3/8,5/8,7/8).firstCycle
+      )
+      assert.deepStrictEqual(
+        saw2.struct(true,true,true,true).firstCycle,
+        sequence(-3/4,-1/4,1/4,3/4).firstCycle
+      )
+    })
+    it('Can make isaw/isaw2', function() {
+      assert.deepStrictEqual(
+        isaw.struct(true,true,true,true).firstCycle,
+        sequence(7/8,5/8,3/8,1/8).firstCycle
+      )
+      assert.deepStrictEqual(
+        isaw2.struct(true,true,true,true).firstCycle,
+        sequence(3/4,1/4,-1/4,-3/4).firstCycle
+      )
+    })
+  })
 })