audio: Add comments, add IsPlaying

example/audio/main.go

@@ -62,7 +62,7 @@ func square(out []float32, volume float64, freq float64, sequence float64) {
 	for i := 0; i < len(out); i++ {
 		a := float32(volume)
 		if i%length < int(float64(length)*sequence) {
-			a = 0
+			a = -a
 		}
 		out[i] = a
 	}

exp/audio/audio.go

@@ -46,9 +46,7 @@ func Queue(channel int, l []float32, r []float32) {
 	audio.Queue(channel, l, r)
 }
 
-// TODO: Add funciton to append samples to the buffer without adjusting.
+// IsPlaying returns a boolean value which indicates if the channel buffer has data to play.
-
+func IsPlaying(channel int) bool {
-// TODO: better name
+	return audio.IsPlaying(channel)
-func CurrentTime() int {
-	return audio.CurrentBytes()
 }

internal/audio/audio.go

@@ -17,8 +17,8 @@ package audio
 const bufferSize = 1024
 const SampleRate = 44100
 
-var nextInsertion = 0
+var nextInsertionPosition = 0
-var currentBytes = 0
+var currentPosition = 0
 
 type channel struct {
 	l []float32
@@ -55,8 +55,8 @@ func Play(channel int, l []float32, r []float32) bool {
 	if ch == nil {
 		return false
 	}
-	ch.l = append(ch.l, make([]float32, nextInsertion-len(ch.l))...)
+	ch.l = append(ch.l, make([]float32, nextInsertionPosition-len(ch.l))...)
-	ch.r = append(ch.r, make([]float32, nextInsertion-len(ch.r))...)
+	ch.r = append(ch.r, make([]float32, nextInsertionPosition-len(ch.r))...)
 	ch.l = append(ch.l, l...)
 	ch.r = append(ch.r, r...)
 	return true
@@ -72,26 +72,21 @@ func Queue(channel int, l []float32, r []float32) {
 	ch.r = append(ch.r, r...)
 }
 
-func CurrentBytes() int {
-	return currentBytes + nextInsertion
-}
-
 func Update() {
-	nextInsertion += SampleRate / 60
+	nextInsertionPosition += SampleRate / 60
 }
 
 func channelAt(i int) *channel {
 	if i == -1 {
-		for _, ch := range channels {
+		for i, _ := range channels {
-			if len(ch.l) <= nextInsertion {
+			if !IsPlaying(i) {
-				return ch
+				return channels[i]
 			}
 		}
 		return nil
 	}
-	ch := channels[i]
+	if !IsPlaying(i) {
-	if len(ch.l) <= nextInsertion {
+		return channels[i]
-		return ch
 	}
 	return nil
 }
@@ -122,3 +117,8 @@ func loadChannelBuffers() (l, r []float32) {
 	}
 	return inputL, inputR
 }
+
+func IsPlaying(channel int) bool {
+	ch := channels[channel]
+	return nextInsertionPosition < len(ch.l)
+}

internal/audio/audio_js.go

@@ -31,13 +31,13 @@ func initialize() {
 	node = context.Call("createScriptProcessor", bufferSize, 0, 2)
 	node.Call("addEventListener", "audioprocess", func(e js.Object) {
 		defer func() {
-			currentBytes += bufferSize
+			currentPosition += bufferSize
 		}()
 
 		l := e.Get("outputBuffer").Call("getChannelData", 0)
 		r := e.Get("outputBuffer").Call("getChannelData", 1)
 		inputL, inputR := loadChannelBuffers()
-		nextInsertion -= min(bufferSize, nextInsertion)
+		nextInsertionPosition -= min(bufferSize, nextInsertionPosition)
 		for i := 0; i < bufferSize; i++ {
 			// TODO: Use copyFromChannel?
 			if len(inputL) <= i {