implement Mixer

com/danitheskunk/skunkworks/TestSound.java

@@ -1,6 +1,8 @@
 package com.danitheskunk.skunkworks;
 
 import com.danitheskunk.skunkworks.audio.AudioEngine;
+import com.danitheskunk.skunkworks.audio.nodes.Mixer;
+import com.danitheskunk.skunkworks.audio.nodes.Node;
 import com.danitheskunk.skunkworks.audio.nodes.Sine;
 import org.lwjgl.openal.AL;
 import org.lwjgl.openal.ALC;
@@ -18,7 +20,14 @@ import static org.lwjgl.openal.ALC10.*;
 public class TestSound {
 	public static void main(String args[]) throws InterruptedException {
 		var engine = new AudioEngine(44100, 256, 8);
-		engine.setNode(new Sine(engine, 440));
+		var mix = new Mixer(engine, 4);
+		var sin1 = new Sine(engine, 440);
+		var sin2 = new Sine(engine, 659.25);
+		var sin3 = new Sine(engine, 523.25);
+		Node.connect(sin1, 0, mix, 0);
+		Node.connect(sin2, 0, mix, 1);
+		Node.connect(sin3, 0, mix, 2);
+		engine.setNode(mix);
 		for(int i = 0; i < 120; ++i) {
 			engine.refill();
 			Thread.sleep(20);

com/danitheskunk/skunkworks/audio/nodes/Mixer.java

@@ -0,0 +1,38 @@
+package com.danitheskunk.skunkworks.audio.nodes;
+
+import com.danitheskunk.skunkworks.audio.AudioBuffer;
+import com.danitheskunk.skunkworks.audio.AudioEngine;
+
+public class Mixer extends Node {
+	private int channels;
+
+	public Mixer(AudioEngine engine, int channels) {
+		super(engine, channels, 1);
+		this.channels = channels;
+	}
+
+	@Override
+	public AudioBuffer getBuffer(int slot) {
+		var bufs = new AudioBuffer[channels];
+		var bufferSize = getEngine().getBufferSize();
+		var buf = new AudioBuffer(bufferSize);
+
+		for(int channel = 0; channel < channels; ++channel) {
+			bufs[channel] = getBufferFromInput(channel);
+		}
+
+		for(int i = 0; i < bufferSize; ++i) {
+			double l = 0.0;
+			double r = 0.0;
+			for(var inBuf : bufs) {
+				if(inBuf != null) {
+					l += inBuf.getLeft(i);
+					r += inBuf.getRight(i);
+				}
+			}
+			//todo: dividing by channels just temporary mess
+			buf.setSample(i, l / channels, r / channels);
+		}
+		return buf;
+	}
+}

com/danitheskunk/skunkworks/audio/nodes/Node.java

@@ -56,4 +56,9 @@ public abstract class Node {
 	}
 
 	public abstract AudioBuffer getBuffer(int slot);
+
+	protected AudioBuffer getBufferFromInput(int inSlot) {
+		if(inConnections[inSlot] == null) return null;
+		return inConnections[inSlot].getBuffer(inConnectionSlots[inSlot]);
+	}
 }