Interesting rotation effect

src/AudioClient.java

@@ -1,8 +1,6 @@
 import com.xtaudio.xt.*;
 
 public class AudioClient {
-  private static double phase;
-
   public static void main(String[] args) throws Exception {
     int sampleRate = 192000;
 
@@ -20,31 +18,9 @@ public class AudioClient {
     AudioPlayer.addLine(l3);
     AudioPlayer.addLine(l4);
 
-    long startTime = System.currentTimeMillis();
-
     player.start();
     while (true) {
-      if (System.currentTimeMillis() - startTime > 1) {
-        float diff = nextSine(sampleRate, 100) / 1000f;
 
-        l1.setX1(l1.getX1() - diff);
-        l1.setX2(l1.getX2() + diff);
-        l2.setX1(l2.getX1() + diff);
-        l2.setX2(l2.getX2() + diff);
-        l3.setX1(l3.getX1() + diff);
-        l3.setX2(l3.getX2() - diff);
-        l4.setX1(l4.getX1() - diff);
-        l4.setX2(l4.getX2() - diff);
-
-        startTime = System.currentTimeMillis();
-      }
     }
   }
-
-  static float nextSine(double sampleRate, double frequency) {
-    phase += frequency / sampleRate;
-    if (phase >= 1.0)
-      phase = -1.0;
-    return (float) Math.sin(phase * Math.PI);
-  }
 }

src/AudioPlayer.java

@@ -10,6 +10,7 @@ public class AudioPlayer extends Thread {
   private static int currentLine = 0;
   private static float FREQUENCY = 440;
   private static int framesDrawn = 0;
+  private static double phase = 0;
 
   static void render(XtStream stream, Object input, Object output, int frames,
                      double time, long position, boolean timeValid, long error, Object user) {
@@ -17,6 +18,8 @@ public class AudioPlayer extends Thread {
 
     for (int f = 0; f < frames; f++) {
       Line line = currentLine();
+      line.rotate(nextTheta(stream.getFormat().mix.rate, 0.000001));
+
       int framesToDraw = (int) (line.length() * 100);
       int neg = line.getX1() < line.getX2() || line.getY1() < line.getY2() ? 1 : -1;
 
@@ -34,6 +37,13 @@ public class AudioPlayer extends Thread {
     }
   }
 
+  static float nextTheta(double sampleRate, double frequency) {
+    phase += frequency / sampleRate;
+    if (phase >= 1.0)
+      phase = -1.0;
+    return (float) (phase * Math.PI);
+  }
+
   public static void addLine(Line line) {
     AudioPlayer.lines.add(line);
   }

src/Line.java

@@ -16,6 +16,13 @@ public class Line {
     return (float) Math.sqrt(Math.pow(getX1() - getX2(), 2) + Math.pow(getY1() - getY2(), 2));
   }
 
+  public void rotate(double theta) {
+    setX1((float) (getX1() * Math.cos(theta) - getY1() * Math.sin(theta)));
+    setY1((float) (getX1() * Math.sin(theta) + getY1() * Math.cos(theta)));
+    setX2((float) (getX2() * Math.cos(theta) - getY2() * Math.sin(theta)));
+    setY2((float) (getX2() * Math.sin(theta) + getY2() * Math.cos(theta)));
+  }
+
   public Point getA() {
     return a;
   }