am having difficulties using panning in beads. I would like to be able to move the ellipse left/ right to change the pan position of the sound. Can anyone help me with this?

2. import beads.*;
3. 
   
4. AudioContext ac;
5. float x;
6. float y;
7. float d;
8. float dx;
9. float dy;
10. 
    
11. String sourceFile; // this will hold the path to our audio file
12. SamplePlayer sp; // the SamplePlayer class will be used to play the audio file
13. 
    
14. // standard gain objects
15. Gain g;
16. Glide gainValue;
17. 
    
18. Reverb r; // our Reverberation unit generator
19. 
    
20. Button buttons;
21. float rad=50;
22. 
    
23. void setup()
24. {
25.   size(800, 600);
26.   smooth();
27.   buttons= new Button(width/2, height/2);
28. 
    
29. 
    
30. 
    
31.   ac = new AudioContext(); // create our AudioContext
32. 
    
33.     sourceFile = sketchPath("") + "Drum_Loop_01.wav";
34. 
    
35.   // Try/Catch blocks will inform us if the file can't be found
36.   try {  
37.     // initialize our SamplePlayer, loading the file indicated by the sourceFile string
38.     sp = new SamplePlayer(ac, new Sample(sourceFile));
39.   }
40.   catch(Exception e)
41.   {
42.     // if there is an error, show an error message (at the bottom of the processing window)
43.     println("Exception while attempting to load sample!");
44.     e.printStackTrace(); // then print a technical description of the error
45.     exit(); // and exit the program
46.   }
47. 
    
48.   // we would like to play the sample multiple times, so we set KillOnEnd to false
49.   sp.setKillOnEnd(false);
50. 
    
51.   // as usual, we create a gain that will control the volume of our sample player
52.   gainValue = new Glide(ac, 0.0, 20);
53.   g = new Gain(ac, 1, gainValue);
54.   g.addInput(sp); // connect the filter to the gain
55. 
    
56.   r = new Reverb(ac, 1); // create a new reverb with a single output channel
57.   r.setSize(0.7); // set the room size (between 0 and 1) 0.5 is the default
58.   r.setDamping(0.5); // set the damping (between 0 and 1) - the higher the dampening, the fewer resonant high frequencies
59.   // You can also control a Reverb's early reflections and late reverb
60.   // to do so, use r.setEarlyReflectionsLevel(0-1); or r.setLateReverbLevel(0-1);
61.   r.addInput(g); // connect the gain to the reverb
62. 
    
63. 
    
64.   ac.out.addInput(r); // connect the Reverb to the AudioContext
65. 
    
66.   // remember, the reverb unit only outputs a reverberated signal
67.   // so if we want to hear the dry drums as well, then we will also need to connect
68.   // the SamplePlayer to the output
69.   ac.out.addInput(g); // connect the sp gain to the output
70. 
    
71.   ac.start(); // begin audio processing
72.   // sp.start();
73. 
    
74.   background(0); // draw a black background
75.   text("Click to hear a Reverb object in action.", 50, 50); // tell the user what to do
76. }
77. 
    
78. // although we're not drawing to the screen, we need to have a draw function
79. // in order to wait for mousePressed events
80. void draw() {
81.   background(10);
82.   dx=mouseX-width/2;
83.   dy=mouseY-height/2;
84.   float d = dist(0, 0, dx, dy);
85. 
    
86.   fill(0, 0, 255, 150);
87.   noStroke();
88.   ellipse(width/2, height/2, 50, 50);
89.   buttons.display();
90.   //buttons.resize();
91.   if (mousePressed&&keyPressed) {
92.     rad=d*2;
93.   }
94. 
    
95.   //if (key == '2') { rad *= 1.0; }
96.   // if (key == '1') { rad *= 0.9; }
97.   //rad=constrain (rad,50,200);
98. 
    
99.   float roomSize = map(rad, 50, 200, 0, 1);
100.   r.setSize(roomSize );
101.   rad=constrain (rad, 50, 200);
102. }
103. 
     
104. // this routine is called whenever a mouse button is pressed on the Processing sketch
105. void keyPressed() {
106. 
     
107.   if (key==' ') {
108.     gainValue.setValue(1); // set the gain based on mouse position
109.     sp.setToLoopStart(); // move the playback pointer to the first loop point (0.0)
110.     sp.start(); // play the audio file
111.   }
112. }
113. class Button {
114.   float x, y;
115.   //float rad;
116.   float h, s, b;
117.   float transparency;
118. 
     
119.   Button(float _cx, float _cy) {
120.     x = _cx;
121.     y = _cy;
122.     // rad = _radius;
123.     h=100;
124.     s=100;
125.     b=100;
126.     transparency=20;
127.     //stroke(2);
128.   }
129. 
     
130.   void display() {
131.     stroke(0.5);
132.     fill(0, 0, 255, transparency);
133.     stroke(50, 0, 255, 50);
134.     strokeWeight(2);
135.     ellipse (x, y, rad, rad);
136.   }
137. }