i'm having trouble to control  my pong's paddle with a potentiometer, for those of you non-electronic people, you can still help me as my problem lies in processing.
my goal is to succesfully read the serial port and use it's information to control the paddle's position.

this is the code, english speakers please ignore my spanish comments:

1. import processing.serial.*;
2. Serial port;
3. Ball myBall;        //declaro objeto Ball
4. Paddle myPaddle1;    //declaro objeto Paddle1
5. Paddle myPaddle2;
6. int score1;
7. int score2;
8. float yposPot;
9. float yposBall;
10. float yposPaddle;
11. float yposPaddleR;
12. float yposPaddleL;
13. void setup()
14.   {
15.    size(1000, 500);                        //declaro tamaño
16.    myBall = new Ball(500, 250, 20, 1);    //creo Ball
17.    myPaddle1 = new Paddle(true, false, false, false, true, 0);  //creo Paddle1
18.    myPaddle2 = new Paddle(false, true, false, true, false, 0); //creo paddle2
19.    score1 = 0;
20.    score2 = 0;
21.    serial();
22.    }
23.    
24. void draw()
25.   {
26.    cancha();                  //dibuja todo lo relacionado a la cancha
27.    myBall.calculate();        // calcula la posicion de la pelota y sus rebotes
28.    myBall.display();          //dibuja la pelota
29.    myPaddle1.calculate();      //calcula la posicion de la paleta1
30.    myPaddle1.display();        //dibuja la paleta1
31.    myPaddle2.calculate();      //calcula la posicion de la paleta2
32.    myPaddle2.display();        //dibuja la paleta2
33.   }
34.  
35. void cancha()
36.   {
37.    background(0); //fondo negro 
38.    PFont font = loadFont("Serif-70.vlw"); //carga fuente
39.    textFont(font, 70); //setea el tamaño de la fuente
40.    fill(255, 255, 255, 180); //dibuja blanco transparente
41.    text(score1, width/2-100, 100);   //dibuja el puntaje del jugador 1
42.    text(score2, width/2+70, 100); //dibuja el puntaje del jugador 2
43.    rectMode(CENTER);
44.    rect(width/2, 50, 10, 75);
45.    rect(width/2, 150, 10, 75);    //estos rectangulos dibujan la linea punteada del medio
46.    rect(width/2, 250, 10, 75);
47.    rect(width/2, 350, 10, 75);
48.    rect(width/2, 450, 10, 75);
49.   }
50.  
51. class Ball
52.   {
53.    float xpos;          //declara la posicion a lo ancho
54.    float ypos;          //declara la posicion a lo alto
55.    float xspeed;        //declara la variacion de la posicion a lo ancho
56.    float yspeed;        //declara la variacion de la posicion a lo alto
57.   
58.    Ball(float tempXpos, float tempYpos, float tempXspeed, float tempYspeed) //constructor
59.      {
60.        xpos = tempXpos;
61.        ypos = tempYpos;               
62.        xspeed = tempXspeed;
63.        yspeed = tempYspeed;
64.       }
65.    void calculate() //hace todos los calculos referentes a la posicion de la pelota
66.      { xpos = xpos + xspeed;  //refresca la posicion a lo ancho de acerdo a la velocidad
67.        ypos = ypos + yspeed;  //refresca la posicion a lo alto de acuerdo a la velocidad
68.        if(xpos<500)yposPaddle=yposPaddleL;
69.        if(xpos>500)yposPaddle=yposPaddleR;
70.       
71.        if(xpos>=925)    //que pasa cuando la pelota llega a la derecha
72.          {if(ypos <= yposPaddle + 50 && ypos >= yposPaddle - 50)   //si la pelota choca contra la paleta
73.            {
74.          
75.             if(ypos<= yposPaddle + 50)   //si pega en la parte baja
76.               {yspeed=map(ypos, yposPaddle, yposPaddle + 50, 1, 15);   // y rebota hacia abajo
77.               xspeed=-20;          //velocidad de x al rebotar              
78.               }
79.              else if(ypos >= yposPaddle -50)  //si pega en la parte alta
80.                {
81.                 xspeed=-20;    //velocidad de x al rebotar
82.                 yspeed=map(ypos, yposPaddle, yposPaddle - 50, -1, -15); //y rebota hacia arriba
83.                } 
84.              }
85.           if((ypos> yposPaddle + 50 && xpos>=988) || (ypos < yposPaddle -50 && xpos>=988))   //si la paleta no alcanza a la pelota
86.              {score1();   //punto
87.              }    
88.           
89.          }
90.        if(xpos<=75)                                //que pasa cuando la pelota llega a la izquierda
91.          {if(ypos <= yposPaddle + 50 && ypos >= yposPaddle - 50)   //si la pelota choca contra la paleta
92.            {
93.          
94.             if(ypos<= yposPaddle + 50)   //si pega en la parte baja
95.               {yspeed=map(ypos, yposPaddle, yposPaddle + 50, 1, 15);   // y rebota hacia abajo
96.               xspeed=20;          //velocidad de x al rebotar              
97.               }
98.              else if(ypos >= yposPaddle -50)  //si pega en la parte alta
99.                {
100.                 xspeed=20;    //velocidad de x al rebotar
101.                 yspeed=map(ypos, yposPaddle, yposPaddle - 50, -1, -15); //y rebota hacia arriba
102.                } 
103.              }
104.           if((ypos> yposPaddle + 50 && xpos<=12) || (ypos < yposPaddle -50 && xpos<=12))   //si la paleta no alcanza a la pelota
105.              {score2();   //punto
106.              }    
107.          }
108.         
109.        if(ypos>=475)yspeed=-yspeed; // rebotes contra el piso
110.        if(ypos<=25)yspeed=-yspeed;  //rebotes contra el techo
111.        yposBall = ypos;
112.           
113.      }
114.     
115.    void score1()    //se activa cuando hay punto
116.      {
117.       score1 ++;   //suma un pùnto
118.       xpos=750;    //pone la pelota en el medio del eje x
119.       ypos=250;    //pone la pelota en el medio del eje y
120.       delay(100);
121.       xspeed=-15;  //asigna nueva velocidad en x
122.       yspeed=15-random(30);   //asigna nueva velocidad en y
123.       } 
124.     
125.    void score2()    //se activa cuando hay punto
126.      {
127.       score2 ++;   //suma un pùnto
128.       xpos=250;    //pone la pelota en el medio del eje x
129.       ypos=250;    //pone la pelota en el medio del eje y
130.       delay(100);     
131.       xspeed=15;  //asigna nueva velocidad en x
132.       yspeed=15-random(30);   //asigna nueva velocidad en y
133.       }
134.   
135.    void display()
136.      {
137.      noStroke();    //desactiva el contorno
138.      fill(255);     //dibuja en blanco
139.      ellipse(xpos, ypos, 50, 50);  //dibuja un elipse de tamaño 50x50 cuya posicion esta dada por xpos e ypos
140.      }
141.  
142.   } 
143. class Paddle
144.   {
145.    boolean side;    //define si la paleta va a estar a la derecha o la izquierda
146.    boolean manual;
147.    boolean mouse;
148.    boolean potentiometer;
149.    boolean ai;
150.    float ypos;
151.  
152.   Paddle (boolean tempSide, boolean tempManual,boolean tempMouse, boolean tempPotentiometer, boolean tempAi, float tempYpos) //constructor
153.     {
154.      side = tempSide;
155.      manual = tempManual;
156.      mouse = tempMouse;
157.      potentiometer = tempPotentiometer;
158.      ai = tempAi;
159.      ypos = tempYpos;
160.     }
161.  
162.   void calculate()
163.     {if(manual==true)//si se activa el modo manual
164.        {
165.         if(mouse==true)
166.          {
167.           ypos = constrain(mouseY, 50, 450); //evita que la paleta se dibuje a medias al llegar a un costado
168.           if(side==false)yposPaddleL = ypos;   
169.           else if(side==true)yposPaddleR = ypos;       
170.          }
171.         if(potentiometer==true)
172.           {
173.           ypos = yposPot;       
174.           if(side==false)yposPaddleL = ypos;   
175.           else if(side==true)yposPaddleR = ypos;  
176.           
177.           } 
178.        }
179.      if(ai==true)    //si se activa el BOT
180.        {ypos = constrain (ypos +(yposBall-ypos)*0.01, 50, 450); //sigue a la pelota
181.        if(side==false)yposPaddleL = ypos;
182.        else if(side==true)yposPaddleR = ypos;
183.       
184.        }
185.     
186.     }
187.  
188.   void display()  //funcion encargada de dibujar
189.     {noStroke();  //desactiva los contornos
190.      fill(255);   //dibuja en blanco
191.      rectMode(CENTER); //setea la manera de dibujar los rectangulos
192.      if(side==false) rect(25, ypos, 50, 100); //dibuja la paleta izquierda
193.      else rect(975, ypos, 50, 100);      //dibuja la paleta derecha
194.     }
195.   }
196. void serial ()
197.   {    
198.    port = new Serial(this, "/dev/tty.usbserial-A700fjm3", 9600);       
199.    port.bufferUntil('\n');
200.   }
201. void serialEvent (Serial port)
202.  {
203.   float ypos = (port.readStringUntil('\n');
204.   yposPot = map(ypos, 0, 1023, 50, 450);
205.  }

the error appears right between 142 line and 143.
i realised that if i coment lines 201 to 205 the error dissapears, but then i'm not able to read the serial port

i've been trying to implement sobel filter but runned into trouble with the output, wrote println to monitor it and saw that results aren't constraining as i want, here is the code:

1.  PImage img;
   int w = 160;
   
   // It's possible to perform a convolution
   // the image with different matrices
   
   float[][] V1matrix = { { -1,  0,  1 },                       
                                            { -2,  0,  2 },
                                            { -1,  0,  1 } };
                        
   float[][] V2matrix = { {  1,  0, -1 },
                                            {  2,  0, -2 },
                                            {  1,  0, -1 } };                      
                       
   float[][] H1matrix = { { -1, -2, -1 },     
                                            {  0,  0,  0 },
                                            {  1,  2,  1 } };                  
                       
   float[][] H2matrix = { {  1,  2,  1 },
                                            {  0,  0,  0 },
                                            { -1, -2, -1 } };                        
                      
   
   void setup() {
     size(500, 500);
     frameRate(30);
     img = loadImage("clock.jpg");
   }
   
   void draw() {
     // We're only going to process a portion of the image
     // so let's set the whole image as the background first
     image(img,0,0);
     // Where is the small rectangle we will process
     int xstart = constrain(mouseX-w/2,0,img.width);
     int ystart = constrain(mouseY-w/2,0,img.height);
     int xend = constrain(mouseX+w/2,0,img.width);
     int yend = constrain(mouseY+w/2,0,img.height);
     int matrixsize = 3;
    
     loadPixels();
     // Begin our loop for every pixel
     for (int x = xstart; x < xend; x++) {
       for (int y = ystart; y < yend; y++ ) {
         // Each pixel location (x,y) gets passed into a function called convolution()
         // which returns a new color value to be displayed.
         color c = convolution(x,y,V1matrix,V2matrix,H1matrix,H2matrix,matrixsize,img);
         int loc = x + y*img.width;
         pixels[loc] = c;
        
       }
     }
     int mouseLoc = mouseX+mouseY*width;
     println("(x="+mouseX+"|y="+mouseY+")==> color="+pixels[mouseLoc]);
     updatePixels();
   
   
   }
   
   color convolution(int x, int y, float[][] V1matrix, float[][] V2matrix,float[][] H1matrix,float[][] H2matrix, int matrixsize, PImage img) {
     float r1total = 0.0;
     float g1total = 0.0;
     float b1total = 0.0;
     float r2total = 0.0;
     float g2total = 0.0;
     float b2total = 0.0;
     int offset = matrixsize / 2;
     // Loop through convolution matrix
     for (int i = 0; i < matrixsize; i++){
       for (int j= 0; j < matrixsize; j++){
         // What pixel are we testing
         int xloc = x+i-offset;
         int yloc = y+j-offset;
         int loc = xloc + img.width*yloc;
         // Make sure we have not walked off the edge of the pixel array
         loc = constrain(loc,0,img.pixels.length-1);
         // Calculate the convolution
         // We sum all the neighboring pixels multiplied by the values in the convolution matrix.
         r1total += (red(img.pixels[loc]) * V1matrix[i][j]);
         g1total += (green(img.pixels[loc]) * V1matrix[i][j]);
         b1total += (blue(img.pixels[loc]) * V1matrix[i][j]);
        
         r2total += (red(img.pixels[loc]) * V2matrix[i][j]);
         g2total += (green(img.pixels[loc]) * V2matrix[i][j]);
         b2total += (blue(img.pixels[loc]) * V2matrix[i][j]);
        
         r1total += (red(img.pixels[loc]) * H1matrix[i][j]);
         g1total += (green(img.pixels[loc]) * H1matrix[i][j]);
         b1total += (blue(img.pixels[loc]) * H1matrix[i][j]);
              
         r2total += (red(img.pixels[loc]) * H2matrix[i][j]);
         g2total += (green(img.pixels[loc]) * H2matrix[i][j]);
         b2total += (blue(img.pixels[loc]) * H2matrix[i][j]);
       }
     }
     // Make sure RGB is within range (this is the part that won't work)
     r1total = constrain(r1total, 0, 255);
     g1total = constrain(g1total, 0, 255);
     b1total = constrain(b1total, 0, 255);
     r2total = constrain(r2total, 0, 255);
     g2total = constrain(g2total, 0, 255);
     b2total = constrain(b2total, 0, 255);
     // Return the resulting color, choose 1 or 2
     return color(r1total,g1total,b1total);
   }

PD: sorry about that quote, don't know how to remove it
PD2: sorry about my bad english

i took some code out of the tutorial and modificated it a little bit, i keep getting the error "ArrayIndexOutOfBoundsException: 25600" don't know what it means so i can't fix it could anyone help me?
here is the program:
PImage img;

void setup() {
  size(200, 200);
  img = loadImage("fox1.jpg"); //this image's size is 200x200 so it should fit perfectly
}

void draw() {
  loadPixels();
  // Since we are going to access the image's pixels too 
  img.loadPixels();
  for (int y = 0; y < height; y++) {
    for (int x = 0; x < width; x++) {
      int loc = x + y*width;
     
      // The functions red(), green(), and blue() pull out the 3 color components from a pixel.
      float r = red(img.pixels[loc]);
      float g = green(img.pixels[loc]);
      float b = blue(img.pixels[loc]);
     
      // Image Processing would go here
      // If we were to change the RGB values, we would do it here, before setting the pixel in the display window.
     
      // Set the display pixel to the image pixel
      pixels[loc] =  color(r,g,b);         
    }
  }
  updatePixels();
}

i decided to run processing on android and went to this sites to learn how to:
- http://developer.android.com/sdk/installing.html
- http://wiki.processing.org/w/Android
- http://createdigitalmotion.com/2010/09/getting-started-with-processing-for-android/
i followed every step but when i press run button, i keep getting this error:
"the google APIs are not installed properly"
i checked everything several times and still can't find were is my error.
does anyone know from a more detailed tutorial or has some experience with this problem?
hours have passed and i still can't find an answer, i will preciate your help

i recently wrote some code but no matter what, i keep receiving the message above.
here, what i wrote:

Paddle myPaddle;

void setup()
  {size(500, 500);
  myPaddle = new Paddle(0);  //======> this line apears highlighted when i click run button
  }

void draw()
  {background(0);
  myPaddle.display(); 
  }
 
class Paddle
  {
   boolean side;
 
 
  Paddle (boolean tempSide)
    {
     side = tempSide;
    }
 
  void display()
    {noStroke();
     fill(255);
     rectMode(CENTER);
     if(side==0) rect(25, mouseY, 50, 100);
     else rect(475, mouseY, 50, 100);
    }
  }

hello everyone,
I'm a newbie here and i recently tried to use integer variables inside of a rect (i'm using CORNERS mode). to my surprise, when i do this nothing happens.
i then used point, tried to put a random value and an int like this
point(x, int);
and then i see a point(x, 0) even if the int's value isn't 0.

hope you can help me.


this is the whole program:


int x1 = width/4 ;
int y1 = height/4 ;
int x2 = width*3/4 ;
int y2 = height*3/4 ;
int x3 = mouseX-width/4 ;
int y3 = mouseY-height/4 ;
int x4 = mouseX+width/4 ;
int y4 = mouseY+height/4 ;

void setup()
  {size(500, 500);
  stroke(255);
  rectMode(CORNERS); 
  noFill();
  }
 
void draw()
  {  background(0);
 
     rect(x1, y1, x2, y2);
     
     line(x1, y1, x3, y3);
     line(x1, y2, x3, y4);
     line(x2, y1, x4, y3);
     line(x2, y2, x4, y4);
    
    
     rect(x3, y3, x4, y4);
  
   
  }

thanks for reading.