int dots = 1000;
  float[] dX = new float[dots];
  float[] dY = new float[dots];
  
  float l_0 = 0.0;
  float h_0 = 0.0;
  
  float legX = 0.0;
  float legY = 0.0;
  float thighX = 0.0;
  float thighY = 0.0;
  
  float l = 60.0; // Length of the 'leg'
  float h = 90.0; // Height of the 'leg'
  
  float nmx, nmy = 0.0;
  float mx, my = 0.0;
  
  int currentValue = 0;
  int valdir = 1;
  
  void setup() 
  {
    size(640, 360);
    noStroke();
    smooth();
    background(102);
  }
  
  void draw() 
  {
    // Smooth the mouse
    nmx = mouseX;
    nmy = mouseY;
    if((abs(mx - nmx) > 1.0) || (abs(my - nmy) > 1.0)) { 
      mx = mx - (mx-nmx)/20.0;
      my = my - (my-nmy)/20.0;
  
      // Set the drawing value
      currentValue += 1* valdir;
      if(currentValue > 255 || currentValue <= 0) {
        valdir *= -1;
      }
    }
  
    iKinematics();
    kinematics();
  
    pushMatrix();
    translate(width/2, height/2);
    stroke(currentValue); 
    line(thighX, thighY, legX, legY);
    popMatrix();
  
    stroke(255);
    point(legX + width/2, legY + height/2);
  }
  
  void kinematics() 
  {
    thighX = h*cos(h_0);
    thighY = h*sin(h_0);
    legX = thighX + l*cos(h_0 - l_0);
    legY = thighY + l*sin(h_0 - l_0);
  }
  
  void iKinematics()
  {
    float tx = mx - width/2.0;
    float ty = my - height/2.0;
    float c2 = (tx*tx + ty*ty - h*h - l*l)/(2*h*l); //in degrees
    float s2 = sqrt(abs(1 - c2*c2)); // the sign here determines the bend in the joint  
    l_0 = -atan2(s2, c2);
    h_0 = atan2(ty, tx) - atan2(l*s2, h+l*c2);
  }