Working stepper motor with photodetector

gistfile1.txt

int Horizontal = 0; // set to home position

#include <Stepper.h>
const int stepsPerRevolution = 512;
Stepper Vstepper(stepsPerRevolution, 8, 9, 10, 11);
Stepper Ystepper(stepsPerRevolution, 1, 2, 3, 4);


// LDR
// name = analogpin;
int topleft= A3; // (red)
int bottomleft = A1; // (Blue)
int topright = A0; // (Green)
int bottomright= A2; // (Yellow)

void setup()
{
  Serial.begin(9600); //initialize serial port
  pinMode(8, OUTPUT);
  pinMode(9, OUTPUT);
  pinMode(10, OUTPUT);
  pinMode(11, OUTPUT);
  pinMode(1, OUTPUT);
  pinMode(2, OUTPUT);
  pinMode(3, OUTPUT);
  pinMode(4, OUTPUT);
  Vstepper.setSpeed(1200); // setting the speed of stepper 
  Ystepper.setSpeed(1200); // setting the speed of stepper 
}
void loop()
{
int tl = analogRead(topleft);
int tr = analogRead(topright);
int bl = analogRead(bottomleft);
int br = analogRead(bottomright);
int delayt = 25;
int sensitivity = 100;
int avgl = (tl + bl) / 2;
int avgr = (tr + br) / 2;
int avgt = (tl + tr) / 2;
int avgb = (bl + br) / 2;
int diffv = avgl - avgr; //diff between left n right
int diffh = avgt - avgb; //diff between top n bottom

if (-1* sensitivity > diffv || diffv > sensitivity) // check for difference in sensitivity
{
if (avgl > avgr) // if average left is greater than average right
{
Vstepper.step(stepsPerRevolution);
Ystepper.step(-stepsPerRevolution);

}
else // if the average left is smaller than average right
{
Vstepper.step(-stepsPerRevolution);
Ystepper.step(stepsPerRevolution);

}
}

else if (-1* sensitivity < diffv || diffv < sensitivity)
{
Vstepper.step(0);
Ystepper.step(0);
}

if (-1*sensitivity > diffh || diffh > sensitivity)
{
if (avgt > avgb)
{
Horizontal = -- Horizontal;
if (Horizontal < 0)
{
Horizontal = 0;
}
}

else if (avgt < avgb)
{
Horizontal = ++ Horizontal;
if (Horizontal > 180)
{
Horizontal = 180;
}
}
else if (avgt == avgb)
{
  //nothing
}
}
delay(delayt);
}