Trying to get 2D X angle through 3D

Question

Im trying to make an aimbot for Call of duty 4 for educational purpose

I tried this: I declared a few variables enemy coords = eX, eY, eZ Player = pX, pY, pZ

Vector length for X, Z

I have 4 conditions if (eX <= pX && eZ < pZ) { VecX = pX - eX; VecZ = pZ - eZ; }

if (eX > pX && eZ <= pZ)
        {
            VecX = eX - pX;
            VecZ = pZ - eZ;
}

if (eX < pX && eZ >= pZ)
        {
            VecX = pX - eX;
            VecZ = eZ - pZ;

}


if (eX >= pX && eZ > pZ)
        {
            VecX = eX - pX;
            VecZ = eZ - pZ;


}

then

    angleA = atan(NSdif/EWdif) * 57.29578;

          angleP = (angleA/360);

    then I get X Value from the Code

   if (eX <= pX && eZ < pZ)
    {

angleA = atan(VecX/VecZ) * 57.29578;

  angleP = (angleA/360);



  newValue = halfCircle + (0xFFFFFFFF*angleP);

  newValue2 = newValue;

}

     if (eX > pX && eZ <= pZ)
                {
                    VecX = eX - pX;
                    VecZ = pZ - eZ;

    angleA = atan(VecX/VecZ) * 57.29578;

              angleP = (angleA/360);
    newValue = 0xFFFFFFFF - (0xFFFFFFFF*angleP);

        }

        if (eX < pX && eZ >= pZ)
                {
                    VecX = pX - eX;
                    VecZ = eZ - pZ;

angleA = atan(VecX/VecZ) * 57.29578;

          angleP = (angleA/360);

newValue = halfCircle - (0xFFFFFFFF*angleP);
        }


        if (eX >= pX && eZ > pZ)
                {
                    VecX = eX - pX;
                    VecZ = eZ - pZ;

angleA = atan(VecX/VecZ) * 57.29578;

          angleP = (angleA/360);

newValue = 0 + (0xFFFFFFFF*angleP);
        }

but this gives me far from what is the enemy X pos on screen ?