Top Down Controller Unity

// This script is used to control the players movement on the X and Y axes.
using UnityEngine;
using System.Collections;

public class PlayerController2d2 : MonoBehaviour {

    /* Public variables which can be modified */

    // Allows us to set the player GameObject from the Inspector
    public GameObject playerGameObject;
    // Allows us to set the walking speed from the Inspector. A default value of 5 is assigned.
    public float walkingSpeed = 5;
    // Allows us to set the running speed from the Inspector. A default value of 10 is assigned.
    public float runningSpeed = 10;


    /* Private variables which can NOT be modified */

    // Private variables used to calculate the current speed and maximum speed
    private float currentSpeed;
    private float maxSpeed;
    // Private variables used in the script to determine which direction the player GameObject is moving
    private float velocityX;
    private float velocityY;


    // FixedUpdate is used to perform physics based actions
    void FixedUpdate()
    {

        // Determine if the Run button is being held down and if so sets the current speed to the runspeed
        // if the Run button is not being held down the current speed defaults to the walking speed
        // Make sure you define a Run button in the Input inspector!
        currentSpeed = (Input.GetButton("Run")) ? runningSpeed : walkingSpeed;


        // Move the player based on the Input Axis either Horizontally or Vertically
        playerGameObject.rigidbody2D.velocity = new Vector2(Mathf.Lerp(0, Input.GetAxis("Horizontal") * currentSpeed, 0.8f),
                                           Mathf.Lerp(0, Input.GetAxis("Vertical") * currentSpeed, 0.8f));


            // Determine which direction the player is being moved to determine which direction
            // the player GameObject needs to be rotated
            velocityX = Input.GetAxisRaw("Horizontal");
            velocityY = Input.GetAxisRaw("Vertical");

            // Rotate the player GameObject based on which way the player is being moved
            if (velocityX != 0 && velocityY != 0)
            {
                if (velocityX > 0 && velocityY > 0)
                {
                    playerGameObject.transform.rotation = Quaternion.Euler(new Vector3(0f, 0f, 135f));
                }
                else if (velocityX < 0 && velocityY < 0)
                {
                    playerGameObject.transform.rotation = Quaternion.Euler(new Vector3(0f, 0f, 315f));
                }
                else if (velocityX > 0 && velocityY < 0)
                {
                    playerGameObject.transform.rotation = Quaternion.Euler(new Vector3(0f, 0f, 45f));
                }
                else if (velocityX < 0 && velocityY > 0)
                {
                    playerGameObject.transform.rotation = Quaternion.Euler(new Vector3(0f, 0f, 225f));
                }
            }
            else if (velocityX != 0 && velocityX > 0)
            {
                playerGameObject.transform.rotation = Quaternion.Euler(new Vector3(0f, 0f, 90f));
            }
            else if (velocityX != 0 && velocityX < 0)
            {
                playerGameObject.transform.rotation = Quaternion.Euler(new Vector3(0f, 0f, 270f));
            }
            else if (velocityY != 0 && velocityY > 0)
            {
                playerGameObject.transform.rotation = Quaternion.Euler(new Vector3(0f, 0f, 180f));
            }
            else if (velocityY != 0 && velocityY < 0)
            {
                playerGameObject.transform.rotation = Quaternion.Euler(new Vector3(0f, 0f, 0f));
            }

            // Make sure that our player isn't moving faster than the running speed we have
            // defined in the Inspector
            if (currentSpeed > runningSpeed)
            {
                currentSpeed = runningSpeed;
            }
    }
}