Untitled

using UnityEngine;
using System.Collections;

public class MotionControl : MonoBehaviour
{
    public GUIStyle MyStyle;
    public Texture Joystick;
    private float translationZ = 0f;
    private float translationX = 0f;

    void OnGUI()
    {
        GUI.Button(new Rect(0, Screen.height - Joystick.height, Joystick.width, Joystick.height), Joystick, MyStyle);
    }

    // Use this for initialization
    private void Start()
    {
    }

    public float speed = 100.0F;


    private void Update()
    {
        translationZ = Input.GetAxis("Vertical") * speed;
        translationX = Input.GetAxis("Horizontal") * speed;

        if (Input.GetMouseButton(0))
        {
            Debug.Log(Input.mousePosition.x < Joystick.width);
            if ((Input.mousePosition.y < Joystick.height) && (Input.mousePosition.x < Joystick.width))
            {
                translationZ = (Input.mousePosition.y - Joystick.height/2)*speed/20;
                translationX = (Input.mousePosition.x - Joystick.width/2)*speed/20;
            }
        }
        translationZ *= Time.deltaTime;
        translationX *= Time.deltaTime;

        transform.Translate(translationX, 0, translationZ);

    }
}