Joystick.cs

using UnityEngine;
using UnityEngine.UI;
using UnityEngine.Events;
using UnityEngine.EventSystems;
using System.Collections;

#if UNITY_EDITOR
using UnityEditor;
#endif

namespace UnityEngine.UI {
    [AddComponentMenu("UI/Joystick", 36), RequireComponent(typeof(RectTransform))]
    public class Joystick : UIBehaviour, IBeginDragHandler, IEndDragHandler, IDragHandler {

        [SerializeField, Tooltip("The child graphic that will be moved around")]
        RectTransform _joystickGraphic;
        public RectTransform JoystickGraphic {
            get { return _joystickGraphic; }
            set {
                _joystickGraphic = value;
                UpdateJoystickGraphic();
            }
        }

//      [SerializeField]
        public Vector2 _axis;

        [SerializeField, Tooltip("How fast the joystick will go back to the center")]
        float _spring = 25;
        public float Spring {
            get { return _spring; }
            set { _spring = value; }
        }

        [SerializeField,  Tooltip("How close to the center that the axis will be output as 0")]
        float _deadZone = .1f;
        public float DeadZone {
            get { return _deadZone; }
            set { _deadZone = value; }
        }

        [Tooltip("Customize the output that is sent in OnValueChange")]
        public AnimationCurve outputCurve = new AnimationCurve(new Keyframe(0, 0, 1, 1), new Keyframe(1, 1, 1, 1));

        public JoystickMoveEvent OnValueChange;

        public Vector2 JoystickAxis {
            get {
                Vector2 outputPoint = _axis.magnitude > _deadZone ? _axis : Vector2.zero;
                float magnitude = outputPoint.magnitude;

                outputPoint *= outputCurve.Evaluate(magnitude);

                return outputPoint;
            }
            set { SetAxis(value); }
        }

        RectTransform _rectTransform;
        public RectTransform rectTransform {
            get {
                if(!_rectTransform) _rectTransform = transform as RectTransform;

                return _rectTransform;
            }
        }

        bool _isDragging;

        [HideInInspector]
        bool dontCallEvent;

        public void OnBeginDrag(PointerEventData eventData) {
            if(!IsActive())
                return;

            EventSystem.current.SetSelectedGameObject(gameObject, eventData);

            Vector2 newAxis = transform.InverseTransformPoint(eventData.position);

            newAxis.x /= rectTransform.sizeDelta.x * .5f;
            newAxis.y /= rectTransform.sizeDelta.y * .5f;

            SetAxis(newAxis);

            _isDragging = true;
            dontCallEvent = true;
        }

        public void OnEndDrag(PointerEventData eventData) {
            _isDragging = false;
        }

        public void OnDrag(PointerEventData eventData) {
            RectTransformUtility.ScreenPointToLocalPointInRectangle(rectTransform, eventData.position, eventData.pressEventCamera, out _axis);

            _axis.x /= rectTransform.sizeDelta.x * .5f;
            _axis.y /= rectTransform.sizeDelta.y * .5f;

            SetAxis(_axis);

            dontCallEvent = true;
        }

        void OnDeselect() {
            _isDragging = false;
        }


        void Update() {
            if(_isDragging)
                if(!dontCallEvent)
                    if(OnValueChange != null) OnValueChange.Invoke(JoystickAxis);
        }

        void LateUpdate() {
            if(!_isDragging)
                if(_axis != Vector2.zero) {
                    Vector2 newAxis = _axis - (_axis * Time.unscaledDeltaTime * _spring);

                    if(newAxis.sqrMagnitude <= .0001f)
                        newAxis = Vector2.zero;

                    SetAxis(newAxis);
                }

            dontCallEvent = false;
        }
        protected override void OnValidate() {
            base.OnValidate();
            UpdateJoystickGraphic();
        }


        public void SetAxis(Vector2 axis) {
            _axis = Vector2.ClampMagnitude(axis, 1);

            Vector2 outputPoint = _axis.magnitude > _deadZone ? _axis : Vector2.zero;
            float magnitude = outputPoint.magnitude;

            outputPoint *= outputCurve.Evaluate(magnitude);

            if(!dontCallEvent)
                if(OnValueChange != null)
                    OnValueChange.Invoke(outputPoint);

            UpdateJoystickGraphic();
        }

        void UpdateJoystickGraphic() {
            if(_joystickGraphic)
                _joystickGraphic.localPosition = _axis * Mathf.Max(rectTransform.sizeDelta.x, rectTransform.sizeDelta.y) * .5f;
        }

        [System.Serializable]
        public class JoystickMoveEvent : UnityEvent<Vector2> { }
    }
}

#if UNITY_EDITOR
static class JoystickGameObjectCreator {
    [MenuItem("GameObject/UI/Joystick", false, 2000)]
    static void Create() {
        GameObject go = new GameObject("Joystick", typeof(Joystick));

        Canvas canvas = Selection.activeGameObject ? Selection.activeGameObject.GetComponent<Canvas>() : null;

        Selection.activeGameObject = go;

        if(!canvas)
            canvas = Object.FindObjectOfType<Canvas>();

        if(!canvas) {
            canvas = new GameObject("Canvas", typeof(Canvas), typeof(RectTransform), typeof(GraphicRaycaster)).GetComponent<Canvas>();
            canvas.renderMode = RenderMode.ScreenSpaceOverlay;
        }

        if(canvas)
            go.transform.SetParent(canvas.transform, false);

        GameObject background = new GameObject("Background", typeof(Image));
        GameObject graphic = new GameObject("Graphic", typeof(Image));

        background.transform.SetParent(go.transform, false);
        graphic.transform.SetParent(go.transform, false);

        background.GetComponent<Image>().color = new Color(1, 1, 1, .86f);

        RectTransform backgroundTransform = graphic.transform as RectTransform;
        RectTransform graphicTransform = graphic.transform as RectTransform;

        graphicTransform.sizeDelta = backgroundTransform.sizeDelta * .5f;

        Joystick joystick = go.GetComponent<Joystick>();
        joystick.JoystickGraphic = graphicTransform;
    }
}
#endif