scroll.cs

using System.Collections.Generic;
using UnityEngine;
using System.Collections;

[RequireComponent(typeof(SelectLevelDataSource))]
public class SelectLevelSwipe : MonoBehaviour, IGuiMove, IGuiTouch
{
  const float SWIPE_MAX_DURATION = 0.3f;

	//**************************************************************************
	//
	// Public for inspector
	//
	//**************************************************************************
	
	public float height = 8f;
	
	public float kinectSpeed = 0.95f;
	public float kinectMaxVelocity = 0.4f;

	//**************************************************************************
	//
	// MonoBehaviour
	//
	//**************************************************************************

	void Awake()
	{
		swipeArea = gameObject.GetComponent<BoxCollider>() ?? gameObject.AddComponent<BoxCollider>();
		swipeArea.isTrigger = true;

		selectLevelDataSource = gameObject.GetComponent<SelectLevelDataSource>();

		if(selectLevelDataSource == null) {
			Debug.LogError("select level data source component not found");
		}
	}

	//--------------------------------------------------------------------------

	void Update()
	{
		if(dragInfo.Count > 0) {
			DragInfo info = dragInfo.Peek();
			if(Time.time - info.time > SWIPE_MAX_DURATION) {
				dragInfo.Dequeue();
			}
		}

		CalculateVisibleArea();
		CalculateScrollableArea();
		CalculateSwapeArea();
	}

	//------------------------------------------------------------------------
	
	void FixedUpdate()
	{	
		velocity = velocity * kinectSpeed;

		if (Mathf.Abs(velocity) < 0.02f)
		{
			velocity = 0f;
			return;
		}

		float velocityAdd = velocity;

		if (Mathf.Abs(velocity) > kinectMaxVelocity) {
			int sign = velocity < 0 ? -1 : 1;
			velocityAdd = sign * kinectMaxVelocity;
		}

		Vector3 targetPosition = transformPosition + new Vector3(velocityAdd, 0f);
		transformPosition = AllowedTransformPosition(targetPosition);
	}

	//------------------------------------------------------------------------

	void OnDrawGizmos()
	{
		Gizmos.color = Color.red;
		Gizmos.DrawWireCube(visibleArea.center, new Vector3(visibleArea.width, visibleArea.height));

		Gizmos.color = Color.cyan;
		Gizmos.DrawWireCube(scrollableArea.center, new Vector3(scrollableArea.width, scrollableArea.height));
	}

	//**************************************************************************
	//
	// Runtime Interactive
	//
	//**************************************************************************

	//**************************************************************************
	// On touch begin

	public void OnGuiTouchBegin(Vector3 position)
	{
		velocity = 0f;
		tochBeginPosition = transformPosition - TransformFromScreenPoint(position);
	}

	//**************************************************************************
	// On touch move

	public void OnGuiTouchMove(Vector3 position)
	{
		Vector3 targetPosition = tochBeginPosition + TransformFromScreenPoint(position);
		targetPosition = AllowedTransformPosition(targetPosition);
		transformPosition = targetPosition;

		EnqueueDragInfo(position);
	}

	//**************************************************************************
	// On touch end

	public void OnGuiTouchEnd(Vector3 currentPosition)
	{
		if(dragInfo.Count == 0) return;

		DragInfo firstDraginfo = dragInfo.Dequeue();

		float currentTime = Time.time;

		float firstTime = firstDraginfo.time;
		Vector3 firstPosition = firstDraginfo.position;

		Vector3 differencePosition =  currentPosition - firstPosition;
		float differenceTime = (currentTime - firstTime) * 1000;

		velocity = differencePosition.x / differenceTime;

		dragInfo.Clear();
	}

	//-----------------------------------------------------------------------

	public void OnGuiTouchDismiss()
	{
		
	}

	//**************************************************************************
	//
	// Private
	//
	//**************************************************************************

	private Vector3 tochBeginPosition = Vector3.zero;
	private float velocity;
	private Queue<DragInfo> dragInfo = new Queue<DragInfo>();

	private SelectLevelDataSource selectLevelDataSource;

	private BoxCollider swipeArea;

	private Rect scrollableArea;
	private Rect visibleArea;

	// Cache 
	private float cachedCameraAspect;

	private Vector3 transformPosition
	{
		get { return transform.position; }
		set { transform.position =new Vector3(value.x, 0); }
	}

	//-----------------------------------------------------------------------

	private void CalculateScrollableArea()
	{
		scrollableArea = new Rect(visibleArea.x + transform.position.x, -visibleArea.height / 2f, selectLevelDataSource.GetWidth(), visibleArea.height);
	}

	//----------------------------------------------------------------------

	private void CalculateVisibleArea()
	{
		if (Mathf.Approximately(cachedCameraAspect, Camera.main.aspect)) return;

		visibleArea = new Rect(-(Const.MENU_DEFAULT_HEIGHT * Camera.main.aspect) / 2f, -height / 2f, Const.MENU_DEFAULT_HEIGHT * Camera.main.aspect, height);
		cachedCameraAspect = Camera.main.aspect;
	}

	//-------------------------------------------------------------------------

	private void CalculateSwapeArea()
	{
		swipeArea.center = new Vector3(-transform.position.x, 0f);
		swipeArea.size = new Vector3(visibleArea.width, visibleArea.height, 1f);
	}
	
	//--------------------------------------------------------------------------

	private Vector3 TransformFromScreenPoint(Vector3 screenPoint)
	{
		Vector3 viewportPoint = Camera.main.ScreenToViewportPoint(screenPoint);
		return new Vector3(viewportPoint.x * visibleArea.width, viewportPoint.y * visibleArea.height, 0f);
	}

	//-------------------------------------------------------------------------

	private Vector3 AllowedTransformPosition(Vector3 position)
	{
		Vector3 allowedPosition = position;

		allowedPosition = Vector3.Max(new Vector3(visibleArea.width - scrollableArea.width, 0f), allowedPosition);
		allowedPosition = Vector3.Min(new Vector3(0f, 0f), allowedPosition);

		return allowedPosition;
	}

	//--------------------------------------------------------------------------

	private void EnqueueDragInfo(Vector3 position)
	{
		DragInfo info = new DragInfo();
		info.position = position;
		info.time = Time.time;
		dragInfo.Enqueue(info);
	}

	//**************************************************************************
	//
	// DragInfo
	//
	//**************************************************************************

	private struct DragInfo
	{
		public float time;
		public Vector3 position;
	}
}