BallDragLaunch.cs

    using UnityEngine;
    using System.Collections;

    namespace UnityDevelopment.BowlMaster
    {
	[RequireComponent (typeof(Ball))]
	public class BallDragLaunch : MonoBehaviour
	{
		

		private Vector3 dragStart, dragEnd;
		private float startTime, endTime;
		private Ball ball;

		// Use this for initialization
		void Start ()
		{
			ball = GetComponent<Ball> ();
		}

		public void MoveStart (float amount)
		{
			if (!ball.inPlay) {
				float xPos = Mathf.Clamp (ball.transform.position.x + amount, -35f, 35f);
				float yPos = ball.transform.position.y;
				float zPos = ball.transform.position.z;
				ball.transform.position = new Vector3 (xPos, yPos, zPos);
			}
		}

		public void DragStart ()
		{
			if (!ball.inPlay) {
				// Capture time & position of drag start
				dragStart = Input.mousePosition;
				startTime = Time.time;
			}
		}

		public void DragEnd ()
		{
			if (!ball.inPlay) {
				// Launch the ball
				dragEnd = Input.mousePosition;
				endTime = Time.time;

				float dragDuration = endTime - startTime;
				float launchSpeedX = (dragEnd.x - dragStart.x) / dragDuration;
				float launchSpeedY = (dragEnd.y - dragStart.y) / dragDuration;
				float launchSpeedZ = (dragEnd.y - dragStart.y) / dragDuration;

				Vector3 launchVelocity = new Vector3 (launchSpeedX, -launchSpeedY, launchSpeedZ);
				ball.Launch (launchVelocity);
			}
		}
	}
    }