/*
 * FollowCamera.cs
 * Authors:
 * Copyright (c) 2007-2008 Cornell University

 This program is free software; you can redistribute it and/or
 modify it under the terms of the GNU General Public License
 as published by the Free Software Foundation; either version 2
 of the License, or (at your option) any later version.

 This program is distributed in the hope that it will be useful,
 but WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 GNU General Public License for more details.

 You should have received a copy of the GNU General Public License
 along with this program; if not, write to the Free Software
 Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
*/

using System;
using System.Collections.Generic;
using System.Text;
using tAC_Engine.Graphics.Cameras;
using tAC_Engine.Graphics.Entities;
using Microsoft.Xna.Framework;

namespace tAC_Engine.Graphics.Cameras
{
	/// <summary>
	/// Defines a perspective 3D camera that follows a given object
	/// </summary>
	public class FollowCamera : Perspective3DCamera
	{
		#region Fields

		/// <summary>
		/// The amount of rotation along the x axis
		/// </summary>
		public float xRot;
		
		/// <summary>
		/// The amount of rotation along the y axis
		/// </summary>
		public float yRot;
		
		/// <summary>
		/// The amount of rotation along the z axis
		/// </summary>
		public float zRot;

		// Position offset
		Vector3 mOffset;

		// Model in which the camera follows
		EntityModel mFollow;

		#endregion

		#region Properties

		/// <summary>
		/// Gets/Sets the postion offset
		/// </summary>
		public Vector3 Offset
		{
			get { return mOffset; }
			set { mOffset = value; }
		}

		/// <summary>
		/// Gets/Sets the object in which the camera will follow
		/// </summary>
		public EntityModel Follow
		{
			get { return mFollow; }
			set { mFollow = value; }
		}

		#endregion

		#region Creation

		/// <summary>
		/// Creates a camera that will follow a model
		/// </summary>
		/// <param name="follow">the model to follow</param>
		/// <param name="offset">the distance the camrea will be away from the model</param>
		/// <param name="up">The direction in which up is for the camera</param>
		/// <param name="fov">The camera's field of view</param>
		/// <param name="aspectRatio">The apsect ratio (width to height) of the camera</param>
		/// <param name="near">How close to the camera rendering can start</param>
		/// <param name="far">How far from the camera rendering can go</param>
		public FollowCamera(EntityModel follow, Vector3 offset, Vector3 up, float fov, float aspectRatio, float near, float far)
			: base(Vector3.Zero, Vector3.Zero, up, fov, aspectRatio, near, far)
		{
			mFollow = follow;
			mOffset = offset;
			xRot = 0.0f;
			yRot = 0.0f;
			zRot = 0.0f;
		}

		/// <summary>
		/// Creates the angle at which the scene is viewed at to be displayed
		/// </summary>
		protected override void CreateView()
		{
			//base.CreateView();
			if (mFollow != null)
			{
				mEye = new Vector3(0, 5, 0);
				//mEye = Vector3.Transform(Offset, Matrix.CreateFromYawPitchRoll(mFollow.rotY, mFollow.rotX, mFollow.rotZ));
				// mEye = mEye + //mFollow.TransformationMatrix.Translation;
				Vector3 camUp = Up;
				//camUp = Vector3.Transform(camUp, Matrix.CreateFromYawPitchRoll(mFollow.rotY, mFollow.rotX, mFollow.rotZ));
				mView = Matrix.CreateLookAt(mEye, mFollow.TransformationMatrix.Translation, camUp);
			}
		}

		#endregion

		#region Update

		/// <summary>
		/// Updates the follow camera
		/// </summary>
		public void update()
		{
			CreateView();
		}

		#endregion
	}
}