/*
 * Camera.cs
 * Authors: Bradley Blankenship
 * 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 Microsoft.Xna.Framework;

namespace tAC_Engine.Graphics.Cameras
{
	/// <summary>
	/// Represents the base for a series of Camera models, used for
	/// storing and keeping track of cameras
	/// </summary>
	public abstract class Camera
	{
		#region Fields

		/// <summary>
		/// The view matrix for the Camera
		/// </summary>
		protected Matrix mView = Matrix.Identity;

		/// <summary>
		/// The projection matrix for the camera
		/// </summary>
		protected Matrix mProjection = Matrix.Identity;

		/// <summary>
		/// The eye position of the camera
		/// </summary>
		protected Vector3 mEye = Vector3.Zero;

		/// <summary>
		/// The lookAt vector of the camera
		/// </summary>
		protected Vector3 mLookAt = Vector3.Forward;

		/// <summary>
		/// The up vector of the camera
		/// </summary>
		protected Vector3 mUp = Vector3.Up;

		#endregion

		#region Properties

		/// <summary>
		/// Gets the view matrix
		/// </summary>
		public Matrix View
		{
			get { return mView; }
		}

		/// <summary>
		/// Gets the projection matrix
		/// </summary>
		public Matrix Projection
		{
			get { return mProjection; }
		}

		/// <summary>
		/// Gets/Sets the position of the camera eye via three dimensions
		/// *Note* classes must override both getters and setters
		/// </summary>
		public abstract Vector3 Eye
		{
			get;
			set;
		}

		/// <summary>
		/// Gets/Sets the position of where the camera is looking at via three dimensions
		/// *Note* classes must override both getters and setters
		/// </summary>
		public abstract Vector3 LookAt
		{
			get;
			set;
		}

		/// <summary>
		/// Gets/Sets the direction of where up is relative to the camera via three dimensions
		/// *Note* classes must override both getters and setters
		/// </summary>
		public abstract Vector3 Up
		{
			get;
			set;
		}

		#endregion

		#region Helpers

		/// <summary>
		/// CreateView - Creates the view Matrix for the given Camera.
		/// </summary>
		protected virtual void CreateView()
		{
			// Create the view matrix
			mView = Matrix.CreateLookAt(mEye, mLookAt, mUp);
		}

		/// <summary>
		/// CreateProjection - Creates the projection Matrix for the given camera.
		/// </summary>
		protected abstract void CreateProjection();

		#endregion
	}
}