/*
 * PerspectiveCamera2D.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>
	/// Creates a perspective camera with a fixed position and look at angle to 
	/// give an appearence of a 2D scene with depth
	/// </summary>
	public class Perspective2DCamera : PerspectiveCamera
	{
		#region Properties

		/// <summary>
		/// Gets/Sets the eye vector
		/// </summary>
		public override Vector3 Eye
		{
			get { return mEye; }
			set
			{
				// Check to see if we need to set values and recalculate
				if (mEye != value)
				{
					mLookAt -= mEye;
					mEye = value;
					mLookAt += mEye;
					CreateView();
				}
			}
		}

		/// <summary>
		/// Gets the look at vector
		/// </summary>
		public override Vector3 LookAt
		{
			get { return mLookAt; }
			// Do not allow overriding; this must stay the same for
			// a proper 2D camera.
			set { }	
		}

		/// <summary>
		/// Gets the up vector
		/// </summary>
		public override Vector3 Up
		{
			get { return mUp; }
			// Do not allow overriding; this must stay the same for
			// a proper 2D camera.
			set { }
		}

		#endregion

		#region Constructs

		/// <summary>
		/// Default Projection Camera with no values set.
		/// </summary>
		public Perspective2DCamera()
		{
			// Create the projection and view matrixes
			CreateView();
			CreateProjection();
		}

		/// <summary>
		/// Paramaterized Constructor for perspective camera.
		/// </summary>
		/// <param name="eye">The position vector of the camera</param>
		/// <param name="fov">The field of view, in radians</param>
		/// <param name="aspectRatio">The aspect ratio for the camera</param>
		/// <param name="near">The distance to the near plane</param>
		/// <param name="far">The distance to the far plane</param>
		public Perspective2DCamera(Vector3 eye, float fov, float aspectRatio,
								  float near, float far)
		{
			// Set all of the values
			mEye.X = eye.X; mEye.Y = eye.Y; mEye.Z = 0;
			mLookAt = Vector3.Forward + mEye;
			mUp = Vector3.Up;
			mFOV = fov;
			mAspectRatio = aspectRatio;
			mNear = near;
			mFar = far;

			// Create the view and projection matrixes
			CreateView();
			CreateProjection();
		}

		#endregion

		#region Helpers

		/// <summary>
		/// Creates the projection Matrix for the given camera.
		/// </summary>
		protected override void CreateProjection()
		{
			// Create the projection matrix
			mProjection = Matrix.CreatePerspectiveFieldOfView(mFOV,
				mAspectRatio, mNear, mFar);
		}

		#endregion
	}
}