/*
 * OrthographicCamera.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>
	/// Defines an orthographic camera to give a 2D visual effect
	/// </summary>
	public class OrthographicCamera : Camera
	{
		#region Fields

		// The width of the screen
		float mWidth;

		// The height of the screen
		float mHeight;

		// The near plane distance
		float mNear;

		// The far plane distance
		float mFar;

		#endregion

		#region Properties

		/// <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 { }	
		}

		/// <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)
				{
					// Alter the lookAt
					mLookAt -= mEye;
					mEye = value;
					mLookAt += mEye;
					CreateView();
				}
			}
		}

		/// <summary>
		/// Gets/Sets the screen width
		/// </summary>
		public float Width
		{
			get { return mWidth; }
			set
			{
				// Check to see if we need to recalculate the camera projection
				if (mWidth != value)
				{
					mWidth = value;
					CreateProjection();
				}
			}
		}

		/// <summary>
		/// Gets/Sets the screen height
		/// </summary>
		public float Height
		{
			get { return mHeight; }
			set
			{
				// Check to see if we need to recalculate the camera projection
				if (mHeight != value)
				{
					mHeight = value;
					CreateProjection();
				}
			}
		}

		/// <summary>
		/// Gets/Sets the distance to the near plane
		/// </summary>
		public float Near
		{
			get { return mNear; }
			set
			{
				// Check to see if we need to recalculate the camera projection
				if (mNear != value)
				{
					mNear = value;
					CreateProjection();
				}
			}
		}

		/// <summary>
		/// Gets/Sets the distance to the far plane
		/// </summary>
		public float Far
		{
			get { return mFar; }
			set
			{
				// Check to see if we need to recalculate the camera projection
				if (mFar != value)
				{
					mFar = value;
					CreateProjection();
				}
			}
		}

		#endregion

		#region Constructs

		/// <summary>
		/// Basic constructor
		/// </summary>
		public OrthographicCamera()
		{
			// Create the view and projection matrices
			CreateView();
			CreateProjection();
		}

		/// <summary>
		/// Paramaterized constructor
		/// </summary>
		/// <param name="eye">Position of where the camera eye is</param>
		/// <param name="width">Width of the projection field</param>
		/// <param name="height">Height of the projection field</param>
		/// <param name="near">Distance to the near plane</param>
		/// <param name="far">Distance to the far plane</param>
		public OrthographicCamera(Vector3 eye, float width, float height,
			float near, float far)
		{
			// Set the values
			mEye = eye;
			mLookAt = Vector3.Forward + mEye;
			mUp = Vector3.Up;
			mWidth = width;
			mHeight = height;
			mNear = near;
			mFar = far;

			// Create the views and projection matrices
			CreateView();
			CreateProjection();
		}


		#endregion

		#region Helpers

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

		#endregion
	}
}