using System;

using OpenTK.Graphics.OpenGL;
using OpenTK.Graphics;
using OpenTK;

namespace org.niclasundharald.engine.graphics
{
	public class GLCamera : GLSceneOrientation
	{
		float fov;
		float width, height;

		Vector3 vPosition,
			vView,
			vTop;

		public GLCamera()
		{
			fov = MathHelper.PiOver2;
			width = 100;
			height = 100;

			vPosition = new Vector3(0,0,1000);
			vView = new Vector3(0,0,-1);
			vTop = new Vector3(0,1,0);

			buildProjection();
			buildMatrices();
		}

		public void setViewport(int width, int height)
		{
			this.width = (float)width;
			this.height = (float)height;

			buildProjection();
		}
		public void setFoV(float fov){
			this.fov = fov;
			buildProjection();
		}

		private void buildProjection(){
			_mProjection = Matrix4.CreatePerspectiveFieldOfView(
				fov,
				width / height,
				1.0f,
				100000.0f
				);			
		}

		public Vector3 Position
		{
			get { return new Vector3(vPosition); }
			set { this.vPosition = new Vector3(value); buildMatrices(); }
		}
		public Vector3 View
		{
			get { return new Vector3(vView); }
			set { this.vView = new Vector3(value).Normalized(); buildMatrices(); }
		}

		public Vector3 Top
		{
			get { return new Vector3(vTop); }
			set { this.vTop = new Vector3(value).Normalized(); buildMatrices(); }
		}

		private void buildMatrices(){
			
			Matrix4 mTranslation = Matrix4.CreateTranslation( -this.vPosition );
			Vector3 x,y,z;
			
			z = -vView;
			x = Vector3.Cross( vTop, z ).Normalized();
			y = Vector3.Cross( z, x );
			
			Matrix4 mRotation = new Matrix4(
										new Vector4(x,0),
										new Vector4(y,0),
										new Vector4(z,0),
										new Vector4(0,0,0,1)
										);
			mRotation.Transpose();
		
			_mCamera = mTranslation * mRotation;
		}


	}
}