using System;

using System.Collections.Generic;

using Microsoft.Xna.Framework;

using Microsoft.Xna.Framework.Content;

using Microsoft.Xna.Framework.GamerServices;

using Microsoft.Xna.Framework.Graphics;

using Microsoft.Xna.Framework.Input;

public class GameClass : Microsoft.Xna.Framework.Game

{

    GraphicsDeviceManager graphics;

    public GameClass()

    {

        graphics = new GraphicsDeviceManager(this);

    }

    // ** 2DLINE ** 2DLINE ** 2DLINE ** 2DLINE ** 2DLINE ** 2DLINE ** 2DLINE ** 2DLINE

    // ** 2DLINE ** 2DLINE ** 2DLINE ** 2DLINE ** 2DLINE ** 2DLINE ** 2DLINE ** 2DLINE

    public void DrawLine2D(Vector2 from, Vector2 to, Color colour)

    {

        VertexPositionColor[]

        pnts = {new VertexPositionColor(new Vector3(from.X, from.Y, 0), colour),

                new VertexPositionColor(new Vector3(to.X,   to.Y,   0), colour)};

        VertexDeclaration

        basicEffectVertexDeclaration

        = new VertexDeclaration(graphics.GraphicsDevice, VertexPositionColor.VertexElements);

        BasicEffect basicEffect;

        basicEffect = new BasicEffect(graphics.GraphicsDevice, null);

        basicEffect.Alpha = 1.0f;

        basicEffect.VertexColorEnabled = true;

        basicEffect.TextureEnabled = false;

        basicEffect.Projection = Matrix.CreateOrthographicOffCenter(0.0F,

                                            graphics.GraphicsDevice.Viewport.Width,

                                            graphics.GraphicsDevice.Viewport.Height, 0.0f,

                                            0.0F, -1.0F);

        basicEffect.View = Matrix.Identity;

        basicEffect.World = Matrix.Identity;

        graphics.GraphicsDevice.VertexDeclaration       = basicEffectVertexDeclaration;

        graphics.GraphicsDevice.RenderState.PointSize   = 2; // Line Thickness

        graphics.GraphicsDevice.RenderState.FillMode    = FillMode.Solid;

        graphics.GraphicsDevice.RenderState.CullMode = CullMode.None;

        graphics.GraphicsDevice.VertexDeclaration = basicEffectVertexDeclaration;

        basicEffect.Begin();

        foreach (EffectPass pass in basicEffect.CurrentTechnique.Passes)

        {

            pass.Begin();

            graphics.GraphicsDevice.DrawUserPrimitives<VertexPositionColor>(

                        PrimitiveType.LineList,

                        pnts, 0, 1);

            pass.End();

        }

        basicEffect.End();

    }// End DrawQuad(..)

    // ** 2DLINE ** 2DLINE ** 2DLINE ** 2DLINE ** 2DLINE ** 2DLINE ** 2DLINE ** 2DLINE

    // ** 2DLINE ** 2DLINE ** 2DLINE ** 2DLINE ** 2DLINE ** 2DLINE ** 2DLINE ** 2DLINE

    protected override void Update(GameTime gameTime)

    {

        // Allows the game to exit

        if (GamePad.GetState(PlayerIndex.One).Buttons.Back == ButtonState.Pressed)

            this.Exit();

        base.Update(gameTime);

    }

    protected override void Draw(GameTime gameTime)

    {

        GraphicsDevice.Clear(Color.SeaShell);

        Vector2 s = // ScreenSize

        new Vector2( graphics.GraphicsDevice.Viewport.Width,

                     graphics.GraphicsDevice.Viewport.Height);

        // ** 2DLINE ** 2DLINE ** 2DLINE ** 2DLINE ** 2DLINE ** 2DLINE ** 2DLINE ** 2DLINE

        // ** 2DLINE ** 2DLINE ** 2DLINE ** 2DLINE ** 2DLINE ** 2DLINE ** 2DLINE ** 2DLINE

        DrawLine2D( new Vector2(0,0), new Vector2(s.X,s.Y), Color.Red);

        DrawLine2D( new Vector2(s.X,0), new Vector2(0,s.Y), Color.Blue);

        base.Draw(gameTime);

    }

}

// Program Entry Point

static class Program

{

    static void Main(string[] args)

    {

        using (GameClass game = new GameClass())

        {

            game.Run();

        }

    }

}