脱線、ジジイは喜ぶクイックス

■残像をつくっていたら、ついムラムラしてきて作ってしまいました、ただ、近くにいた21歳プログラマーに「クリックすって知ってる？」と聞いたら知らないという返事が返って。ちょっとションボリです。
■ソース

namespace WindowsGame
{
    public class Game1 : Microsoft.Xna.Framework.Game
    {
        GraphicsDeviceManager graphics;
        ContentManager content;
        const int VERTICES_SIZE = 2;
        VertexPositionColor[] vertices = new VertexPositionColor[VERTICES_SIZE];
        VertexDeclaration vdecl;
        BasicEffect basicEffect;
        const int BOX_SIZE = 4;
        VertexPositionColor[] verticesBox = new VertexPositionColor[BOX_SIZE];
        const int lineCount = 10;
        Vector2[] pos = new Vector2[ lineCount * 2 ];
        Vector2[] direction= new Vector2[ lineCount * 2];

        public Game1()
        {
            graphics = new GraphicsDeviceManager(this);
            content = new ContentManager(Services);
        }

        protected override void Initialize()
        {
            vdecl = new VertexDeclaration(graphics.GraphicsDevice, VertexPositionColor.VertexElements);

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

            basicEffect.World = Matrix.Identity;
            basicEffect.View = Matrix.Identity;
            //原点（ 0, 0 ）を画面右上に設定
            basicEffect.Projection = Matrix.CreateOrthographicOffCenter(
                0.0f,                            // 左座標
                this.Window.ClientBounds.Width,  // 右座標　Window幅
                this.Window.ClientBounds.Height, // 下座標　Window高さ
                0.0f,　　　　　　　　　　　　　　// 上座標
                0.0f,                            // ニアクリップの距離
                1.0f);                           // ファークリップの距離
            Random ran = new Random();
            float ang;
            for (int i = 0; i < lineCount * 2; i++)
            {
                pos[ i ] = new Vector2((float)ran.Next(700), (float)ran.Next(500));
                ang= (float)ran.Next(360) * 3.14159f / 180.0f;
                direction[ i ] = new Vector2((float)Math.Sin(ang) * 8.0f, (float)Math.Cos(ang) * 8.0f);
            }

            base.Initialize();
        }

        protected override void Update(GameTime gameTime)
        {
            for (int i = 0; i < lineCount * 2; i++)
            {
                pos[i] += direction[i];
                if ((pos[i].X < 0) || (pos[i].X > 800 - 32))
                    direction[i].X = -direction[i].X;
                if ((pos[i].Y < 0) || (pos[i].Y > 600 - 32))
                    direction[i].Y = -direction[i].Y;
            }
             base.Update(gameTime);
        }

        protected override void Draw(GameTime gameTime)
        {
            basicEffect.VertexColorEnabled = true;
            //---------------------------------------------------------------------
            graphics.GraphicsDevice.RenderState.AlphaBlendEnable = true;
            graphics.GraphicsDevice.RenderState.SourceBlend = Blend.SourceAlpha;
            graphics.GraphicsDevice.RenderState.DestinationBlend = Blend.InverseSourceAlpha;
            Box(0, 0, 800, 600, new Color(0, 0, 0, 4));
            //---------------------------------------------------------------------
            graphics.GraphicsDevice.RenderState.AlphaBlendEnable = false;
            Color lineColor = new Color(128, 255, 80, 255);
            for (int i = 0; i < lineCount; i++)
                Line(pos[i * 2], pos[i * 2 + 1], lineColor);
            base.Draw(gameTime);
        }

        public void Line( Vector2 pos1, Vector2 pos2, Color lineColor)
        {
            vertices[0].Position.X = pos1.X;
            vertices[0].Position.Y = pos1.Y;
            vertices[0].Position.Z = 0;
            vertices[0].Color = lineColor;

            vertices[1].Position.X = pos2.X;
            vertices[1].Position.Y = pos2.Y;
            vertices[1].Position.Z = 0;
            vertices[1].Color = lineColor;

            basicEffect.Begin();
            graphics.GraphicsDevice.VertexDeclaration = vdecl;
            basicEffect.CurrentTechnique.Passes[0].Begin();
            graphics.GraphicsDevice.DrawUserPrimitives<VertexPositionColor>(
                PrimitiveType.LineList, vertices, 0, 1);
            basicEffect.CurrentTechnique.Passes[0].End();
            basicEffect.End();
        }

        public void Box(float x1, float y1, float x2, float y2, Color boxColor)
        {
            verticesBox[0].Position.X = x1;
            verticesBox[0].Position.Y = y1;
            verticesBox[0].Position.Z = 0;
            verticesBox[0].Color = boxColor;

            verticesBox[1].Position.X = x2;
            verticesBox[1].Position.Y = y1;
            verticesBox[1].Position.Z = 0;
            verticesBox[1].Color = boxColor;

            verticesBox[2].Position.X = x1;
            verticesBox[2].Position.Y = y2;
            verticesBox[2].Position.Z = 0;
            verticesBox[2].Color = boxColor;

            verticesBox[3].Position.X = x2;
            verticesBox[3].Position.Y = y2;
            verticesBox[3].Position.Z = 0;
            verticesBox[3].Color = boxColor;

            basicEffect.Begin();
            graphics.GraphicsDevice.VertexDeclaration = vdecl;
            basicEffect.CurrentTechnique.Passes[0].Begin();
            graphics.GraphicsDevice.DrawUserPrimitives<VertexPositionColor>(
                                PrimitiveType.TriangleStrip, verticesBox, 0, 2);
            basicEffect.CurrentTechnique.Passes[0].End();
            basicEffect.End();
        }
    }
}

■結果