Victor

using System;
using System.Collections.Generic;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Audio;
using Microsoft.Xna.Framework.Content;
using Microsoft.Xna.Framework.GamerServices;
using Microsoft.Xna.Framework.Graphics;
using Microsoft.Xna.Framework.Input;
using Microsoft.Xna.Framework.Net;
using Microsoft.Xna.Framework.Storage;

using FlatRedBall;
using FlatRedBall.Content.AnimationChain;

using FlatRedBall.Gui;

using FlatRedBall.Graphics.Animation;
using FlatRedBall.Input;
using FlatRedBall.Math.Geometry;

namespace FlatRedBall_XNA_Template
{
    /// <summary>
    /// This is the main type for your game
    /// </summary>
    public class Game1 : Microsoft.Xna.Framework.Game
    {
        GraphicsDeviceManager graphics;

        SpriteList sprites;

        public Game1()
        {
            graphics = new GraphicsDeviceManager(this);
            Content.RootDirectory = "Content";
        }

        /// <summary>
        /// Allows the game to perform any initialization it needs to before starting to run.
        /// This is where it can query for any required services and load any non-graphic
        /// related content.  Calling base.Initialize will enumerate through any components
        /// and initialize them as well.
        /// </summary>
        protected override void Initialize()
        {
            FlatRedBallServices.InitializeFlatRedBall(this, this.graphics);

            // Uncomment the following line and add your Screen's fully qualified name
            // if using Screens in your project.  If not, or if you don't know what it means,
            // just ignore the following line for now.
            // For more information on Screens see the Screens wiki article on FlatRedBall.com.
            //Screens.ScreenManager.Start("FlatRedBall_XNA_Template1.Screens.SplashScreen");


            sprites = new SpriteList();

            SpriteManager.Camera.Z = 100;

            // Create 800 Sprites
            for (int i = 0; i < 800; i++)
            {
                Sprite redBall = SpriteManager.AddSprite("redball.bmp");
                SpriteManager.Camera.PositionRandomlyInView(redBall, 
                    SpriteManager.Camera.Z, SpriteManager.Camera.Z);
                float angle = (float)(FlatRedBallServices.Random.NextDouble() * 
                    Math.PI * 2);
                float magnitude = (float)FlatRedBallServices.Random.NextDouble() * 3;
                redBall.XVelocity = (float)Math.Cos(angle) * magnitude;
                redBall.YVelocity = (float)Math.Sin(angle) * magnitude;
                redBall.ColorOperation = FlatRedBall.Graphics.ColorOperation.Add;
                sprites.Add(redBall);
            }


            base.Initialize();
        }


        /// <summary>
        /// Allows the game to run logic such as updating the world,
        /// checking for collisions, gathering input, and playing audio.
        /// </summary>
        /// <param name="gameTime">Provides a snapshot of timing values.</param>
        protected override void Update(GameTime gameTime)
        {
            FlatRedBallServices.Update(gameTime);
            Screens.ScreenManager.Activity();

            // Sort all Sprites on the X axis
            sprites.SortXInsertionAscending(0, sprites.Count);

            float maximumXDistance = 2;
            float maximumDistanceSquared = 2*2;

            float furthestLeft = -SpriteManager.Camera.RelativeXEdgeAt(0) + 1;
            float furthestRight = SpriteManager.Camera.RelativeXEdgeAt(0) - 1;

            float furthestTop = SpriteManager.Camera.RelativeYEdgeAt(0) - 1;
            float furthestBottom = -SpriteManager.Camera.RelativeXEdgeAt(0) + 1;

            // reset all colors outside of the collision loop
            for (int i = 0; i < sprites.Count; i++)
            {
                sprites[i].Green = 0;

                // this could be partitioned too, but we're more concerned about the
                // collisions below

                if (sprites[i].X < furthestLeft && sprites[i].XVelocity < 0)
                {
                    sprites[i].X = furthestLeft;
                    sprites[i].XVelocity *= -1;
                }

                if (sprites[i].X > furthestRight && sprites[i].XVelocity > 0)
                {
                    sprites[i].X = furthestRight;
                    sprites[i].XVelocity *= -1;
                }

                if (sprites[i].Y > furthestTop && sprites[i].YVelocity > 0)
                {
                    sprites[i].Y = furthestTop;
                    sprites[i].YVelocity *= -1;
                }

                if (sprites[i].Y < furthestBottom && sprites[i].YVelocity < 0)
                {
                    sprites[i].Y = furthestBottom;
                    sprites[i].YVelocity *= -1;
                }
            }


            int j;
            float xDistance;
            float yDistance;
            for (int i = 0; i < sprites.Count - 1; i++)
            {
                for (j = i + 1; j < sprites.Count; j++)
                {
                    xDistance = sprites[j].Position.X - sprites[i].Position.X;
                    if (xDistance < maximumXDistance)
                    {
                        // The two are close enough on the X to perform collision, so check the
                        // distance between the two.
                        yDistance = sprites[j].Position.Y - sprites[i].Position.Y;

                        if (xDistance * xDistance + yDistance * yDistance <
                            maximumDistanceSquared)
                        {
                            sprites[i].Green = 1;
                            sprites[j].Green = 1;
                        }
                    }
                    else
                    {
                        // the two are too far away, so move on to the next Sprite
                        break;
                    }
                }
            }


            base.Update(gameTime);
        }

        /// <summary>
        /// This is called when the game should draw itself.
        /// </summary>
        /// <param name="gameTime">Provides a snapshot of timing values.</param>
        protected override void Draw(GameTime gameTime)
        {
            FlatRedBallServices.Draw();

            base.Draw(gameTime);
        }
    }
}