Bouncing balls in MonoGame

Ball.cs

namespace MonoGameCross_PlatformDesktopApplication1
{
    using Microsoft.Xna.Framework;
    using Microsoft.Xna.Framework.Graphics;
    using Microsoft.Xna.Framework.Input;

    public static class Program
    {
        [STAThread]
        private static void Main()
        {
            using var game = new Game1();
            game.Run();
        }
    }

    internal class Ball
    {
        public Vector2 Position = Vector2.Zero;
        public Texture2D? Texture;
        public Vector2 Velocity = Vector2.Zero;

        public void Reposition(float elapsedTotalSeconds)
        {
            Position.X += Velocity.X * elapsedTotalSeconds;
            Position.Y += Velocity.Y * elapsedTotalSeconds;
        }

        public void BounceInside(Rectangle bounds)
        {
            if (Texture is null) { return; }

            float o;

            if (Position.X < 0 && Velocity.X < 0)
            {
                Position.X *= -1;
                Velocity.X *= -1;
            }
            else if ((o = Position.X - (bounds.Width - Texture.Width)) > 0 && Velocity.X > 0)
            {
                Position.X -= o;
                Velocity.X *= -1;
            }

            if (Position.Y < 0 && Velocity.Y < 0)
            {
                Position.Y *= -1;
                Velocity.Y *= -1;
            }
            else if ((o = Position.Y - (bounds.Height - Texture.Width)) > 0 && Velocity.Y > 0)
            {
                Position.Y -= o;
                Velocity.Y *= -1;
            }
        }
    }

    public class Game1 : Game
    {
        private GraphicsDeviceManager _graphics;
        private SpriteBatch? _spriteBatch;

        private ICollection<Ball>? balls;

        public Game1()
        {
            _graphics = new(this);
            Content.RootDirectory = "Content";
            IsMouseVisible = true;
        }

        protected override void Initialize()
        {
            // TODO: Add your initialization logic here

            base.Initialize();
        }

        protected override void LoadContent()
        {
            _spriteBatch = new(GraphicsDevice);

            var random = Random.Shared;

            // TODO: use this.Content to load your game content here
            //var ballTexture = Content.Load<Texture2D>("ball");
            var ballList = new List<Ball>();
            for (var i = 0; i < 30; i++)
            {
                var texture = TextureFactory.CreateCircle(GraphicsDevice, random.Next(10, 40), random.Next(Colors.Values));
                ballList.Add(new()
                {
                    Texture = texture,
                    Velocity = new(random.Next(800), random.Next(800)),
                    Position = new(random.Next(GraphicsDevice.Viewport.Width - texture.Width), random.Next(GraphicsDevice.Viewport.Height - texture.Height)),
                });
            }
            balls = ballList;
        }

        protected override void Update(GameTime gameTime)
        {
            if (GamePad.GetState(PlayerIndex.One).Buttons.Back == ButtonState.Pressed || Keyboard.GetState().IsKeyDown(Keys.Escape))
            {
                Exit();
            }

            // TODO: Add your update logic here

            if (balls is not null)
            {
                foreach (var ball in balls)
                {
                    ball.Reposition((float)gameTime.ElapsedGameTime.TotalSeconds);
                    ball.BounceInside(_graphics.GraphicsDevice.Viewport.Bounds);
                }
            }

            base.Update(gameTime);
        }

        protected override void Draw(GameTime gameTime)
        {
            GraphicsDevice.Clear(Color.CornflowerBlue);

            // TODO: Add your drawing code here
            if (_spriteBatch is not null)
            {
                _spriteBatch.Begin();
                if (balls is not null)
                {
                    foreach (var ball in balls)
                    {
                        _spriteBatch.Draw(ball.Texture, ball.Position, Color.White);
                    }
                }
                _spriteBatch.End();
            }

            base.Draw(gameTime);
        }
    }

    public static class TextureFactory
    {
        public static Texture2D CreateCircle(GraphicsDevice graphicsDevice, int radius, Color color)
        {
            var diameter = radius * 2;
            var texture = new Texture2D(graphicsDevice, diameter, diameter);
            texture.SetData(CreateCircleData(radius, color));
            return texture;
        }

        private static Color[] CreateCircleData(int radius, Color color)
        {
            var diameter = radius * 2;
            var radiusSquared = radius * radius;

            var colorData = new Color[diameter * diameter];
            for (var x = 0; x < diameter; x++)
            {
                for (var y = 0; y < diameter; y++)
                {
                    var index = x * diameter + y;
                    var pos = new Vector2(x - radius, y - radius);
                    colorData[index] = pos.LengthSquared() <= radiusSquared ? color : Color.Transparent;
                }
            }
            return colorData;
        }
    }

    public static class RandomExn
    {
        public static T Next<T>(this Random random, IList<T> values) => values[random.Next(values.Count)];
    }

    public static class Colors
    {
        public static readonly Color[] Values =
        {
            Color.Transparent,
            Color.AliceBlue,
            Color.AntiqueWhite,
            Color.Aqua,
            Color.Aquamarine,
            Color.Azure,
            Color.Beige,
            Color.Bisque,
            Color.Black,
            Color.BlanchedAlmond,
            Color.Blue,
            Color.BlueViolet,
            Color.Brown,
            Color.BurlyWood,
            Color.CadetBlue,
            Color.Chartreuse,
            Color.Chocolate,
            Color.Coral,
            Color.CornflowerBlue,
            Color.Cornsilk,
            Color.Crimson,
            Color.Cyan,
            Color.DarkBlue,
            Color.DarkCyan,
            Color.DarkGoldenrod,
            Color.DarkGray,
            Color.DarkGreen,
            Color.DarkKhaki,
            Color.DarkMagenta,
            Color.DarkOliveGreen,
            Color.DarkOrange,
            Color.DarkOrchid,
            Color.DarkRed,
            Color.DarkSalmon,
            Color.DarkSeaGreen,
            Color.DarkSlateBlue,
            Color.DarkSlateGray,
            Color.DarkTurquoise,
            Color.DarkViolet,
            Color.DeepPink,
            Color.DeepSkyBlue,
            Color.DimGray,
            Color.DodgerBlue,
            Color.Firebrick,
            Color.FloralWhite,
            Color.ForestGreen,
            Color.Fuchsia,
            Color.Gainsboro,
            Color.GhostWhite,
            Color.Gold,
            Color.Goldenrod,
            Color.Gray,
            Color.Green,
            Color.GreenYellow,
            Color.Honeydew,
            Color.HotPink,
            Color.IndianRed,
            Color.Indigo,
            Color.Ivory,
            Color.Khaki,
            Color.Lavender,
            Color.LavenderBlush,
            Color.LawnGreen,
            Color.LemonChiffon,
            Color.LightBlue,
            Color.LightCoral,
            Color.LightCyan,
            Color.LightGoldenrodYellow,
            Color.LightGray,
            Color.LightGreen,
            Color.LightPink,
            Color.LightSalmon,
            Color.LightSeaGreen,
            Color.LightSkyBlue,
            Color.LightSlateGray,
            Color.LightSteelBlue,
            Color.LightYellow,
            Color.Lime,
            Color.LimeGreen,
            Color.Linen,
            Color.Magenta,
            Color.Maroon,
            Color.MediumAquamarine,
            Color.MediumBlue,
            Color.MediumOrchid,
            Color.MediumPurple,
            Color.MediumSeaGreen,
            Color.MediumSlateBlue,
            Color.MediumSpringGreen,
            Color.MediumTurquoise,
            Color.MediumVioletRed,
            Color.MidnightBlue,
            Color.MintCream,
            Color.MistyRose,
            Color.Moccasin,
            Color.MonoGameOrange,
            Color.NavajoWhite,
            Color.Navy,
            Color.OldLace,
            Color.Olive,
            Color.OliveDrab,
            Color.Orange,
            Color.OrangeRed,
            Color.Orchid,
            Color.PaleGoldenrod,
            Color.PaleGreen,
            Color.PaleTurquoise,
            Color.PaleVioletRed,
            Color.PapayaWhip,
            Color.PeachPuff,
            Color.Peru,
            Color.Pink,
            Color.Plum,
            Color.PowderBlue,
            Color.Purple,
            Color.Red,
            Color.RosyBrown,
            Color.RoyalBlue,
            Color.SaddleBrown,
            Color.Salmon,
            Color.SandyBrown,
            Color.SeaGreen,
            Color.SeaShell,
            Color.Sienna,
            Color.Silver,
            Color.SkyBlue,
            Color.SlateBlue,
            Color.SlateGray,
            Color.Snow,
            Color.SpringGreen,
            Color.SteelBlue,
            Color.Tan,
            Color.Teal,
            Color.Thistle,
            Color.Tomato,
            Color.Turquoise,
            Color.Violet,
            Color.Wheat,
            Color.White,
            Color.WhiteSmoke,
            Color.Yellow,
            Color.YellowGreen,
        };
    }
}