pong/Pong/Game1.cs

using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Graphics;
using Microsoft.Xna.Framework.Input;
using System;

//open content editor with mgcb-editor-windows

namespace Pong {
    public class Game1 : Game {
        private GraphicsDeviceManager _graphics;
        private SpriteBatch _spriteBatch;
        private Random random;
        private KeyboardState kState;

        public Texture2D ballTexture;
        public Texture2D playerOneTexture;
        public Texture2D playerTwoTexture;
        public Rectangle playerOne;
        public Rectangle playerTwo;
        
        Vector2 ballPosition;
        Vector2 playerOnePosition;
        Vector2 playerTwoPosition;
        Vector2 ballDir;
        
        float ballSpeed;
        float playerSpeed;

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

        protected override void Initialize() {
            // TODO: Add your initialization logic here
            Window.Title = "Pong";
            _graphics.PreferredBackBufferHeight = 720;
            _graphics.PreferredBackBufferWidth = 1280;
            _graphics.ApplyChanges();
            
            random = new Random();

            playerOneTexture = new Texture2D(_graphics.GraphicsDevice, 20, 125);
            playerTwoTexture = new Texture2D(_graphics.GraphicsDevice, 20, 125);

            //filling the player rectangles with color data
            Color[] data = new Color[playerOneTexture.Width*playerOneTexture.Height];
            for (int i = 0; i < data.Length; ++i) data[i] = Color.White;
            playerOneTexture.SetData(data);
            playerTwoTexture.SetData(data);

            ballPosition = new Vector2(_graphics.PreferredBackBufferWidth / 2, _graphics.PreferredBackBufferHeight / 2);
            ballDir = new Vector2(random.Next(-5, 5), random.Next(-7, 7));
            ballDir.X = ballDir.X < 0 ? -5 : 5;
            ballSpeed = 100.0f;
            playerSpeed = 500f;

            //players starting position
            playerOnePosition = new Vector2(25, _graphics.PreferredBackBufferHeight / 2 - playerOneTexture.Height / 2);
            playerTwoPosition = new Vector2(_graphics.PreferredBackBufferWidth - 50, _graphics.PreferredBackBufferHeight / 2 - playerTwoTexture.Height / 2);

            base.Initialize();
        }

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

            // TODO: use this.Content to load your game content here
            ballTexture = Content.Load<Texture2D>("Textures/ball");
        }

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

            kState = Keyboard.GetState();

            //Player one movement
            if (kState.IsKeyDown(Keys.W)) {
                playerOnePosition.Y -= playerSpeed * (float)gameTime.ElapsedGameTime.TotalSeconds;
                if(playerOnePosition.Y < 0) {
                    playerOnePosition.Y = 0;
                }
            }
            if (kState.IsKeyDown(Keys.S)) {
                playerOnePosition.Y += playerSpeed * (float)gameTime.ElapsedGameTime.TotalSeconds;
                if (playerOnePosition.Y + playerOneTexture.Height > _graphics.PreferredBackBufferHeight) {
                    playerOnePosition.Y = _graphics.PreferredBackBufferHeight - playerOneTexture.Height;
                }
            }

            //Player two movement
            if (kState.IsKeyDown(Keys.Up)) {
                playerTwoPosition.Y -= playerSpeed * (float)gameTime.ElapsedGameTime.TotalSeconds;
                if (playerTwoPosition.Y < 0) {
                    playerTwoPosition.Y = 0;
                }
            }
            if (kState.IsKeyDown(Keys.Down)) {
                playerTwoPosition.Y += playerSpeed * (float)gameTime.ElapsedGameTime.TotalSeconds;
                if (playerTwoPosition.Y + playerTwoTexture.Height > _graphics.PreferredBackBufferHeight) {
                    playerTwoPosition.Y = _graphics.PreferredBackBufferHeight - playerTwoTexture.Height;
                }
            }

            ballPosition.X += ballDir.X  * ballSpeed * (float)gameTime.ElapsedGameTime.TotalSeconds;
            ballPosition.Y += ballDir.Y  * ballSpeed * (float)gameTime.ElapsedGameTime.TotalSeconds;

            //Bouncing
            if (ballPosition.X > _graphics.PreferredBackBufferWidth - ballTexture.Width / 2) {
                ballDir.X = -ballDir.X; //_graphics.PreferredBackBufferWidth - ballTexture.Width / 2;
            } else if (ballPosition.X < ballTexture.Width / 2) {
                ballDir.X = -ballDir.X; //ballPosition.X = ballTexture.Width / 2;
            }

            if (ballPosition.Y > _graphics.PreferredBackBufferHeight - ballTexture.Height / 2) {
                ballDir.Y = -ballDir.Y; //ballPosition.Y = _graphics.PreferredBackBufferHeight - ballTexture.Height / 2;
            } else if (ballPosition.Y < ballTexture.Height / 2) {
                ballDir.Y = -ballDir.Y; //ballPosition.Y = ballTexture.Height / 2;
            }

            base.Update(gameTime);
        }

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

            // TODO: Add your drawing code here
            _spriteBatch.Begin();
            _spriteBatch.Draw(ballTexture, ballPosition, null, Color.White, 0f, new Vector2(ballTexture.Width / 2, ballTexture.Height / 2), Vector2.One, SpriteEffects.None, 0f);
            _spriteBatch.Draw(playerOneTexture, new Rectangle((int)playerOnePosition.X, (int)playerOnePosition.Y, playerOneTexture.Width, playerOneTexture.Height), Color.White);
            _spriteBatch.Draw(playerTwoTexture, new Rectangle((int)playerTwoPosition.X, (int)playerTwoPosition.Y, playerTwoTexture.Width, playerTwoTexture.Height), Color.White);
            _spriteBatch.End();           

            base.Draw(gameTime);
        }
    }
}