手把手教用XNA开发winphone7游戏(五)大结局

 Alien Game逻辑

在这最有一个部分你将创建game-specific logic helper方法和类。胜利就在眼前,你的第一个winphone7程序就要出现了,加油加油!!(感谢http://winphone.us/)。另外最近imagecup要开始了,帮小美女推一下,学生们有时间都去参加。为了帮大家了解imagecup和winphone7的开发,我可能会针对学生讲一些入门级webcast,有详细计划再通知大家。刚刚翻译了imagecup的winphone7的评判标准,觉得有一条很好玩,就是要让使用了你的程序的人想去买一部winphone,呵呵这个占20%,大家加油了。另外有人要源代码,我把最后成品的源代码放到下一篇“番外篇”了,大家感兴趣可以去下载。

1.       GameplayScreen.cs 文件里,创建一个新的helper (GameplayScreen类之外)根据下面的代码:

(Code Snippet – Game Development with XNA – Gameplay Screen – Bullet class)

C#

/// <summary>

/// Represents either an alien or player bullet

/// </summary>

public class Bullet

{

   public Vector2 Position;

   public Vector2 Velocity;

   public bool IsAlive;

}

 

2.       Bullet 类后面添加两个helper:

(Code Snippet – Game Development with XNA – Gameplay Screen – Player and Alien classes)

C#

/// <summary>

/// The player's state

/// </summary>

public class Player

{

   public Vector2 Position;

   public Vector2 Velocity;

   public float Width;

   public float Height;

   public bool IsAlive;

   public float FireTimer;

   public float RespawnTimer;

   public string Name;

   public Texture2D Picture;

   public int Score;

   public int Lives;

}

 

/// <summary>

/// Data for an alien. The only difference between the ships

/// and the badguys are the texture used.

/// </summary>

public class Alien

{

   public Vector2 Position;

   public Texture2D Texture;

   public Vector2 Velocity;

   public float Width;

   public float Height;

   public int Score;

   public bool IsAlive;

   public float FireTimer;

   public float Accuracy;

   public int FireCount;

}

 

3.       添加如下GameplayScreen类的变量:

(Code Snippet – Game Development with XNA – Gameplay Screen – even more variables)

C#

Player player;

List<Alien> aliens;

List<Bullet> alienBullets;

List<Bullet> playerBullets;

 

4.       在构造函数中初始化这些变量,如下所示:

(Code Snippet – Game Development with XNA – Gameplay Screen – Player and Alien Initialization)

C#

public GameplayScreen()

{

    ...

 

    player = new Player();

    playerBullets = new List<Bullet>();

 

    aliens = new List<Alien>();

    alienBullets = new List<Bullet>();

 

    Accelerometer = new Accelerometer();

    if (AccelerometerSensor.Default.State == SensorState.Ready)

    {

        ...

    }

    ...

}

 

5.       初始化player变量Width HeightLoadContent 方法中 (初始化ParticleSystem之后):

(Code Snippet – Game Development with XNA – Gameplay Screen – Player Initialization in LoadContent method)

C#

public override void LoadContent()

{

    ...

 

    particles = new ParticleSystem(ScreenManager.Game.Content, ScreenManager.SpriteBatch);

    player.Width = tankTexture.Width;

    player.Height = tankTexture.Height;

 

    base.LoadContent();

}

 

6.       下面的一小段代码将添加游戏的逻辑。他们将根据用户的输入来改变“player1”的移动。导航到 HandleInput 的方法,并找到以下行:

C#

//TODO: Update player Velocity over X axis #1

 

在它的后面添加如下代码段:

(Code Snippet – Game Development with XNA – Gameplay Screen – Player Movements 1 in HandleInput method)

C#

player.Velocity.X = movement;

 

7.       找到以下行 (HandleInput 方法中):

C#

//TODO: Update player velocity over X axis #2

 

在其后添加如下代码:

(Code Snippet – Game Development with XNA – Gameplay Screen – Player Movements 2 in HandleInput method)

C#

player.Velocity.X = -1.0f;

 

8.       找到以下行 (HandleInput 方法中):

C#

//TODO: Update player velocity over X axis #3

 

在其后添加如下代码:

(Code Snippet – Game Development with XNA – Gameplay Screen – Player Movements 3 in HandleInput method)

C#

player.Velocity.X = 1.0f;

 

9.       找到以下行 (HandleInput 方法中):

C#

//TODO: Update player velocity over X axis #4

 

在其后添加如下代码:

(Code Snippet – Game Development with XNA – Gameplay Screen – Player Movements 4 in HandleInput method)

C#

player.Velocity.X = MathHelper.Min(input.CurrentGamePadStates[0].ThumbSticks.Left.X * 2.0f, 1.0f);

 

10.   找到以下行:

C#

//TODO: Fire the bullet

 

更改"if"语句根据下面的代码片断::

(Code Snippet – Game Development with XNA – Gameplay Screen – HandleInput firing the bullet code)

C#

if (player.FireTimer <= 0.0f && player.IsAlive && !gameOver)

{

    Bullet bullet = CreatePlayerBullet();

    bullet.Position = new Vector2((int)(player.Position.X + player.Width / 2) - bulletTexture.Width / 2, player.Position.Y - 4);

    bullet.Velocity = new Vector2(0, -256.0f);

    player.FireTimer = 1.0f;

 

    particles.CreatePlayerFireSmoke(player);

    playerFired.Play();

}

else if (gameOver)

    finishCurrentGame();

 

11.   创建 GameplayScreen 类中的以下方法:

此方法将创建Bullet类的一个实例。 此实例使用在前面的代码段。

(Code Snippet – Game Development with XNA – Gameplay Screen – CreatePlayerBullet method)

C#

/// <summary>

/// Returns an instance of a usable player bullet. Prefers reusing an /// existing (dead)

/// bullet over creating a new instance.

/// </summary>

/// <returns>A bullet ready to place into the world.</returns>

Bullet CreatePlayerBullet()

{

   Bullet b = null;

 

   for (int i = 0; i < playerBullets.Count; ++i)

   {

      if (playerBullets[i].IsAlive == false)

      {

         b = playerBullets[i];

         break;

      }

   }

 

   if (b == null)

   {

      b = new Bullet();

      playerBullets.Add(b);

   }

 

   b.IsAlive = true;

 

   return b;

}

 

12.   更改Update方法。在"base.Update()"方法调用之前,添加下面的蓝色突出显示的代码段:

此块的代码实际上提供了游戏的逻辑 它移动玩家和调用该方法来更新异型和重新计算子弹的位置。

(Code Snippet – Game Development with XNA – Gameplay Screen – Update method)

C#

public override void Update(GameTime gameTime,

    bool otherScreenHasFocus, bool coveredByOtherScreen)

{

    float elapsed = (float)gameTime.ElapsedGameTime.TotalSeconds;

 

    if (IsActive)

    {

        // Move the player

        if (player.IsAlive == true)

        {

            player.Position += player.Velocity * 128.0f * elapsed;

            player.FireTimer -= elapsed;

 

            if (player.Position.X <= 0.0f)

                player.Position = new Vector2(0.0f, player.Position.Y);

 

            if (player.Position.X + player.Width >= worldBounds.Right)

                player.Position = new Vector2(worldBounds.Right - player.Width, player.Position.Y);

        }

 

        Respawn(elapsed);

 

        UpdateAliens(elapsed);

 

        UpdateBullets(elapsed);

 

        CheckHits();

 

        if (player.IsAlive && player.Velocity.LengthSquared() > 0.0f)

            particles.CreatePlayerDust(player);

 

        particles.Update(elapsed);

    }

 

    base.Update(gameTime, otherScreenHasFocus, coveredByOtherScreen);

}

 

13.   GameplayScreen 类中添加helper方法:

Note: 下面的代码段中添加大量的帮助器方法。 方法用途如下:

重生: 检查是否,玩家已经"死亡"但这场游戏还没有结束, 如果这,它完成等待 respawnTimer结束后创建一个新的玩家实例屏幕的中间。

UpdateBullets 检查和更新屏幕上的玩家和异形子弹的位置。

UpdateAliens 移动异形,并计算是否发射子弹和朝哪个方向。

CheckHits 检查所有的子弹和玩家/异形的碰撞。它还将处理游戏逻辑,当命中发生时,进行让死亡,加分或者结束游戏等。

 

(Code Snippet – Game Development with XNA – Gameplay Screen – Helper update methods)

C#

/// <summary>

/// Handles respawning the player if we are playing a game and the player is dead.

/// </summary>

/// <param name="elapsed">Time elapsed since Respawn was called last.</param>

void Respawn(float elapsed)

{

    if (gameOver)

        return;

 

    if (!player.IsAlive)

    {

        player.RespawnTimer -= elapsed;

        if (player.RespawnTimer <= 0.0f)

        {

            // See if there are any bullets close...

            int left = worldBounds.Width / 2 - tankTexture.Width / 2 - 8;

            int right = worldBounds.Width / 2 + tankTexture.Width / 2 + 8;

 

            for (int i = 0; i < alienBullets.Count; ++i)

            {

                if (alienBullets[i].IsAlive == false)

                    continue;

 

                if (alienBullets[i].Position.X >= left || alienBullets[i].Position.X <= right)

                    return;

            }

 

            player.IsAlive = true;

            player.Position = new Vector2(worldBounds.Width / 2 - player.Width / 2, worldBounds.Bottom - groundTexture.Height + 2 - player.Height);

            player.Velocity = Vector2.Zero;

            player.Lives--;

        }

    }

}

 

/// <summary>

/// Moves all of the bullets (player and alien) and prunes "dead" bullets.

/// </summary>

/// <param name="elapsed"></param>

void UpdateBullets(float elapsed)

{

    for (int i = 0; i < playerBullets.Count; ++i)

    {

        if (playerBullets[i].IsAlive == false)

            continue;

 

        playerBullets[i].Position += playerBullets[i].Velocity * elapsed;

 

        if (playerBullets[i].Position.Y < -32)

        {

            playerBullets[i].IsAlive = false;

            hitStreak = 0;

        }

    }

 

    for (int i = 0; i < alienBullets.Count; ++i)

    {

        if (alienBullets[i].IsAlive == false)

            continue;

 

        alienBullets[i].Position += alienBullets[i].Velocity * elapsed;

 

        if (alienBullets[i].Position.Y > worldBounds.Height - groundTexture.Height - laserTexture.Height)

            alienBullets[i].IsAlive = false;

    }

}

 

/// <summary>

/// Moves the aliens and performs their "thinking" by determining if they

/// should shoot and where.

/// </summary>

/// <param name="elapsed">The elapsed time since UpdateAliens was called last.</param>

private void UpdateAliens(float elapsed)

{

    // See if it's time to spawn an alien;

    alienSpawnTimer -= elapsed;

    if (alienSpawnTimer <= 0.0f)

    {

        SpawnAlien();

        alienSpawnTimer += alienSpawnRate;

    }

 

    for (int i = 0; i < aliens.Count; ++i)

    {

        if (aliens[i].IsAlive == false)

            continue;

 

        aliens[i].Position += aliens[i].Velocity * elapsed;

        if ((aliens[i].Position.X < -aliens[i].Width - 64 && aliens[i].Velocity.X < 0.0f) ||

            (aliens[i].Position.X > worldBounds.Width + 64 && aliens[i].Velocity.X > 0.0f))

        {

            aliens[i].IsAlive = false;

            continue;

        }

 

        aliens[i].FireTimer -= elapsed;

 

        if (aliens[i].FireTimer <= 0.0f && aliens[i].FireCount > 0)

        {

            if (player.IsAlive)

            {

                Bullet bullet = CreateAlienBullet();

                bullet.Position.X = aliens[i].Position.X + aliens[i].Width / 2 - laserTexture.Width / 2;

                bullet.Position.Y = aliens[i].Position.Y + aliens[i].Height;

                if ((float)random.NextDouble() <= aliens[i].Accuracy)

                {

                    bullet.Velocity = Vector2.Normalize(player.Position - aliens[i].Position) * 64.0f;

                }

                else

                {

                    bullet.Velocity = new Vector2(-8.0f + 16.0f * (float)random.NextDouble(), 64.0f);

                }

 

                alienFired.Play();

            }

 

            aliens[i].FireCount--;

        }

    }

}

 

/// <summary>

/// Performs all bullet and player/alien collision detection. Also handles game logic

/// when a hit occurs, such as killing something, adding score, ending the game, etc.

/// </summary>

void CheckHits()

{

    if (gameOver)

        return;

 

    for (int i = 0; i < playerBullets.Count; ++i)

    {

        if (playerBullets[i].IsAlive == false)

            continue;

 

        for (int a = 0; a < aliens.Count; ++a)

        {

            if (aliens[a].IsAlive == false)

                continue;

 

            if ((playerBullets[i].Position.X >= aliens[a].Position.X && playerBullets[i].Position.X <= aliens[a].Position.X + aliens[a].Width) && (playerBullets[i].Position.Y >= aliens[a].Position.Y && playerBullets[i].Position.Y <= aliens[a].Position.Y + aliens[a].Height))

            {

                playerBullets[i].IsAlive = false;

                aliens[a].IsAlive = false;

 

                hitStreak++;

 

                player.Score += aliens[a].Score * (hitStreak / 5 + 1);

 

                if (player.Score > highScore)

                    highScore = player.Score;

 

                if (player.Score > nextLife)

                {

                    player.Lives++;

                    nextLife += nextLife;

                }

 

                levelKillCount--;

                if (levelKillCount <= 0)

                    AdvanceLevel();

 

                particles.CreateAlienExplosion(new Vector2(aliens[a].Position.X + aliens[a].Width / 2, aliens[a].Position.Y + aliens[a].Height / 2));

 

                alienDied.Play();

            }

        }

    }

 

    if (player.IsAlive == false)

        return;

 

    for (int i = 0; i < alienBullets.Count; ++i)

    {

        if (alienBullets[i].IsAlive == false)

            continue;

 

        if ((alienBullets[i].Position.X >= player.Position.X + 2 && alienBullets[i].Position.X <= player.Position.X + player.Width - 2) && (alienBullets[i].Position.Y >= player.Position.Y + 2 && alienBullets[i].Position.Y <= player.Position.Y + player.Height))

        {

            alienBullets[i].IsAlive = false;

 

            player.IsAlive = false;

 

            hitStreak = 0;

 

            player.RespawnTimer = 3.0f;

            particles.CreatePlayerExplosion(new Vector2(player.Position.X + player.Width / 2, player.Position.Y + player.Height / 2));

 

            playerDied.Play();

 

            if (player.Lives <= 0)

            {

                gameOver = true;

            }

        }

 

    }

}

 

/// <summary>

/// Advances the difficulty of the game one level.

/// </summary>

void AdvanceLevel()

{

    baseLevelKillCount += 5;

    levelKillCount = baseLevelKillCount;

    alienScore += 25;

    alienSpawnRate -= 0.3f;

    alienMaxAccuracy += 0.1f;

    if (alienMaxAccuracy > 0.75f)

        alienMaxAccuracy = 0.75f;

 

    alienSpeedMin *= 1.35f;

    alienSpeedMax *= 1.35f;

 

    if (alienSpawnRate < 0.33f)

        alienSpawnRate = 0.33f;

 

    if (transitionFactor == 1.0f)

    {

        transitionRate = -0.5f;

    }

    else

    {

        transitionRate = 0.5f;

    }

}

 

14.   GameplayScreen 类中添加如下代码:

Note: 下面的代码片断还增加了大量的帮助器方法。 他们的目的是,如下所示: CreateAlienBullet 创建的异形的子弹,将用于异形向玩家开火

SpawnAlien 初始化一个新的异形实例,设置了的初始位置、速度,选择颜色纹理等。

CreateAlien 创建新异形的实例,并将其添加到异形集合

 

(Code Snippet – Game Development with XNA – Gameplay Screen – Helper aliens methods)

C#

/// <summary>

/// Returns an instance of a usable alien bullet. Prefers reusing an existing (dead)

/// bullet over creating a new instance.

/// </summary>

/// <returns>A bullet ready to place into the world.</returns>

Bullet CreateAlienBullet()

{

    Bullet b = null;

 

    for (int i = 0; i < alienBullets.Count; ++i)

    {

        if (alienBullets[i].IsAlive == false)

        {

            b = alienBullets[i];

            break;

        }

    }

 

    if (b == null)

    {

        b = new Bullet();

        alienBullets.Add(b);

    }

 

    b.IsAlive = true;

 

    return b;

}

 

/// <summary>

/// Creates an instance of an alien, sets the initial state, and places it into the world.

/// </summary>

private void SpawnAlien()

{

    Alien newAlien = CreateAlien();

 

    if (random.Next(2) == 1)

    {

        newAlien.Position.X = -64.0f;

        newAlien.Velocity.X = random.Next((int)alienSpeedMin, (int)alienSpeedMax);

    }

    else

    {

        newAlien.Position.X = worldBounds.Width + 32;

        newAlien.Velocity.X = -random.Next((int)alienSpeedMin, (int)alienSpeedMax);

    }

 

    newAlien.Position.Y = 24.0f + 80.0f * (float)random.NextDouble();

 

    // Aliens

    if (transitionFactor > 0.0f)

    {

        switch (random.Next(4))

        {

            case 0:

                newAlien.Texture = badguy_blue;

                break;

            case 1:

                newAlien.Texture = badguy_red;

                break;

            case 2:

                newAlien.Texture = badguy_green;

                break;

            case 3:

                newAlien.Texture = badguy_orange;

               break;

        }

    }

    else

    {

        newAlien.Texture = alienTexture;

    }

 

    newAlien.Width = newAlien.Texture.Width;

    newAlien.Height = newAlien.Texture.Height;

    newAlien.IsAlive = true;

    newAlien.Score = alienScore;

 

    float duration = screenHeight / newAlien.Velocity.Length();

 

    newAlien.FireTimer = duration * (float)random.NextDouble();

    newAlien.FireCount = 1;

 

    newAlien.Accuracy = alienMaxAccuracy;

}

 

/// <summary>

/// Returns an instance of a usable alien instance. Prefers reusing an existing (dead)

/// alien over creating a new instance.

/// </summary>

/// <returns>An alien ready to place into the world.</returns>

Alien CreateAlien()

{

    Alien b = null;

 

    for (int i = 0; i < aliens.Count; ++i)

    {

        if (aliens[i].IsAlive == false)

        {

            b = aliens[i];

            break;

        }

    }

 

    if (b == null)

    {

        b = new Alien();

        aliens.Add(b);

    }

 

    b.IsAlive = true;

 

    return b;

}

 

15.   .导航到Draw方法并添加下面的蓝色突出显示的代码段,Screen.SpriteBatch.Begin() Screen.SpriteBatch.End() 之间:

这样更改方法方法将呼调用helper方法以在屏幕上绘制变化后的内容。

(Code Snippet – Game Development with XNA – Gameplay Screen – Draw method update)

C#

public override void Draw(GameTime gameTime)

{

    float elapsedTime = (float)gameTime.ElapsedGameTime.TotalSeconds;

 

    ScreenManager.SpriteBatch.Begin();

 

    DrawBackground(elapsedTime);

    DrawAliens();

    DrawPlayer();

    DrawBullets();

    particles.Draw();

    DrawForeground(elapsedTime);

    DrawHud();

 

    ScreenManager.SpriteBatch.End();

}

 

16.   Draw 方法后面添加如下方法:

Note: 下面的代码段中添加大量的绘图相关的Helper方法。 方法用途如下: DrawPlayer 绘制玩家的坦克。

DrawAliens 绘制所有异形

DrawBullets 绘制所有的子弹 (玩家的和异形的)。

DrawForeground 作为前台绘制云,并将其移动。

DrawBackground 绘制草、 丘陵、 山地和太阳/月亮。 此外处理白天和黑夜之间转换。

DrawHud 绘制分数、剩余的生命值和" GAME OVER "需要的时候。

drawString 绘制隐藏的文本的通用方法。

 

(Code Snippet – Game Development with XNA – Gameplay Screen – Draw methods)

C#

/// <summary>

/// Draws the player's tank

/// </summary>

void DrawPlayer()

{

   if (!gameOver && player.IsAlive)

   {

      ScreenManager.SpriteBatch.Draw(tankTexture,                player.Position, Color.White);

   }

}

 

/// <summary>

/// Draws all of the aliens.

/// </summary>

void DrawAliens()

{

   for (int i = 0; i < aliens.Count; ++i)

   {

      if (aliens[i].IsAlive)                                 ScreenManager.SpriteBatch.Draw(aliens[i].Texture,          new Rectangle((int)aliens[i].Position.X,                         (int)aliens[i].Position.Y,                          (int)aliens[i].Width,                             (int)aliens[i].Height),                             Color.White);

   }

}

 

/// <summary>

/// Draw both the player and alien bullets.

/// </summary>

private void DrawBullets()

{

   for (int i = 0; i < playerBullets.Count; ++i)

   {

      if (playerBullets[i].IsAlive)

         ScreenManager.SpriteBatch.Draw(bulletTexture,               playerBullets[i].Position, Color.White);

   }

 

   for (int i = 0; i < alienBullets.Count; ++i)

   {

      if (alienBullets[i].IsAlive)

         ScreenManager.SpriteBatch.Draw(laserTexture,                    alienBullets[i].Position, Color.White);

   }

}

 

/// <summary>

/// Draw the foreground, which is basically the clouds. I think I had planned on one point

/// having foreground grass that was drawn in front of the tank.

/// </summary>

/// <param name="elapsedTime">The elapsed time since last Draw</param>

private void DrawForeground(float elapsedTime)

{

   // Move the clouds. Movement seems like an Update thing to do, but this animations

   // have no impact over gameplay.

   cloud1Position += new Vector2(24.0f, 0.0f) * elapsedTime;

   if (cloud1Position.X > screenWidth)

      cloud1Position.X = -cloud1Texture.Width * 2.0f;

 

   cloud2Position += new Vector2(16.0f, 0.0f) * elapsedTime;

   if (cloud2Position.X > screenWidth)

      cloud2Position.X = -cloud1Texture.Width * 2.0f;

 

   ScreenManager.SpriteBatch.Draw(cloud1Texture,             cloud1Position, Color.White);

   ScreenManager.SpriteBatch.Draw(cloud2Texture,     cloud2Position, Color.White);

}

 

/// <summary>

/// Draw the grass, hills, mountains, and sun/moon. Handle transitioning

/// between day and night as well.

/// </summary>

/// <param name="elapsedTime">The elapsed time since last Draw</param>

private void DrawBackground(float elapsedTime)

{

   transitionFactor += transitionRate * elapsedTime;

   if (transitionFactor < 0.0f)

   {

      transitionFactor = 0.0f;

      transitionRate = 0.0f;

   }

   if (transitionFactor > 1.0f)

   {

      transitionFactor = 1.0f;

      transitionRate = 0.0f;

   }

 

   Vector3 day = Color.White.ToVector3();

   Vector3 night = new Color(80, 80, 180).ToVector3();

   Vector3 dayClear = Color.CornflowerBlue.ToVector3();

   Vector3 nightClear = night;

 

   Color clear = new Color(Vector3.Lerp(dayClear,                    nightClear, transitionFactor));

   Color tint = new Color(Vector3.Lerp(day, night,                   transitionFactor));

 

   // Clear the background, using the day/night color

   ScreenManager.Game.GraphicsDevice.Clear(clear);

 

   // Draw the mountains

   ScreenManager.SpriteBatch.Draw(mountainsTexture, new Vector2(0, screenHeight - mountainsTexture.Height),            tint);

 

   // Draw the hills

   ScreenManager.SpriteBatch.Draw(hillsTexture, new Vector2(0, screenHeight - hillsTexture.Height), tint);

 

   // Draw the ground

   ScreenManager.SpriteBatch.Draw(groundTexture, new     Vector2(0, screenHeight - groundTexture.Height),               tint);

 

   // Draw the sun or moon (based on time)

   ScreenManager.SpriteBatch.Draw(sunTexture, sunPosition,           new Color(255, 255, 255, (byte)(255.0f * (1.0f -                  transitionFactor))));

   ScreenManager.SpriteBatch.Draw(moonTexture, sunPosition,          new Color(255, 255, 255, (byte)(255.0f *                      transitionFactor)));

}

 

/// <summary>

/// Draw the hud, which consists of the score elements and the GAME OVER tag.

/// </summary>

void DrawHud()

{

   float scale = 2.0f;

 

   if (gameOver)

   {

      Vector2 size = menuFont.MeasureString("GAME OVER");

      DrawString(menuFont, "GAME OVER", new Vector2(ScreenManager.Game.GraphicsDevice.Viewport.Width / 2 - size.X, ScreenManager.Game.GraphicsDevice.Viewport.Height / 2 - size.Y / 2), new Color(255, 64, 64), scale);

 

   }

   else

   {

      int bonus = 100 * (hitStreak / 5);

      string bonusString = (bonus > 0 ? " (" + bonus.ToString(System.Globalization.CultureInfo.CurrentCulture) + "%)" : "");

      // Score

      DrawString(scoreFont, "SCORE: " + player.Score.ToString(System.Globalization.CultureInfo .CurrentCulture) + bonusString, new     Vector2(leftOffset, topOffset), Color.Yellow, scale);

 

     string text = "LIVES: " +  player.Lives.ToString(System.Globalization.CultureInfo .CurrentCulture);

     Vector2 size = scoreFont.MeasureString(text);

     size *= scale;

 

     // Lives

     DrawString(scoreFont, text, new Vector2(screenWidth -           leftOffset - (int)size.X, topOffset),                  Color.Yellow,  scale);

 

     DrawString(scoreFont, "LEVEL: " + (((baseLevelKillCount - 5) / 5) + 1).ToString(System.Globalization.CultureInfo.CurrentCulture), new Vector2(leftOffset, screenHeight - bottomOffset), Color.Yellow, scale);

 

     text = "HIGH SCORE: " +     highScore.ToString(System.Globalization.CultureInfo

.CurrentCulture);

 

     size = scoreFont.MeasureString(text);

 

     DrawString(scoreFont, text, new Vector2(screenWidth -           leftOffset - (int)size.X * 2, screenHeight -           bottomOffset), Color.Yellow, scale);

   }

}

 

/// <summary>

/// A simple helper to draw shadowed text.

/// </summary>

void DrawString(SpriteFont font, string text,

         Vector2 position, Color color)

{

   ScreenManager.SpriteBatch.DrawString(font, text, new Vector2(position.X + 1, position.Y + 1), Color.Black);

   ScreenManager.SpriteBatch.DrawString(font, text, position, color);

}

 

/// <summary>

/// A simple helper to draw shadowed text.

/// </summary>

void DrawString(SpriteFont font, string text,

Vector2 position, Color color, float fontScale)

{

   ScreenManager.SpriteBatch.DrawString(font, text, new Vector2(position.X + 1, position.Y + 1), Color.Black,     0, new Vector2(0, font.LineSpacing / 2), fontScale,     SpriteEffects.None, 0);

   ScreenManager.SpriteBatch.DrawString(font, text, position, color, 0, new Vector2(0, font.LineSpacing /  2), fontScale, SpriteEffects.None, 0);

}

 

 

17.   找到 LoadContent 方法,在base.LoadContent() 调用后面体检如下代码:

C#

public override void LoadContent()

{

    ...

    player.Width = tankTexture.Width;

    player.Height = tankTexture.Height;

 

    base.LoadContent();

 

    LoadHighscore();

    Start();

}

 

18.   找到 UnloadContent 方法并particles = null;之前的位置添加下面的代码:

C#

public override void UnloadContent()

{

    SaveHighscore();

 

    particles = null;

 

    base.UnloadContent();

}

 

19.   创建一个区域loading/unloading high scores logic。我们需要通过Isolated Storage来读取Windows Phone 文件系统中的数据。用如下代码在GameplayScreen类中创建logic:

(Code Snippet – Game Development with XNA – Gameplay Screen – Highscore storage methods)

C#

#region Highscore loading/saving logic

/// <summary>

/// Saves the current highscore to a text file. The StorageDevice was selected during screen loading.

/// </summary>

private void SaveHighscore()

{

    using (IsolatedStorageFile isf = IsolatedStorageFile.GetUserStoreForApplication())

    {

        using (IsolatedStorageFileStream isfs = new IsolatedStorageFileStream("highscores.txt", FileMode.Create, isf))

        {

            using (StreamWriter writer = new StreamWriter(isfs))

            {

                writer.Write(highScore.ToString(System.Globalization.CultureInfo.InvariantCulture));

                writer.Flush();

                writer.Close();

            }

        }

    }

}

 

/// <summary>

/// Loads the high score from a text file. The StorageDevice was selected during the loading screen.

/// </summary>

private void LoadHighscore()

{

    using (IsolatedStorageFile isf = IsolatedStorageFile.GetUserStoreForApplication())

    {

        if (isf.FileExists("highscores.txt"))

        {

            using (IsolatedStorageFileStream isfs = new IsolatedStorageFileStream("highscores.txt", FileMode.Open, isf))

            {

                using (StreamReader reader = new StreamReader(isfs))

                {

                    try

                    {

                        highScore = Int32.Parse(reader.ReadToEnd(), System.Globalization.CultureInfo.InvariantCulture);

                    }

                    catch (FormatException)

                    {

                        highScore = 10000;

                    }

                    finally

                    {

                        if (reader != null)

                            reader.Close();

                    }

                }

            }

        }

    }

}

#endregion

 

20.   GameplayScreen 类中创建Start方法来开始一个新游戏:

(Code Snippet – Game Development with XNA – Gameplay Screen – Start method)

C#

/// <summary>

/// Starts a new game session, setting all game states to initial values.

/// </summary>

void Start()

{

    if (gameOver)

    {

        player.Score = 0;

        player.Lives = 3;

        player.RespawnTimer = 0.0f;

 

        gameOver = false;

 

        aliens.Clear();

        alienBullets.Clear();

        playerBullets.Clear();

 

        Respawn(0.0f);

    }

 

    transitionRate = 0.0f;

    transitionFactor = 0.0f;

    levelKillCount = 5;

    baseLevelKillCount = 5;

    alienScore = 25;

    alienSpawnRate = 1.0f;

 

    alienMaxAccuracy = 0.25f;

 

    alienSpeedMin = 24.0f;

    alienSpeedMax = 32.0f;

 

    alienSpawnRate = 2.0f;

    alienSpawnTimer = alienSpawnRate;

 

    nextLife = 5000;

}

 

21.   打开 ParticleSystem.cs文件

22.   添加如下命名申明:

(Code Snippet – Game Development with XNA – ParticleSystem – using statement)

C#

using AlienGame;

 

23.   在这个步骤,你将添加两个方法。一个用来创建玩家控制坦克时泥土/灰尘的效果。一个用来创建玩家发射子弹时,火焰的效果。添加如下方法到ParticleSystem 类中:

(Code Snippet – Game Development with XNA – ParticleSystem – Helper player effects methods)

C#

/// <summary>

/// Creates the mud/dust effect when the player moves.

/// </summary>

/// <param name="position">Where on the screen to create the effect.</param>       

public void CreatePlayerDust(Player player)

{

    for (int i = 0; i < 2; ++i)

    {

        Particle p = CreateParticle();

        p.Texture = smoke;

        p.Color = new Color(125, 108, 43);

        p.Position.X = player.Position.X + player.Width * (float)random.NextDouble();

        p.Position.Y = player.Position.Y + player.Height - 3.0f * (float)random.NextDouble();

        p.Alpha = 1.0f;

        p.AlphaRate = -2.0f;

        p.Life = 0.5f;

        p.Rotation = 0.0f;

        p.RotationRate = -2.0f + 4.0f * (float)random.NextDouble();

        p.Scale = 0.25f;

        p.ScaleRate = 0.5f;

        p.Velocity.X = -4 + 8.0f * (float)random.NextDouble();

        p.Velocity.Y = -8 + 4.0f * (float)random.NextDouble();

    }

}

 

/// <summary>

/// Creates the effect for when the player fires a bullet.

/// </summary>

/// <param name="position">Where on the screen to create the effect.</param>       

public void CreatePlayerFireSmoke(Player player)

{

    for (int i = 0; i < 8; ++i)

    {

        Particle p = CreateParticle();

        p.Texture = smoke;

        p.Color = Color.White;

        p.Position.X = player.Position.X + player.Width / 2;

        p.Position.Y = player.Position.Y;

        p.Alpha = 1.0f;

        p.AlphaRate = -1.0f;

        p.Life = 1.0f;

        p.Rotation = 0.0f;

        p.RotationRate = -2.0f + 4.0f * (float)random.NextDouble();

        p.Scale = 0.25f;

        p.ScaleRate = 0.25f;

        p.Velocity.X = -4 + 8.0f * (float)random.NextDouble();

        p.Velocity.Y = -16.0f + -32.0f * (float)random.NextDouble();

    }

}

 

24.   编译并运行该应用程序。 选择"开始游戏"菜单项,并享受你自己编写的游戏吧。

Note: 在模拟器中我们使用桌面的键盘移动车辆,您需要首先按PAUSE /BREAK 键。 这将开启或者关闭仿真程序软件输入面板 (SIP) 或者桌面的键盘。因为键盘不能同时作为仿真程序软件输入面板 (SIP)和桌面的键盘,这个问题将在后面的版本里解决。

手把手教用XNA开发winphone7游戏(五)大结局

1

完工的游戏

恭喜你,你终于完成了一个属于你自己的winphone7手机程序。

在今天的部分的过程中,您创建包括玩家和异形的移动计算、 命中的检测、 屏幕绘制,和其他一些的 AlienGame 逻辑。

虽然这个游戏完成了,但是我想大家可能有更多的疑问和想改进的地方,那让我们进入

手把手教用XNA开发winphone7游戏中级教程

 

 

 

 

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