Thread: XNA code error Value cannot be null.

if (animations.ContainsKey(currentAnimation))

But it stopped working when I had tried to draw a list

Originally Posted by itsme86

You're going to have to give a little more context. It looks like animations is a dictionary, but that's not really enough information to know what you need.

Code:

 class GameObj
    {
        #region Declarations
        public Vector2 worldLocation;
        protected Vector2 velocity;
        protected bool flipped = false;
        protected float drawDepth = 0.85f;
        protected int FrameWidth;
        protected int FrameHeight;
        protected Dictionary<string, AnimationStrip> animations =
        new Dictionary<string, AnimationStrip>();
        protected string currentAnimation;
        protected Rectangle CollisionRectangle;
        private int Minlocxobj;
        private int Minlocyobj;
        private int Maxlocxobj;
        private int Maxlocyobj;
        
        public float health;

        #endregion
        public float timer;
     
        public int minlocxobj {

            get { return Minlocxobj; }
            set { Minlocxobj = value; }
        }


        public int minlocyobj
        {

            get { return Minlocyobj; }
            set { Minlocyobj = value; }
        }
        
        public int maxlocxobj
        {

            get { return Maxlocxobj; }
            set { Maxlocxobj = value; }
        }

        public int maxlocyobj
        {

            get { return Maxlocyobj; }
            set { Maxlocyobj = value; }
        }
        
        
        public Vector2 WorldLocation
        {
            get { return worldLocation; }
            set { worldLocation = value; }
        }

        public int frameWidth
        {
            get { return FrameWidth; }
            set { FrameWidth = value; }
        }

        public int frameHeight
        {
            get { return FrameHeight; }
            set { FrameHeight = value; }
        }

        public Rectangle objRectangle
        {
            get
            {
                return new Rectangle(
                  (int)worldLocation.X,
                  (int)worldLocation.Y,
                  FrameWidth,
                  FrameHeight);
            }
        }
        public Rectangle collisionRectangle
        {
            get
            {
                return new Rectangle(
                    (int)worldLocation.X + CollisionRectangle.X,
                    (int)objRectangle.Y + CollisionRectangle.Y,
                    CollisionRectangle.Width,
                    CollisionRectangle.Height);
            }
            set { CollisionRectangle = value; }
        }

 

        private void updateAnimation(GameTime gametime)
        {
           
              timer = (float)gametime.ElapsedGameTime.TotalSeconds;
            if (animations.ContainsKey(currentAnimation))
            {
                if (animations[currentAnimation].FinishedPlaying)
                {
                    PlayAnimation(animations[currentAnimation].NextAnimation);
                }
                else
                {
                    animations[currentAnimation].Update(gametime);
                }
            }
       
        
        
        }

        public void PlayAnimation(string name)
        {
            if (!(name == null) && animations.ContainsKey(name))
            {
                currentAnimation = name;
                animations[name].Play();
            }
        }


        public virtual void Update(GameTime gameTime)
        {

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

            
            updateAnimation(gameTime);
            Vector2 moveamount = velocity * elapsed;
            Vector2 newposition = WorldLocation + moveamount;



            /* newposition = new Vector2(
                MathHelper.Clamp(newposition.X, 0,
                  Camera.WorldRectangle.Width - frameWidth),
                MathHelper.Clamp(newposition.Y,2 * 5,
                  Camera.WorldRectangle.Height - frameHeight));*/
            WorldLocation = newposition;


        }
        public virtual void Draw(SpriteBatch spriteBatch)
        {
            if (animations.ContainsKey(currentAnimation))
            {
                SpriteEffects effect = SpriteEffects.None;

                if (flipped)
                {
                    effect = SpriteEffects.FlipHorizontally;
                }
                spriteBatch.Draw(
                    animations[currentAnimation].Texture,
                   Camera.WorldToScreen(objRectangle),
                    animations[currentAnimation].FrameRectangle,
                    Color.DeepSkyBlue, 0.0f, Vector2.Zero, effect, drawDepth);


            }
        }


    }
}

Which flows into my shrimp class

Code:

 class Shrimp : GameObj
    {
        public float damage = 0.0f;
        private float moveScale = 110.5f;
        public Vector2 targetplayer;
       
        
        public Shrimp(ContentManager content)
        {
            animations.Add("walk",
                new AnimationStrip(
                    content.Load<Texture2D>(@"shrimp\shrimpwalk"),
                    110,
                    "walk"));
            animations["walk"].LoopAnimation = true;

            animations.Add("death",
                new AnimationStrip(
                    content.Load<Texture2D>(@"shrimp\shrimp_death"),
                    110,
                    "death"));
            animations["death"].LoopAnimation = false;

            animations.Add("attack2",
                new AnimationStrip(
                    content.Load<Texture2D>(@"shrimp\shrimp_attack2"),
                    90,
                    "attack2"));
            animations["attack2"].LoopAnimation = true;
            animations["attack2"].FrameLength = .1005f;
        }

        public override void Update(GameTime gameTime)
      
      
        
        
        {

            Console.WriteLine("Fish", worldLocation);
            
            collisionRectangle = new Rectangle (100,150,150,150);

            
            health = 10;
            frameHeight = 50;
            frameWidth = 50;





            string newAnimation = "walk";

            damage = 20;
            velocity = new Vector2(0, 0);

            if (newAnimation == "attack2")
            {

                damage = -20;

            }
            if (Vector2.Distance(targetplayer, worldLocation) <= 100)
            {

                newAnimation = "walk";

                if (Vector2.Distance(targetplayer, worldLocation) <= 50)
                {
                    Console.WriteLine(timer);
                    newAnimation = "attack2";
                   //worldLocation.X = targetplayer.X + 50 ;
                }
                if (worldLocation.X < targetplayer.X)
                {

                    velocity = new Vector2(moveScale, velocity.Y);
                    flipped = false;
                    if (worldLocation.Y < targetplayer.Y)
                    {
                        velocity = new Vector2(velocity.X,moveScale);
                    
                    }
                }

                if (worldLocation.X > targetplayer.X)
                {

                    velocity = new Vector2(-moveScale, velocity.Y);
                    flipped = true;
                    if (worldLocation.Y > targetplayer.Y)
                    {
                        velocity = new Vector2(velocity.X, -moveScale);

                    }
                }
            
            }

            
            
            
            
            
            if (newAnimation != currentAnimation)
            {
                PlayAnimation(newAnimation);
            }

            base.Update(gameTime);
        }

    }
}

I then have it go into my levelmanger class as a list but its not drawing it

Code:

class LevelManager
    {
        private static ContentManager Content;
        private static OcTwo octwo;
        private static List<Shrimp> shrimps = new List<Shrimp>();
        private static Plant plant;
        
        private static lvl1 lvlone;
        public static void Initialize(

            ContentManager content,
            OcTwo gameoctwo, lvl1 lvl1game)
        {
            Content = content;
            octwo = gameoctwo;
            lvlone = lvl1game;

        }
        public static void loadme() {
            foreach (Shrimp shrimp in shrimps)
            {
                shrimp.targetplayer = octwo.worldLocation;
                shrimp.worldLocation = new Vector2(1000, 300);
            }
        
        }
        public static void Update(GameTime gameTime)
        {
            for (int x = 0; x <= 4; x++)
            {

                shrimps.Add(new Shrimp(Content));
            }


        }




          public static void Draw(SpriteBatch spriteBatch)
        {
            foreach (Shrimp shrimp in shrimps)
                shrimp.Draw(spriteBatch);
          
          }
        }

    }

And what it loads into for good measure

Code:

 public class Game1 : Microsoft.Xna.Framework.Game
    {
        GraphicsDeviceManager graphics;
        SpriteBatch spriteBatch;
        OcTwo octwo;
        lvl1 lvlone;
        SoundEffect soundEffect;
        Texture2D titleScreen;
        enum GameState { Starting, Playing };
        GameState gameState = GameState.Starting;
        
        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()
        {
            // TODO: Add your initialization logic here
            this.graphics.PreferredBackBufferWidth = 800;
            this.graphics.PreferredBackBufferHeight = 600;
            this.graphics.ApplyChanges();
            base.Initialize();
        }

        /// <summary>
        /// LoadContent will be called once per game and is the place to load
        /// all of your content.
        /// </summary>
        protected override void LoadContent()
        {
            // Create a new SpriteBatch, which can be used to draw textures.
            spriteBatch = new SpriteBatch(GraphicsDevice);
            Camera.WorldRectangle = new Rectangle(100, 200, 160 * 48, 12 * 48);
            Camera.Position = Vector2.Zero;
            Camera.ViewPortWidth = 800;
            Camera.ViewPortHeight = 600;
            titleScreen = Content.Load<Texture2D>(@"Textures\Uwk");

            soundEffect = Content.Load<SoundEffect>(@"Sounds\intro");
            
            octwo = new OcTwo(Content);
            lvlone = new lvl1(Content);
            LevelManager.Initialize(Content, octwo,  lvlone);
            // TODO: use this.Content to load your game content here
        }
        private void StartNewGame()
        {
            LevelManager.loadme();
            octwo.worldLocation = new Vector2(338, 492);
        }
        
        /// <summary>
        /// UnloadContent will be called once per game and is the place to unload
        /// all content.
        /// </summary>
        protected override void UnloadContent()
        {
            // TODO: Unload any non ContentManager content here
        }

        /// <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)
        {
            // Allows the game to exit
            if (GamePad.GetState(PlayerIndex.One).Buttons.Back == ButtonState.Pressed)
                this.Exit();

            KeyboardState keyState = Keyboard.GetState();
            if (gameState == GameState.Starting)
            {
                soundEffect.Play();

                if (keyState.IsKeyDown(Keys.Space))
                {
                    StartNewGame();
                    gameState = GameState.Playing;
                    LevelManager.Update(gameTime);
                }
            }
            if (gameState == GameState.Playing)
            {
                octwo.Update(gameTime);
                lvlone.Update(gameTime);
                LevelManager.Update(gameTime);

                soundEffect.Dispose();
                // TODO: Add your update logic here

             
            }
            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)
        {
            GraphicsDevice.Clear(Color.CornflowerBlue);

            // TODO: Add your drawing code here
            spriteBatch.Begin();
            GraphicsDevice.Clear(Color.Aquamarine);
            if (gameState == GameState.Starting)
            {


                spriteBatch.Draw(titleScreen, Vector2.Zero, Color.Wheat);
            }
            if (gameState == GameState.Playing)
            {
                lvlone.Draw(spriteBatch);
                LevelManager.Draw(spriteBatch);
                octwo.Draw(spriteBatch);
                


            }


            spriteBatch.End();
            base.Draw(gameTime);
        }
    }
}