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What am I doing wrong in this Monogame class?

What am I doing wrong in this class? I'm using monogame and C# but my object won't render in the program.
class Player : Game
{
Texture2D PlayerSprite;
Vector2 PlayerPosition;
public Player()
{
Content.RootDirectory = "Content";
PlayerSprite = Content.Load<Texture2D>("spr_Player");
PlayerPosition = Vector2.Zero;
}
public void Update()
{
}
public void Draw(SpriteBatch SpriteBatch)
{
SpriteBatch.Begin();
SpriteBatch.Draw(PlayerSprite,PlayerPosition, new Rectangle(0, 0, 32,32), Color.White);
SpriteBatch.End();
}
}

The Load, Update, and Draw methods belong to the inherited Game class and are overrided by it.
You too need to start your SpriteBacth object.
GraphicsDevice object has exist in Game main class.
Try this:
class Player : Game
{
Texture2D PlayerSprite;
Vector2 PlayerPosition;
SpriteBatch spriteBatch;
public Player()
{
Content.RootDirectory = "Content";
PlayerSprite = Content.Load<Texture2D>("spr_Player");
PlayerPosition = Vector2.Zero;
}
protected override void LoadContent()
{
spriteBatch = new SpriteBatch(GraphicsDevice);
}
protected override void Update(GameTime gameTime)
{
}
protected override void Draw(GameTime gameTime)
{
spriteBatch.Begin();
spriteBatch.Draw(PlayerSprite,PlayerPosition, new Rectangle(0, 0, 32,32), Color.White);
spriteBatch.End();
}
}

C# XNA Add a GameComponent from within a GameComponent

public class Menu : DrawableGameComponent
{
ContentManager Content;
GraphicsDeviceManager graphics;
SpriteBatch spriteBatch;
Audio MenuMusic;
public Menu(Game game) : base(game)
{
spriteBatch = Game.Services.GetService(typeof(SpriteBatch)) as SpriteBatch;
graphics = Game.Services.GetService(typeof(GraphicsDeviceManager)) as GraphicsDeviceManager;
Content = game.Content;
Content.RootDirectory = #"Content\Menu\";
*MenuMusic = new Audio(game);* // Instantiate the new DrawableGameComponent
Game.Components.Add(this);
MenuMusic.PauseTune = false;
}
public override void Initialize()
{
Menustate = MenuState.LoadContent;
base.Initialize();
}
protected override void LoadContent()
{
base.LoadContent();
}
protected override void UnloadContent()
{
base.UnloadContent();
}
public override void Update(GameTime gameTime)
{
base.Update(gameTime);
}
public override void Draw(GameTime gameTime)
{
base.Draw(gameTime);
}
}
public class Audio : DrawableGameComponent
{
public bool PauseTune
{
get { return PauseTune; }
set { PauseTune = value; }
}
SoundEffect Tune = null;
SoundEffectInstance SFXInstance;
public Audio(Game game) : base(game)
{
*game.Components.Add(this)*;// This is the problem. It adds an entirely new Game object. :(
}
public override void Initialize()
{
PauseTune = true;
base.Initialize();
}
protected override void LoadContent()
{
switch (Game1.Gamestate)
{
case GameState.Menu:
string AudioPath = #"Audio\";
Tune = Game.Content.Load<SoundEffect>(AudioPath + "Tune");
break;
case GameState.InitialiseGame:
break;
case GameState.PlayGame:
break;
default:
break;
}
if (Tune != null) SFXInstance = Tune.CreateInstance();
base.LoadContent();
}
protected override void UnloadContent()
{
base.UnloadContent();
}
public override void Update(GameTime gameTime)
{
if (Tune != null)
{
if (PauseTune)
{
if (SFXInstance.State == SoundState.Playing)
SFXInstance.Pause();
}
else
{
if (SFXInstance.State != SoundState.Playing)
SFXInstance.Play();
}
}
base.Update(gameTime);
}
public override void Draw(GameTime gameTime)
{
base.Draw(gameTime);
}
}
The probelem comes when I use the Menu to add a new Audio class instance.
The Audio constructor attempts to add the new GameCompent but fails.
What it actually does is create an entirely new Game instance, which then goes on to instantiate a new Menu that attempts to add a new Audio class instance..... Until I eventually get a - would you beleive? - stackoverflow error.
What am I doing wrong? / How can I add one component from within another?

DOH! Some days I should never turn on my computer :)
Or better yet - after a long, tiring day do NOT mess with mycode.
A self-referencing PauseTune property.

Object reference not set to an instance of an object. What is wrong? [closed]

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Closed 10 years ago.
I have two classes: Game1 and Animation.
I always get that "Object reference not set to an instance of an object." error message in this line of the Game1 class: animation.Draw(spriteBatch);
What is wrong? I don't know what to change.
Animation class code:
public class Animation
{
private int _animIndex;
public TimeSpan PassedTime { get; private set; }
public Rectangle[] SourceRects { get; private set; }
public Texture2D Texture {get; private set; }
public TimeSpan Duration { get; private set; }
public Animation(Rectangle[] sourceRects, Texture2D texture, TimeSpan duration)
{
for (int i = 0; i < sourceRects.Length; i++)
{
sourceRects[i] = new Rectangle((sourceRects.Length - 1 - i) * (Texture.Width / sourceRects.Length), 0, Texture.Width / sourceRects.Length, Texture.Height);
}
SourceRects = sourceRects;
Texture = texture;
Duration = duration;
}
public void Update(GameTime dt)
{
PassedTime += dt.ElapsedGameTime;
if (PassedTime > Duration)
{
PassedTime -= Duration; // zurücksetzen
}
var percent = PassedTime.TotalSeconds / Duration.TotalSeconds;
_animIndex = (int)Math.Round(percent * (SourceRects.Length - 1));
}
public void Draw(SpriteBatch batch)
{
batch.Draw(Texture, new Rectangle(0, 0, Texture.Width / SourceRects.Length, Texture.Height), SourceRects[_animIndex], Color.White);
}
}
Game1 class code:
public class Game1 : Microsoft.Xna.Framework.Game
{
GraphicsDeviceManager graphics;
SpriteBatch spriteBatch;
Animation animation;
Texture2D gegner;
Rectangle[] gegnerbilder = new Rectangle[10];
public Game1()
{
graphics = new GraphicsDeviceManager(this);
Content.RootDirectory = "Content";
}
protected override void Initialize()
{
base.Initialize();
}
protected override void LoadContent()
{
spriteBatch = new SpriteBatch(GraphicsDevice);
gegner = Content.Load<Texture2D>("kurzeanim");
}
protected override void Update(GameTime gameTime)
{
KeyboardState kbState = Keyboard.GetState();
if (kbState.IsKeyDown(Keys.A))
{
animation = new Animation(gegnerbilder, gegner, TimeSpan.FromSeconds(3));
animation.Update(gameTime);
}
base.Update(gameTime);
}
protected override void Draw(GameTime gameTime)
{
GraphicsDevice.Clear(Color.CornflowerBlue);
spriteBatch.Begin();
animation.Draw(spriteBatch);
spriteBatch.End();
base.Draw(gameTime);
}
}

Your field animation is not initialized and you are calling its instance method Draw that is why you are getting this exception. At that particular line it is null. It is being initialized in update method, you may initialize it in the constructor to avoid that exception

Ensure that the Update-method of the Game1-class is called before the Draw-method of that class or ensure that animation is not null before calling its members:
protected override void Draw(GameTime gameTime)
{
if (animation != null)
{
GraphicsDevice.Clear(Color.CornflowerBlue);
spriteBatch.Begin();
animation.Draw(spriteBatch);
spriteBatch.End();
}
base.Draw(gameTime);
}

You only ever instantiate the animation property if the A key is depressed when Update is called.
protected override void Update(GameTime gameTime)
{
KeyboardState kbState = Keyboard.GetState();
if (kbState.IsKeyDown(Keys.A))
{
animation = new Animation(gegnerbilder, gegner, TimeSpan.FromSeconds(3));
animation.Update(gameTime);
}
base.Update(gameTime);
}
You need to initialise it earlier (e.g. in the constructor) or add some logic to the Draw method to check for null values.

animation = new Animation(gegnerbilder, gegner, TimeSpan.FromSeconds(3));
Are you really creating a new animation and updating it every Update() That could be 60 Times per second.
You are going to need to add it to your Initialize() Method (Or whenever you need to change the animation)
Then in update you can still do animation.Update() but without the constructor.

I am getting a null error

I am getting an error message in this line:
player = new Player(this.Content.Load<Texture2D>("Player"),
actor.position,
this.spriteBatch,
enemyManager);
which tells me the actor object is null. How can I overcome this situation?
The exact error is:
Field Shmup.MyGame.actor is never assigned to, and will always have its default value null.
Here is my code:
class MyGame // [edit:] added based on below constructor
{
GraphicsDeviceManager graphics;
SpriteBatch spriteBatch;
Player player;
EnemyManager enemyManager;
Actor actor;
public MyGame()
{
graphics = new GraphicsDeviceManager(this);
IsMouseVisible = true;
Content.RootDirectory = "Content";
}
protected override void Initialize()
{
// TODO: Add your initialization logic here
base.Initialize();
}
protected override void LoadContent()
{
// Create a new SpriteBatch, which can be used to draw textures.
spriteBatch = new SpriteBatch(GraphicsDevice);
startTheGame();
}
protected override void UnloadContent()
{
// TODO: Unload any non ContentManager content here
}
protected override void Update(GameTime gameTime)
{
// Allows the game to exit
if (GamePad.GetState(PlayerIndex.One).Buttons.Back == ButtonState.Pressed)
{
this.Exit();
}
this.player.Update(gameTime);
this.enemyManager.Update(gameTime);
base.Update(gameTime);
}
protected override void Draw(GameTime gameTime)
{
GraphicsDevice.Clear(Color.Maroon);
this.spriteBatch.Begin();
this.player.Draw(gameTime);
this.enemyManager.Draw(gameTime);
this.spriteBatch.End();
base.Draw(gameTime);
}
void startTheGame()
{
enemyManager = new EnemyManager(this.Content.Load<Texture2D>("Enemy"), new Vector2(16), this.spriteBatch);
player = new Player(this.Content.Load<Texture2D>("Player"),actor.position, this.spriteBatch, enemyManager);
enemyManager.StartTheGame(10);
}
}
public class Actor
{
public Texture2D texture;
public Vector2 origin;
public SpriteBatch spriteBatch;
public Vector2 position;
public Rectangle boundingRectangle;
public Vector2 Position
{
get { return position; }
set
{
position = value;
boundingRectangle = new Rectangle((Int32)(position.X - origin.X), (Int32)(position.Y - origin.Y), texture.Width, texture.Height);
}
}
public Rectangle BoundingRectangle
{
get { return boundingRectangle; }
}
public Actor(Texture2D texture, Vector2 origin, SpriteBatch spriteBatch, Vector2 initialPosition)
{
this.texture = texture;
this.origin = origin;
this.spriteBatch = spriteBatch;
this.position = initialPosition;
boundingRectangle = new Rectangle((Int32)(initialPosition.X - origin.X), (Int32)(initialPosition.Y - origin.Y), texture.Width, texture.Height);
}
public virtual void Update(GameTime gameTime)
{ }
public virtual void Draw(GameTime gameTime)
{
this.spriteBatch.Draw(texture, position - origin, Color.White);
}
}

Like error says, you need to create an instance of Actor class.
In game constructor or in startTheGame Method(before creating an instance of Player class) you should create an instance of Actor class, something like :
this.actor = new Actor(variables...);

Error on xna "is inaccessible due to its protection level"

I am getting an error when I try to get the mouse position.
This is my player class. I am trying to make the player sprite move by mouse cursor
class Player : Actor
{
public MouseState mState;
EnemyManager enemyManager;
public Player(Texture2D texture, Vector2 origin, SpriteBatch spriteBatch, EnemyManager enemyManager)
: base(texture, origin, spriteBatch, new Vector2(250.0f, 516.0f))
{
this.enemyManager = enemyManager;
}
public override void Update(GameTime gameTime)
{
//KeyboardState keyboardState = Keyboard.GetState();
//if (keyboardState.IsKeyDown(Keys.Left))
//{
// if (this.Position.X > 32.0f)
// {
// this.Position -= 10.0f * Vector2.UnitX;
// }
//}
//if (keyboardState.IsKeyDown(Keys.Right))
//{
// if (this.Position.X < 748.0f)
// {
// this.Position += 10.0f * Vector2.UnitX;
// }
//}
MouseState mState = Mouse.GetState();
this.Position = new Vector2(mState.x, mState.y);
// Collisions...
foreach (Enemy e in this.enemyManager.Enemies)
{
if (this.BoundingRectangle.Intersects(e.BoundingRectangle))
{
e.OnHit();
break;
}
}
base.Update(gameTime);
}
}
and this is my Actor class which has position variables
namespace Shmup
{
public class Actor
{
public Texture2D texture;
public Vector2 origin;
public SpriteBatch spriteBatch;
public Vector2 position;
public Rectangle boundingRectangle;
public Vector2 Position
{
get { return position; }
set { position = value; }
}
public Rectangle BoundingRectangle
{
get { return boundingRectangle; }
}
public Actor(Texture2D texture, Vector2 origin, SpriteBatch spriteBatch, Vector2 initialPosition)
{
this.texture = texture;
this.origin = origin;
this.spriteBatch = spriteBatch;
this.position = initialPosition;
boundingRectangle = new Rectangle((Int32)(initialPosition.X - origin.X), (Int32)(initialPosition.Y - origin.Y), texture.Width, texture.Height);
}
public virtual void Update(GameTime gameTime)
{
}
public virtual void Draw(GameTime gameTime)
{
this.spriteBatch.Draw(texture, position - origin, Color.White);
}
}
}
my main class
public class MyGame : Microsoft.Xna.Framework.Game
{
GraphicsDeviceManager graphics;
SpriteBatch spriteBatch;
Player player;
EnemyManager enemyManager;
Actor actor;
public MyGame()
{
graphics = new GraphicsDeviceManager(this);
IsMouseVisible = true;
Content.RootDirectory = "Content";
}
protected override void Initialize()
{
// TODO: Add your initialization logic here
Actor actor = new Actor();
base.Initialize();
}
protected override void LoadContent()
{
// Create a new SpriteBatch, which can be used to draw textures.
spriteBatch = new SpriteBatch(GraphicsDevice);
startTheGame();
}
protected override void UnloadContent()
{
// TODO: Unload any non ContentManager content here
}
protected override void Update(GameTime gameTime)
{
// Allows the game to exit
if (GamePad.GetState(PlayerIndex.One).Buttons.Back == ButtonState.Pressed)
{
this.Exit();
}
this.player.Update(gameTime);
this.enemyManager.Update(gameTime);
base.Update(gameTime);
}
protected override void Draw(GameTime gameTime)
{
GraphicsDevice.Clear(Color.Maroon);
this.spriteBatch.Begin();
this.player.Draw(gameTime);
this.enemyManager.Draw(gameTime);
this.spriteBatch.End();
base.Draw(gameTime);
}
void startTheGame()
{
enemyManager = new EnemyManager(this.Content.Load<Texture2D>("Enemy"), new Vector2(16), this.spriteBatch);
player = new Player(this.Content.Load<Texture2D>("Player"),actor.position, this.spriteBatch, enemyManager);
enemyManager.StartTheGame(10);
}
}

This line is the problem I think:
this.Position = new Vector2(mState.x, mState.y);
x and y are not publicly exposed on MouseState. You need to capitalize them (C# is case-sensitive). Use this instead:
this.Position = new Vector2(mState.X, mState.Y);

"making these changes gives me a different error Object reference not set to an instance of an object in the line player = new Player(this.Content.Load("Player"),actor.position, this.spriteBatch, enemyManager); on my main class it says Error 'Shmup.Actor' does not contain a constructor that takes 0 arguments –"
The constructor for Actor requires - Texture2D texture, Vector2 origin, SpriteBatch spriteBatch, Vector2 initialPosition .
So you would need to change the "Actor actor = new Actor();" into LoadContent() or a separate method after you have supplied all the information required to declare a new Actor.
It should read something along these lines(replace each argument with the proper item from your game class):
Actor actor = new Actor( texture, origin, spriteBatch, initialPosition);
If you do that it will fix the error, If you don't you will continue to get the error unless you define a constructor in Actor that takes 0 arguments. Hope this helps somewhat.