Hey,
In my program there is some bombs generating, but on start, after adding new one to list, it should set bomb's parameters but throws "Object reference not set to an instance" error. . After a long time I still cant figure out the mistake.
Below there's all of the relevant code.
Base class:
namespace Monogame_SprDeathRespawn
{
public class Game1 : Game
{
GraphicsDeviceManager graphics;
SpriteBatch spriteBatch;undefined> public static int screenWidth;
public static int screenHeight;
public static Random random;
public List<SpriteClass> sprites= new List<SpriteClass>();
public bool hasStarted= false;
public Texture2D bombTexture;
private float timer;
public Game1()
{
graphics = new GraphicsDeviceManager(this);
Content.RootDirectory = "Content";
screenHeight = graphics.PreferredBackBufferHeight;
screenWidth = graphics.PreferredBackBufferHeight;
}
protected override void Initialize()
{
base.Initialize();
}
protected override void LoadContent()
{
spriteBatch = new SpriteBatch(GraphicsDevice);
bombTexture = Content.Load<Texture2D>("bomb");
Restart();
}
private void Restart()
{
var playerTexture = Content.Load<Texture2D>("randomManSpr");
sprites = new List<SpriteClass>
{
new Player(playerTexture) { position = new Vector2(screenWidth / 2 - playerTexture.Width / 2, screenHeight - playerTexture.Height),
input = new Input() { left = Keys.A, right = Keys.D }, speed = 10f }
};
hasStarted = false;
}
protected override void UnloadContent()
{
}
protected override void Update(GameTime gameTime)
{
if (Keyboard.GetState().IsKeyDown(Keys.Space))
hasStarted = true;
if (hasStarted != true)
return;
timer += (float)gameTime.ElapsedGameTime.TotalSeconds;
foreach (var sprite in sprites)
{
sprite.Update(gameTime, sprites);
}
if (timer > 0.25f)
{
timer = 0;
sprites.Add(new Bomb(Content.Load<Texture2D>("bomb")));
}
for (int i = 0; i < sprites.Count; i++)
{
var sprite = sprites[i];
if (sprite.isRemoved)
{
sprites.RemoveAt(i);
i--;
}
if (sprite is Player)
{
var player = sprite as Player;
if (player.hasDied)
Restart();
}
}
base.Update(gameTime);
}
protected override void Draw(GameTime gameTime)
{
GraphicsDevice.Clear(Color.CornflowerBlue);
spriteBatch.Begin();
foreach (var sprite in sprites)
{
sprite.Draw(spriteBatch);
}
spriteBatch.End();
base.Draw(gameTime);
}
}
}
Sprite class:
namespace Monogame_SprDeathRespawn.Sprite
{
public class SpriteClass
{
protected Texture2D texture;
public Vector2 position;
public Vector2 velocity;
public float speed;
public Input input;
public bool isRemoved = false;
public Rectangle rectangle
{
get
{
return new Rectangle((int)position.X, (int)position.Y, texture.Width, texture.Height);
}
}
public SpriteClass(Texture2D texture)
{
this.texture = texture;
}
public virtual void Update(GameTime gameTime, List<SpriteClass> sprites)
{
}
public virtual void Draw(SpriteBatch spriteBatch)
{
spriteBatch.Draw(texture, position, Color.White);
}
}
}
Bomb class derived from Sprite:
namespace Monogame_SprDeathRespawn.Sprite
{
class Bomb : SpriteClass
{
public Bomb(Texture2D texture)
: base(texture)
{
this.position = new Vector2(Game1.random.Next(0, Game1.screenWidth + texture.Width), -texture.Height); //throws "Object reference not set to an instance" exception
speed = Game1.random.Next(3, 10); //throws the exception if line above commented
}
public override void Update(GameTime gameTime, List<SpriteClass> sprites)
{
position.Y += speed;
if (rectangle.Bottom >= Game1.screenHeight)
isRemoved = true;
}
}
}
Thanks for helping.
