I'm pretty new to programming. I'm developing a 2D game using monogame where you have to run around killing enemies and jumping from one moving tile to another trying not to fall on the spikes and die.
I almost have everything of the mechanics, collision. I want to start making multiple levels, a beginscreen where you have to press s to start and when you die a gameover screen.
I have implemented gamestates. the program starts on the first state(menu) where you get a picture that says press S to start but when i press S to start the program crashes and I get a null reference exeption... but if I don't use the menu state as the first state and instead I use the level1 gamestate the game works so there is no null reference exeption (but you don't get the menuscreen of course).
I'm doing something wrong but i cant find it. I will paste my game1.cs below. I think that's where the problem is. if you need something else please ask.
please help, thanks in advance. ps: sorry for the large amount of code but the problem could be everywhere
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Graphics;
using Microsoft.Xna.Framework.Input;
using System.Collections.Generic;
namespace ninjaprincess
{
/// <summary>
/// This is the main type for your game.
/// </summary>
public class Game1 : Game
{
//Game states http://community.monogame.net/t/switch-scenes-in-monogame/2605
enum GameState
{
Menu,
GamePlayLevel1,
EndGame
}
GameState _state;
GraphicsDeviceManager graphics;
SpriteBatch spriteBatch;
Hero ninja;
private Texture2D ninjasprite;
private Texture2D background;
private LevelDesign level;
private Texture2D StartScreen;
Camera camera;
bool start;
List<Knife> knives = new List<Knife>();
KeyboardState pastkey;
public Game1()
{
graphics = new GraphicsDeviceManager(this);
Content.RootDirectory = "Content";
/// dit toevoegen voor fullscreen////
graphics.PreferredBackBufferHeight = 1080;
graphics.PreferredBackBufferWidth = 1920;
graphics.IsFullScreen = true;
}
protected override void Initialize()
{
camera = new Camera(GraphicsDevice.Viewport);
base.Initialize();
}
protected override void LoadContent()
{
spriteBatch = new SpriteBatch(GraphicsDevice);
level = new LevelDesign();
background = Content.Load<Texture2D>("background");
ninja = new Hero(ninjasprite, new Vector2(10, 20));
ninja.Content(Content);
level.content = Content;
StartScreen = Content.Load<Texture2D>("Startscherm");
Block.Content = Content;
level.tileArray = new byte[,]
{
{ 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0},
{ 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0},
{ 0,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0},
{ 0,0,0,0,0,0,0,0,0,0,0,1,1,1,0,0,1,0,0,1,1,0,0,0,0,0,0,0,0,0,0,0,0},
{ 0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,4,4,0,4,4,4,0,0,0,0},
{ 0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,4,0},
{ 0,0,0,0,0,0,1,1,1,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,1,0,0,0,0,0},
{ 0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0},
{ 0,0,1,1,1,0,0,0,0,0,1,1,2,2,2,2,2,2,2,2,2,2,2,2,2,2,0,0,0,0,0,0,0}
};
level.CreateWorld(105);
ninja.controllers = new KeyboardArrows();
}
/// <summary>
/// UnloadContent will be called once per game and is the place to unload
/// game-specific content.
/// </summary>
protected override void UnloadContent()
{
// TODO: Unload any non ContentManager content here
}
/// <param name="gameTime">Provides a snapshot of timing values.</param>
protected override void Update(GameTime gameTime)
{
if (GamePad.GetState(PlayerIndex.One).Buttons.Back == ButtonState.Pressed || Keyboard.GetState().IsKeyDown(Keys.Escape))
Exit();
if (_state == GameState.GamePlayLevel1)
{
camera.Update(ninja.Position, level.Width + 400, 1080);
ninja.Update(gameTime);
if (ninja.controllers.shooting && pastkey.IsKeyUp(Keys.Space))
{
ShootKnife();
}
pastkey = Keyboard.GetState();
UpdateKnife();
foreach (Block block in level.blockArray)
{
if (block is Grass)
{
ninja.CollideOnGrass(block.Rectangle);
}
if (block is Spikes)
{
ninja.CollideOnSpikes(block.Rectangle);
}
if (block is MovingGrassLeft)
{
ninja.CollideOnGrass(block.Rectangle);
block.Update(gameTime);
}
}
foreach (Enemy enemy in level.enemyArray)
{
if (enemy is Enemy)
{
ninja.CollideOnEnemy(enemy.EnemyRectangle, 2840, 1080, level.enemyArray, (enemy.EnemyRectangle.X - (enemy.EnemyRectangle.Width / 3)), enemy.EnemyRectangle.Y + (enemy.EnemyRectangle.Height / 2));
enemy.Update(gameTime);
}
}
if (ninja.isAlive == false)
{
_state = GameState.EndGame;
}
}
base.Update(gameTime);
switch (_state)
{
case GameState.Menu:
UpdateMenu(gameTime);
break;
case GameState.GamePlayLevel1:
UpdateGameplay(gameTime);
break;
case GameState.EndGame:
UpdateEndGame(gameTime);
break;
}
}
void UpdateMenu(GameTime gametime)
{
KeyboardState keyState = Keyboard.GetState();
if (keyState.IsKeyDown(Keys.S))
_state = GameState.GamePlayLevel1;
else if (keyState.IsKeyDown(Keys.Q))
Exit();
}
void UpdateGameplay(GameTime gametime)
{
KeyboardState keyState = Keyboard.GetState();
if (keyState.IsKeyDown(Keys.Escape))
_state = GameState.Menu;
}
void UpdateEndGame(GameTime gametime)
{
KeyboardState keyState = Keyboard.GetState();
if (keyState.IsKeyDown(Keys.Q))
Exit();
if (keyState.IsKeyDown(Keys.S))
_state = GameState.GamePlayLevel1;
}
public void UpdateKnife()
{
foreach (Knife knife in knives)
{
knife.position.X += 25f;
for (int i = 1; i < knives.Count; i++)
{
if (knives[i].isVisible == false)
{
knives.RemoveAt(i);
i--;
}
}
}
}
public void ShootKnife()
{
Knife newKnife = new Knife(Content.Load<Texture2D>("KunaiRight"));
newKnife.isVisible = true;
newKnife.velocity.X = 3f;
newKnife.position = new Vector2(ninja.Position.X, ninja.Position.Y + (ninja.PlayerRectangle.Height / 2));
if (knives.Count < 50)
{
knives.Add(newKnife);
}
}
/// <param name="gameTime">Provides a snapshot of timing values.</param>
protected override void Draw(GameTime gameTime)
{
GraphicsDevice.Clear(Color.White);
switch (_state)
{
case GameState.Menu:
DrawMenu(gameTime);
break;
case GameState.GamePlayLevel1:
DrawGamePlayLevel1(gameTime);
break;
case GameState.EndGame:
DrawEndGame(gameTime);
break;
}
base.Draw(gameTime);
}
void DrawMenu(GameTime GameTime)
{
spriteBatch.Begin();
spriteBatch.Draw(StartScreen, new Rectangle(0, 0, 1920, 1080), Color.AliceBlue);
spriteBatch.End();
}
void DrawGamePlayLevel1(GameTime GameTime)
{
GraphicsDevice.Clear(Color.White);
spriteBatch.Begin();
spriteBatch.Draw(background, new Rectangle(0, 0, 1920, 1080), Color.White);
spriteBatch.End();
spriteBatch.Begin(SpriteSortMode.Deferred, BlendState.AlphaBlend, null, null, null, null, camera.Transform);
level.DrawLevel(spriteBatch);
ninja.Draw(spriteBatch);
foreach (Knife knife in knives)
{
knife.Draw(spriteBatch);
}
spriteBatch.End();
}
void DrawEndGame(GameTime GameTime)
{
spriteBatch.Begin();
spriteBatch.Draw(StartScreen, new Rectangle(0, 0, 1920, 1080), Color.White);
spriteBatch.End();
}
}
}
