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(Xna) My players position won't update, I need it for my enemy to follow

enter code hereWhen im drawing it to a string it just stays at 300,300 . My mouse always updates its Vector2 position.X, position.Y. I need to be able to update my players position or my enemy wont follow my player. It just goes to that certain player position i set for it. PLEASE HELP AND THANK YOU!
class Enemy
{
Player p = new Player();
public Vector2 direction, velocity,position;
public float speed;
public Texture2D texture;
public Enemy()
{
speed = 1;
texture = null;
position = new Vector2(600, 500);
}
public void LoadContent(ContentManager Content)
{
texture = Content.Load<Texture2D>("circle");
}
public void Update(GameTime gameTime)
{
MouseState mouse = Mouse.GetState();
direction = p.position - position;
direction.Normalize();
velocity = direction * speed;
position += velocity;
}
public void Draw(SpriteBatch spriteBatch)
{
spriteBatch.Draw(texture, position, Color.Red);
}
/*
direction = p.position - position;
direction.Normalize();
velocity = direction * speed;
position += velocity;
*/
}
class Player
{
public float rotation, bulletDelay;
public Vector2 position,velocity,origin;
public string spriteName;
public Texture2D texture,bulletTexture;
List<Bullets> bullets = new List<Bullets>();
public float speed = 10;
public float health = 100;
public Player()
{
texture = null;
spriteName = "playerover";
position = new Vector2(300, 300);
bulletDelay = 20;
}
public void LoadContent(ContentManager Content)
{
texture = Content.Load<Texture2D>(spriteName);
bulletTexture = Content.Load<Texture2D>("playerbullet");
}
public void Draw(SpriteBatch spriteBatch)
{
origin = new Vector2(texture.Width / 2, texture.Height / 2);
spriteBatch.Draw(texture, new Rectangle((int)position.X, (int)position.Y, texture.Width, texture.Height), null, Color.White, rotation,new Vector2(texture.Width / 2, texture.Height / 2), SpriteEffects.None, 0);
foreach (Bullets bullet in bullets)
{
bullet.Draw(spriteBatch);
}
}
public void Update(GameTime gameTime)
{
MouseState curMouse = Mouse.GetState();
KeyboardState keyState = Keyboard.GetState();
Vector2 mouseLoc = new Vector2(curMouse.X, curMouse.Y);
Vector2 direction = mouseLoc - position;
rotation = (float)(Math.Atan2(direction.Y, direction.X));
if (keyState.IsKeyDown(Keys.W))
{
position.Y -= speed;
}
if (keyState.IsKeyDown(Keys.S))
{
position.Y += speed;
}
if (keyState.IsKeyDown(Keys.A))
{
position.X -= speed;
}
if (keyState.IsKeyDown(Keys.D))
{
position.X += speed;
}
if (curMouse.LeftButton == ButtonState.Pressed)
{
Shoot();
}
UpdateBullets();
}
public void UpdateBullets()
{
foreach (Bullets bullet in bullets)
{
bullet.position += bullet.velocity;
if (bullet.position.Y <= 5)
{
bullet.isVisible = false;
}
if (bullet.position.X <= 5)
{
bullet.isVisible = false;
}
if (bullet.position.X >= 785)
{
bullet.isVisible = false;
}
if (bullet.position.Y >= 575)
{
bullet.isVisible = false;
}
}
for (int i = 0; i < bullets.Count; i++)
{
if (!bullets[i].isVisible)
{
bullets.RemoveAt(i);
i--;
}
}
}
public void Shoot()
{
if (bulletDelay >= 0)
bulletDelay--;
if (bulletDelay <= 0)
{
Bullets newBullet = new Bullets(bulletTexture);
newBullet.velocity = new Vector2((float)Math.Cos(rotation), (float)Math.Sin(rotation)) * 5f + velocity;
newBullet.position = position + newBullet.velocity * 5;
newBullet.isVisible = true;
if (bullets.Count < 20)
{
bullets.Add(newBullet);
}
}
if (bulletDelay == 0)
{
bulletDelay = 20;
}
}
}
class Hud
{
public SpriteFont font;
public bool showHud;
Player p = new Player();
Enemy e = new Enemy();
public Hud()
{
showHud = true;
}
public void LoadContent(ContentManager Content)
{
font = Content.Load<SpriteFont>("font");
}
public void Draw(SpriteBatch spriteBatch)
{
MouseState mouse = Mouse.GetState();
if (showHud)
{
spriteBatch.DrawString(font, "Mouse.X = " + mouse.X, new Vector2(10, 0), Color.White);
spriteBatch.DrawString(font, "Mouse.Y = " + mouse.Y, new Vector2(10, 20), Color.White);
spriteBatch.DrawString(font, "Health = " + p.health, new Vector2(10, 40), Color.White);
spriteBatch.DrawString(font, "Pos.Y = " + p.position.Y, new Vector2(10, 60), Color.White);
spriteBatch.DrawString(font, "Pos.X = " + p.position.X, new Vector2(10, 80), Color.White);
}
}
}

I didn't read all the code you posted, but it seems that you created a new separate instance for the player in the Enemy class which is never updated.
class Enemy
{
Player p = new Player();
//...
}
You should either take a Vector2 for the players position into your enemies Update method or handle the enemy movement somewhere else. Perhaps you could have a method in your Enemy class named Follow taking a Player object as a parameter, then you could do something like the following in the place where you handle all entity movement. It would look roughly like this:
public void UpdateEntities(GameTime gameTime)
{
player.Update(gameTime);
enemy.Update(gameTime);
if(PlayerDistanceFromEnemy() < 50)
enemy.Follow(player);
}
That is a very rough guideline and probably something you'd want to rewrite later on, but it will work.
as for the Follow method in your enemy class:
public void Follow(Player player)
{
this.p = player;
}
public void Update(GameTime gameTime)
{
if(p != null)
{
//do stuff
}
}
This will work, but you have to work on the structure of your code if you want to expand. I might update this answer later with a better solution if someone doesn't do it before me.

How do i check if there are no key inputs on xna

public class Game1 : Microsoft.Xna.Framework.Game
{
GraphicsDeviceManager graphics;
SpriteBatch spriteBatch;
Texture2D walkRight, walkUp, walkLeft, walkDown, currentWalk, TitleScreen, stand;
Rectangle destRect;
Rectangle sourceRect;
KeyboardState ks;
Vector2 position = new Vector2();
bool isGrounded;
bool isStanding;
float fallSpeed = 5;
enum GameStates { Titlescreen, Playing, PlayerDead, GameOver };
GameStates gameStates = GameStates.Titlescreen;
float elapsed;
float delay = 200f;
int frames = 0;
public Game1()
{
graphics = new GraphicsDeviceManager(this);
Content.RootDirectory = "Content";
}
protected override void Initialize()
{
destRect = new Rectangle(50, 50, 50, 50);
base.Initialize();
}
protected override void LoadContent()
{
spriteBatch = new SpriteBatch(GraphicsDevice);
walkRight = Content.Load<Texture2D>("walkRight");
walkUp = Content.Load<Texture2D>("walkUp");
walkLeft = Content.Load<Texture2D>("walkLeft");
walkDown = Content.Load<Texture2D>("walkDown");
TitleScreen = Content.Load<Texture2D>("TitleScreen");
stand = Content.Load<Texture2D>("SpriteStill");
currentWalk = walkRight;
}
protected override void UnloadContent()
{
}
private void Animate(GameTime gameTime)
{
elapsed += (float)gameTime.ElapsedGameTime.TotalMilliseconds;
if (elapsed >= delay)
{
if (frames >= 3)
{
frames = 0;
}
else
{
frames++;
}
elapsed = 0;
}
sourceRect = new Rectangle(50 * frames, 0, 50, 50);
}
protected override void Update(GameTime gameTime)
//{
//switch (gameStates)
{
if (position.Y >= Window.ClientBounds.Height - 50)
{
position.Y = Window.ClientBounds.Height - 50;
isGrounded = true;
}
if (position.X >= Window.ClientBounds.Width - 50)
{
position.X = Window.ClientBounds.Width - 50;
}
if (position.X <=0)
{
position.X = 0;
}
if (position.Y <= 0)
{
position.Y = 0;
}
ks = Keyboard.GetState();
if (ks.IsKeyDown(Keys.Right))
{
position.X += 3f;
currentWalk = walkRight;
}
if (ks.IsKeyDown(Keys.Left))
{
position.X -= 3f;
currentWalk = walkLeft;
}
if (ks.IsKeyDown(Keys.Down))
{
position.Y += 3f;
currentWalk = walkDown;
}
Animate(gameTime);
destRect = new Rectangle((int)position.X, (int)position.Y, 50, 50);
FallManagement(gameTime);
base.Update(gameTime);
}
protected override void Draw(GameTime gameTime)
{
GraphicsDevice.Clear(Color.CornflowerBlue);
spriteBatch.Begin();
spriteBatch.Draw(currentWalk, destRect, sourceRect, Color.White);
spriteBatch.End();
base.Draw(gameTime);
}
void FallManagement(GameTime gameTime)
{
position.Y += fallSpeed;
if (isGrounded == false)
{
fallSpeed = 5;
}
if (ks.IsKeyDown(Keys.Up) && isGrounded)
{
fallSpeed -= 40;
isGrounded = false;
}
}
}
I am currently creating a very basic XNA platform game for a year one college course. I am currently trying to add in a statement that says if no keys are pressed then load up texture 2d for the character standing still, but I'm not sure how to check if the there are no keys pressed at all. Basically I would like to check if the character is moving and if not the texture for the character would be set to the standing still png, does anyone know how I might do this. I have put the entire code into this question because I am not using a character class and my level of coding is extremely basic at current.

Maybe something like this would work for you:
ks = Keyboard.GetState();
bool isMoving = false;
if (ks.IsKeyDown(Keys.Right))
{
position.X += 3f;
currentWalk = walkRight;
isMoving = true;
}
if (ks.IsKeyDown(Keys.Left))
{
position.X -= 3f;
currentWalk = walkLeft;
isMoving = true;
}
if (ks.IsKeyDown(Keys.Down))
{
position.Y += 3f;
currentWalk = walkDown;
isMoving = true;
}
if (!isMoving)
{
//Do whatever you need to do when the player is still here
}
Basically set a flag when any key is pressed that you handle, and then use that flag later to do what you need to do when no key is pressed.
Or, if you want to check that no key is pressed what-so-ever:
if (ks.GetPressedKeys() == null || ks.GetPressedKeys().Length == 0)
{
//No keys pressed at all. (not sure if GetPressedKeys returns null
//or zero length array, check when in debug then remove one.
}

When implementing simple Pong AI, two paddles are created and flicker

So, me being a new programmer, instead doing actual AI implementation, I used the following solution for making paddle on the right follow the ball:
if(ball.position.Y > p2.position.Y)
{
p2.position.Y += ball.position.Y;
}
else if (ball.position.Y < p2.position.Y)
{
p2.position.Y -= ball.position.Y;
}
However this happens (okay I tried taking a screencap with PrtScn and it semmed to pause the game for a microsecond and capture a single paddle instead of two flickering ones)
So what can I do to make the paddle 2 appear as one?
Full Code of Program:
Game1.cs
namespace Pong
{
public class Game1 : Game
{
//Variables
GraphicsDeviceManager graphics;
SpriteBatch spriteBatch;
//Borders
Texture2D borders;
//Paddles
Paddle p1 = new Paddle();
Paddle p2 = new Paddle();
//Ball
Ball ball = new Ball();
//Positions
Vector2 bordersPos;
//Constructor
public Game1()
: base()
{
graphics = new GraphicsDeviceManager(this);
graphics.IsFullScreen = false;
graphics.PreferredBackBufferHeight = 800;
graphics.PreferredBackBufferWidth = 800;
//Content Loader
Content.RootDirectory = "Content";
}
//Initialize
protected override void Initialize()
{
base.Initialize();
}
//Load Content
protected override void LoadContent()
{
spriteBatch = new SpriteBatch(GraphicsDevice);
//Assigning Textures
p1.texture = Content.Load<Texture2D>("paddle1");
p2.texture = Content.Load<Texture2D>("paddle1");
borders = Content.Load<Texture2D>("borders");
ball.texture = Content.Load<Texture2D>("ball");
//Positions
p1.position.X = 50;
p1.position.Y = graphics.GraphicsDevice.Viewport.Height / 2 - (p1.height / 2);
p2.position.X = graphics.GraphicsDevice.Viewport.Width - 50 - p2.width;
p2.position.Y = graphics.GraphicsDevice.Viewport.Height / 2 - (p2.height / 2);
bordersPos.Y = 0;
bordersPos.X = 0;
ball.position.X = 800 / 2 - ball.width / 2;
ball.position.Y = 800 / 2 - ball.height / 2;
}
protected override void UnloadContent()
{
}
//Update
protected override void Update(GameTime gameTime)
{
//Exit
if (Keyboard.GetState().IsKeyDown(Keys.Escape))
Exit();
//Update Player Controls
PlayerInput();
p1.Update();
p2.Update();
ball.Update();
//Paddle Collision
if (padCol1())
{
if (ball.movingDownLeft)
{
ball.movingDownRight = true;
ball.movingDownLeft = false;
}
else if (ball.movingUpLeft)
{
ball.movingUpRight = true;
ball.movingUpLeft = false;
}
}
if (padCol2())
{
if (ball.movingDownRight)
{
ball.movingDownLeft = true;
ball.movingDownRight = false;
}
else if (ball.movingUpRight)
{
ball.movingUpLeft = true;
ball.movingUpRight = false;
}
}
//AI
if(ball.position.Y > p2.position.Y){
p2.position.Y += ball.position.Y;
}
else if (ball.position.Y < p2.position.Y)
{
p2.position.Y -= ball.position.Y;
}
base.Update(gameTime);
}
//Draw
protected override void Draw(GameTime gameTime)
{
GraphicsDevice.Clear(Color.Black);
spriteBatch.Begin(SpriteSortMode.BackToFront, BlendState.AlphaBlend);
//Paddles
p1.Draw(spriteBatch);
p2.Draw(spriteBatch);
//Borders
spriteBatch.Draw(borders, bordersPos, Color.White);
//Ball
ball.Draw(spriteBatch);
spriteBatch.End();
base.Draw(gameTime);
}
//Player Input
public void PlayerInput()
{
//Player 1
if (Keyboard.GetState(p1.pNumber).IsKeyDown(Keys.W))
{
p1.position.Y -= p1.speed;
}
else if (Keyboard.GetState(p1.pNumber).IsKeyDown(Keys.S))
{
p1.position.Y += p1.speed;
}
}
//Paddle Collision
public bool padCol1()
{
if (ball.position.Y >= p1.position.Y && ball.position.X > p1.position.X && ball.position.X < (p1.position.X + p1.width) && ball.position.Y < (p1.position.Y + p1.height))
{
return true;
}
else
return false;
}
public bool padCol2()
{
if (ball.position.Y >= p2.position.Y && ball.position.X > p2.position.X && ball.position.X < (p2.position.X + p2.width) && ball.position.Y < (p2.position.Y + p2.height))
{
return true;
}
else
return false;
}
}
}
Paddle.cs
namespace Pong
{
class Paddle : Game
{
//Variables
public Texture2D texture;
public Vector2 position;
public PlayerIndex pNumber;
public int width, height;
public float speed;
//Constructor
public Paddle()
{
texture = null;
position = Vector2.Zero;
pNumber = PlayerIndex.One;
width = 64;
height = 187;
speed = 10.0f;
}
//Update
public void Update()
{
//Set Boundaries
if (position.Y <= 30)
position.Y = 30;
if (position.Y >= 800 - 217)
position.Y = 800 - 217;
}
//Draw
public void Draw(SpriteBatch spriteBatch)
{
spriteBatch.Draw(texture, position, Color.White);
}
}
}
Ball.cs
namespace Pong
{
class Ball : Game
{
//Variables
public Vector2 position;
public Texture2D texture;
public int width, height;
public float speed;
public bool movingDownLeft, movingUpLeft, movingDownRight, movingUpRight;
//Constructor
public Ball()
{
Content.RootDirectory = ("Content");
speed = 6.0f;
width = 20;
height = 20;
movingDownLeft = true;
movingUpRight = false;
movingUpLeft = false;
movingDownRight = false;
position = Vector2.Zero;
}
//Draw
public void Draw(SpriteBatch spriteBatch)
{
spriteBatch.Draw(texture, position, Color.White);
}
//Update
public void Update()
{
//Directions
if(movingUpLeft){
position.Y -= speed;
position.X -= speed;
}
if (movingDownLeft)
{
position.Y += speed;
position.X -= speed;
}
if (movingUpRight)
{
position.Y -= speed;
position.X += speed;
}
if (movingDownRight)
{
position.Y += speed;
position.X += speed;
}
//Ball Wall Collision
if(movingUpLeft && position.Y <= 30)
{
movingDownLeft = true;
movingUpLeft = false;
}
//1
else if (movingDownLeft && position.X <= 0)
{
movingDownRight = true;
movingDownLeft = false;
}
//2
else if (movingUpLeft && position.X <= 0)
{
movingUpRight = true;
movingUpLeft = false;
}
//3
else if (movingDownLeft && position.Y >= 800 - 45)
{
movingUpLeft = true;
movingDownLeft = false;
}
//4
else if (movingDownRight && position.X >= 800 - width)
{
movingDownLeft = true;
movingDownRight = false;
}
//5
else if (movingUpRight && position.Y <= 30)
{
movingDownRight = true;
movingUpRight = false;
}
//6
else if (movingDownRight && position.Y >= 800 - 45)
{
movingUpRight = true;
movingDownRight = false;
}
//7
else if (movingUpRight && position.X >= 800 - width)
{
movingUpLeft = true;
movingUpRight = false;
}
}
}
}

I've never used MonoGame but this:
if(ball.position.Y > p2.position.Y)
{
p2.position.Y += ball.position.Y;
}
else if (ball.position.Y < p2.position.Y)
{
p2.position.Y -= ball.position.Y;
}
Will always overshoot, then trigger the next update.
Why don't you just do:
p2.position.Y = ball.position.Y;
EDIT: You should probably also make your input frame rate independent (unless MonoGame does this for you). It seems now you'll get higher movement speed on your paddles depending on your framerate.

Paddle and Game must not inherit from Game (GameComponent instead?). There should be only one Game object.
You should replace you booleans and complex logic with Vector2 speed describing speed of a ball, and negate its X or Y when the ball hits something.

Object reference is not set to an object

I am trying to create collision between my bullets and the enemy. I have created bounding boxes for each and placed them into their own class. However, I am getting a Null reference error in my HandleCollision function, specifically at the if statement with the bounding boxes. I will also post the rest of my code.
I discussed this with two lecturers and some peers and they asy it is because bullet and enemy are equal to null. This is because it takes a couple of seconds for the enemy to spawn and the bullet only spawns once it is fired. To counter this I added an if statement to check if the bullet or enemy is null yet it still throws up the same error.
HandleCollision Function
private void HandleCollision()//collision
{
Sprite toRemove = null;
if (bullet != null || enemyTexture != null)
{
foreach (EnemySprite e in enemyList) //checks each enemy sprite
{
if (bullet.BoundingBox.Intersects(enemy.BoundingBox))
{
enemyList.Remove(enemy); //removes enemy
//toRemove = enemy;
break;
}
}
}
}
Game1.cs
public class Game1 : Microsoft.Xna.Framework.Game
{
GraphicsDeviceManager graphics;
SpriteBatch spriteBatch;
Rectangle spriteRectangle;
Rectangle bulletBounds;
Rectangle enemyBounds;
Sprite player;
Bullets bullet;
EnemySprite enemy;
Texture2D enemyTexture;
List<EnemySprite> enemyList = new List<EnemySprite>();
List<Bullets> bulletsList = new List<Bullets>();
//Pause
bool paused = false;
Texture2D pauseTexture;
Rectangle pauseRectangle;
KeyboardState pastKey;
Vector2 enemyPos = new Vector2(100, 400);
Vector2 Position;
Vector2 Distance;
Vector2 spriteOrigin;
Vector2 spriteVelocity;
const float tangentialVelocity = 5f;
float friction = 0.1f;
float rotation;
float timer = 0f;
float dropInterval = 2f;
float speed = 4f;
float angle;
Random random;
enum GameState
{
MainMenu,
Options,
Help,
Playing,
Exit,
}
GameState CurrentGameState = GameState.MainMenu;
// Screen adjustments
int screenWidth = 800, screenHeight = 600;
cButton btnPlay;
cButtonExit btnExit;
public Game1()
{
graphics = new GraphicsDeviceManager(this);
Content.RootDirectory = "Content";
}
protected override void Initialize()
{
// TODO: Add your initialization logic here
random = new Random();
Position = new Vector2(150, 150);
this.IsMouseVisible = true;
base.Initialize();
}
protected override void LoadContent()
{
// Create a new SpriteBatch, which can be used to draw textures.
spriteBatch = new SpriteBatch(GraphicsDevice);
player = new Sprite();
player.Texture = Content.Load<Texture2D>("graphics/player");
// Screen stuff
graphics.PreferredBackBufferWidth = screenWidth;
graphics.PreferredBackBufferHeight = screenHeight;
//graphics.IsFullScreen = true;
graphics.ApplyChanges();
IsMouseVisible = true;
btnPlay = new cButton(Content.Load<Texture2D>("Graphics/play"), graphics.GraphicsDevice);
btnPlay.setPosition(new Vector2(350, 190));
btnExit = new cButtonExit(Content.Load <Texture2D>("Graphics/exit"), graphics.GraphicsDevice);
btnExit.setPosition(new Vector2(350, 220));
enemyTexture = Content.Load<Texture2D>("graphics/enemy");
player.Texture = Content.Load<Texture2D>("Graphics/player");
int screenCenterX = GraphicsDevice.Viewport.Width / 2;
player.Position = new Vector2(screenCenterX - (player.Texture.Width / 2), screenHeight - player.Texture.Height - 20);
pauseTexture = Content.Load<Texture2D>("graphics/paused");
pauseRectangle = new Rectangle(0, 0, pauseTexture.Width, pauseTexture.Height);
Bullets.BulletTexture = Content.Load<Texture2D>("graphics/bullet");
}
protected override void Update(GameTime gameTime)
{
MouseState mouse = Mouse.GetState();
IsMouseVisible = true;
switch (CurrentGameState)
{
case GameState.MainMenu:
if (btnPlay.isClicked == true) CurrentGameState = GameState.Playing;
btnPlay.Update(mouse);
if (btnExit.isClicked == true) CurrentGameState = GameState.Help;
btnExit.Update(mouse);
if (btnExit.isClicked == true) CurrentGameState = GameState.Options;
btnExit.Update(mouse);
if (btnExit.isClicked == true) CurrentGameState = GameState.Exit;
btnExit.Update(mouse);
break;
case GameState.Playing:
timer += (float)gameTime.ElapsedGameTime.TotalSeconds;
if (timer >= dropInterval)
{
int yPos = random.Next(GraphicsDevice.Viewport.Height - 50);
enemyList.Add(new EnemySprite(enemyTexture, new Vector2(GraphicsDevice.Viewport.Width + 100, yPos)));
timer = 0f;
}
HandleCollision();
HandleMovingEnemy();
MouseState curMouse = Mouse.GetState();
Vector2 mouseLoc = new Vector2(curMouse.X, curMouse.Y);
Vector2 direction = mouseLoc - Position;
spriteRectangle = new Rectangle((int)Position.X, (int)Position.Y,
player.Texture.Width, player.Texture.Height);
Position = spriteVelocity + Position;
spriteOrigin = new Vector2(spriteRectangle.Width / 2, spriteRectangle.Height / 2);
Distance.X = mouse.X - Position.X;
Distance.Y = mouse.Y - Position.Y;
rotation = (float)Math.Atan2(Distance.Y, Distance.X); //calculates the rotation(trigonometry)
//angle = (float)(Math.Atan2(direction.Y, direction.X));
KeyboardState keyState = Keyboard.GetState();
if (keyState.IsKeyDown(Keys.A))
Position.X -= 2;
if (keyState.IsKeyDown(Keys.D))
Position.X += 2;
if (keyState.IsKeyDown(Keys.W))
Position.Y -= 2;
if (keyState.IsKeyDown(Keys.S))
Position.Y += 2;
//right and left edge detection
if (Position.X < 0)
Position = new Vector2(0, Position.Y);
int rightEdge = GraphicsDevice.Viewport.Width - player.Texture.Width;
if (Position.X > rightEdge)
Position = new Vector2(rightEdge, Position.Y);
//bottom and top edge detection
if (Position.Y < 0)
Position = new Vector2(Position.X, 0);
int bottomEdge = GraphicsDevice.Viewport.Height - player.Texture.Height;
if (Position.Y > bottomEdge)
Position = new Vector2(Position.X, bottomEdge);
if (!paused)
{
if (Keyboard.GetState().IsKeyDown(Keys.Escape))
{
paused = true;
btnPlay.isClicked = false; //so that everytime its paused I can pause it again
}
enemy.Update();
}
else if(paused)
{
if (btnPlay.isClicked)
{
paused = false;
speed = 4;
}
if (btnExit.isClicked)
Exit();
btnPlay.Update(mouse);
btnExit.Update(mouse);
}
if (Keyboard.GetState().IsKeyDown(Keys.C))
{
spriteVelocity.X = (float)Math.Cos(rotation) * tangentialVelocity;
spriteVelocity.Y = (float)Math.Sin(rotation) * tangentialVelocity;
}
else if (spriteVelocity != Vector2.Zero)
{
float i = spriteVelocity.X;
float j = spriteVelocity.Y;
spriteVelocity.X = i -= friction * i;
spriteVelocity.Y = j -= friction * j;
}
if (Keyboard.GetState().IsKeyDown(Keys.Space) && pastKey.IsKeyUp(Keys.Space))
Fire();
pastKey = Keyboard.GetState();
UpdateBullets();
break;
case GameState.Exit:
this.Exit();
break;
}
base.Update(gameTime);
}
public void UpdateBullets()
{
foreach (Bullets bullet in bulletsList)
{
bullet.position += bullet.velocity;
if(Vector2.Distance(bullet.position, Position) > 500) //finds position
bullet.isVisible = false;
}
for (int i = 0; i < bulletsList.Count; i++)
{
if (!bulletsList[i].isVisible)
{
bulletsList.RemoveAt(i);
i--;
}
}
}
//function to handle movement of enemies
private void HandleMovingEnemy()
{
List<EnemySprite> toRemove = new List<EnemySprite>();
foreach (EnemySprite e in enemyList)
{
if (e.Position.X < (-20))
{
toRemove.Add(e);
}
else
e.Position -= new Vector2(speed, 0);
}
if (toRemove.Count > 0)
{
foreach (EnemySprite e in toRemove)
{
enemyList.Remove(e);
}
}
}
private void HandleCollision()//collision
{
Sprite toRemove = null;
if (bullet != null || enemyTexture != null)
{
foreach (EnemySprite e in enemyList) //checks each enemy sprite
{
if (bullet.BoundingBox.Intersects(enemy.BoundingBox)) //checks if a sprite has intersected an enemy
{
enemyList.Remove(enemy); //removes enemy
//toRemove = enemy;
break;
}
}
}
}
public void Fire()
{
Bullets newBullet = new Bullets(Content.Load<Texture2D>("graphics/bullet"));
Bullets.BulletTexture = Content.Load<Texture2D>("graphics/bullet");
//newBullet.LoadContent(LoadContent);
newBullet.velocity = new Vector2((float)Math.Cos(rotation), (float)Math.Sin(rotation)) * 5f + spriteVelocity;
newBullet.position = Position + newBullet.velocity * 5;
newBullet.isVisible = true;
if (bulletsList.Count() < 20)
bulletsList.Add(newBullet);
}
protected override void Draw(GameTime gameTime)
{
GraphicsDevice.Clear(Color.CornflowerBlue);
spriteBatch.Begin();
switch (CurrentGameState)
{
case GameState.MainMenu:
spriteBatch.Draw(Content.Load<Texture2D>("Graphics/SeaSideDefenderMainMenu"), new Rectangle(0,0,screenWidth,screenHeight),Color.White);
btnPlay.Draw(spriteBatch);
btnExit.Draw(spriteBatch);
break;
case GameState.Playing:
spriteBatch.Draw(Content.Load<Texture2D>("Graphics/leveltest"), new Rectangle(0, 0, screenWidth, screenHeight), Color.White);
enemy = new EnemySprite();
enemy.Texture = Content.Load<Texture2D>("graphics/enemy");
enemy.Draw(spriteBatch);
spriteBatch.Draw(player.Texture, Position, null, Color.White, rotation, spriteOrigin, 1f, SpriteEffects.None, 0);
//player.Draw(spriteBatch);
foreach (EnemySprite e in enemyList)
{
e.Draw(spriteBatch);
}
foreach (Bullets bullet in bulletsList)
bullet.draw(spriteBatch);
/*for (int i; i < enemyList.Count; i++)
{
enemyList[i].Draw(spriteBatch);
}*/
if (paused)
{
speed = 0;
spriteBatch.Draw(Content.Load<Texture2D>("graphics/paused"), new Rectangle(0, 0, screenWidth, screenHeight), Color.White);
btnPlay.Draw(spriteBatch);
btnExit.Draw(spriteBatch);
}
break;
}
spriteBatch.End();
base.Draw(gameTime);
}
}
Bullets.cs
public class Bullets
{
public Texture2D texture;
public static Texture2D BulletTexture;
public Vector2 position;
public Vector2 velocity;
public Vector2 origin;
public bool isVisible;
public Rectangle BoundingBox
{
get { return new Rectangle((int)position.X, (int)position.Y, texture.Width, texture.Height); }
}
public Bullets(Texture2D newTexture)
{
texture = newTexture;
isVisible = false;
}
public void draw(SpriteBatch spriteBatch)
{
spriteBatch.Draw(texture,position,null,Color.White,0f,origin,1f, SpriteEffects.None, 0);
}
public void LoadContent(ContentManager Content)
{
BulletTexture = Content.Load<Texture2D>(#"graphics/bullet");
}
}
enemy.cs
public class EnemySprite
{
public Texture2D Texture { get; set; }
public Vector2 Position {get; set; }
public Vector2 origin;
public Vector2 velocity;
public Rectangle rectangle;
float rotation = 0f;
bool right;
float distance;
float oldDistance;
public Rectangle BoundingBox
{
get { return new Rectangle((int)Position.X, (int)Position.Y, Texture.Width, Texture.Height); } //uses enemy position and wiwdth to create bounding box
}
public EnemySprite() { }
public EnemySprite(Texture2D texture, Vector2 position)
{
Texture = texture;
Position = position;
oldDistance = distance;
}
float mouseDistance;
public void Update()
{
Position += velocity;
origin = new Vector2(Texture.Width / 2, Texture.Height / 2);
if (distance <= 0)
{
right = true;
velocity.X = 1f;
}
else if(distance <= oldDistance)
{
right = false;
velocity.X = -1f;
}
if (right) distance += 1; else distance -= 1;
MouseState mouse = Mouse.GetState();
mouseDistance = mouse.X - Position.X;
if (mouseDistance >= -200 && mouseDistance <= 200)
{
if (mouseDistance < -1)
velocity.X = -1f;
else if (mouseDistance > 1)
velocity.X = 1f;
else if (mouseDistance == 0)
velocity.X = 0f;
}
}
public void Draw(SpriteBatch spriteBatch)
{
if (Texture != null)
spriteBatch.Draw(Texture, Position, Color.White);
if (velocity.X > 0)
{
spriteBatch.Draw(Texture, Position, null, Color.White, rotation, origin, 1f, SpriteEffects.FlipHorizontally, 0f);
}
else
{
spriteBatch.Draw(Texture, Position, null, Color.White, rotation, origin, 1f, SpriteEffects.None, 0f);
}
}
}

You've not initialized the global variable Bullet anywhere in your game1.cs, therefore you would never get bullet != null as true. Whereas, you'll always get enemyTexture != null as true since you've already initialized enemyTexture in the LoadContent().
Which means you'll always enter the if block while having the Bullet variable not initialized.
Hope this will lead you to the solution.
PS: Do mark the answer as 'Accepted' if this was the most helpful one.

Need some help implementing collisions in my game, with two separate classes

What I'm trying to do is to draw rectangles behind the background and make essentially collision detection. What I'm not sure however is how exactly I can implement that. I thought about making it so that as the sprite approached these rectangles, their speed would get slower and slower till they stop but would that work? Sorry if I sound a bit wet behind the ears, I'm fairly new to C# and am trying to self teach. Any help would be appreciated.
So I have a CharacterSprite class (walkingsprite) all the stuff about the frames is just a walking animation sequence I implemented.
namespace walkingsprite
{
class AnimatedSprite
{
//keyboard
KeyboardState currentKBState;
KeyboardState previousKBState;
Texture2D spriteTexture;
float timer = 0f;
float interval = 200f;
int currentFrame = 0;
int spriteWidth = 32;
int spriteHeight = 48;
int spriteSpeed = 2;
Rectangle sourceRect;
Texture2D obst;
Rectangle obst1;
Obstruction obstruction1;
Vector2 position;
Vector2 origin;
public Vector2 Position
{
get { return position; }
set { position = value; }
}
public Vector2 Origin
{
get { return origin; }
set { origin = value; }
}
public Texture2D Texture
{
get { return spriteTexture; }
set { spriteTexture = value; }
}
public Rectangle SourceRect
{
get { return sourceRect; }
set { sourceRect = value; }
}
public int SpriteSpeed
{
get { return spriteSpeed; }
set { spriteSpeed = value; }
}
public AnimatedSprite(Texture2D texture, int currentFrame, int spriteWidth, int spriteHeight)
{
this.spriteTexture = texture;
this.currentFrame = currentFrame;
this.spriteWidth = spriteWidth;
this.spriteHeight = spriteHeight;
}
public void HandleSpriteMovement(GameTime gameTime)
{
previousKBState = currentKBState;
currentKBState = Keyboard.GetState();
sourceRect = new Rectangle(currentFrame * spriteWidth, 0, spriteWidth, spriteHeight);
////////////////////////////////////////////////////////////////////
if (currentKBState.GetPressedKeys().Length == 0)
{
if (currentFrame > 0 && currentFrame < 4)
{
currentFrame = 0;
}
if (currentFrame > 4 && currentFrame < 8)
{
currentFrame = 4;
}
if (currentFrame > 8 && currentFrame < 12)
{
currentFrame = 8;
}
if (currentFrame > 12 && currentFrame < 16)
{
currentFrame = 12;
}
}
////////////////////////////////////////////////////////////////////
//sprintin
if (currentKBState.IsKeyDown(Keys.Space))
{
spriteSpeed = 2;
interval = 100;
}
else
{
spriteSpeed = 1;
interval = 200;
}
///////////////////////////////////////////////
if (currentKBState.IsKeyDown(Keys.Down) == true)
{
AnimateDown(gameTime);
if (position.Y < 575)
{
position.Y += spriteSpeed;
}
}
////////////////////////////////////////////////////
if (currentKBState.IsKeyDown(Keys.Up) == true)
{
AnimateUp(gameTime);
if (position.Y > 25)
{
position.Y -= spriteSpeed;
}
}
//////////////////////////////////////////////////////////
if (currentKBState.IsKeyDown(Keys.Right) == true)
{
AnimateRight(gameTime);
if (position.X < 780)
{
position.X += spriteSpeed;
}
}
////////////////////////////////////////////////////////////////////
if (currentKBState.IsKeyDown(Keys.Left) == true)
{
AnimateLeft(gameTime);
if (position.X > 0)
{
position.X -= spriteSpeed;
}
}
origin = new Vector2(sourceRect.Width / 2, sourceRect.Height / 2);
}
////////////////////////////////////////////////////////////////////
public void AnimateRight(GameTime gameTime)
{
if (currentKBState != previousKBState)
{
currentFrame = 9;
}
timer += (float)gameTime.ElapsedGameTime.TotalMilliseconds;
if(timer > interval)
{
currentFrame++;
if(currentFrame > 11)
{
currentFrame = 8;
}
timer = 0f;
}
}
////////////////////////////////////////////////////////////////////
public void AnimateUp(GameTime gameTime)
{
if (currentKBState != previousKBState)
{
currentFrame = 13;
}
timer += (float)gameTime.ElapsedGameTime.TotalMilliseconds;
if (timer > interval)
{
currentFrame++;
if (currentFrame > 15)
{
currentFrame = 12;
}
timer = 0f;
}
}
//////////////////////////////////////////
public void AnimateDown(GameTime gameTime)
{
if (currentKBState != previousKBState)
{
currentFrame = 1;
}
timer += (float)gameTime.ElapsedGameTime.TotalMilliseconds;
if (timer > interval)
{
currentFrame++;
if (currentFrame > 3)
{
currentFrame = 0;
}
timer = 0f;
}
}
////////////////////////////////////////////////////
public void AnimateLeft(GameTime gameTime)
{
if (currentKBState != previousKBState)
{
currentFrame = 5;
}
timer += (float)gameTime.ElapsedGameTime.TotalMilliseconds;
if (timer > interval)
{
currentFrame++;
if (currentFrame > 7)
{
currentFrame = 4;
}
timer = 0f;
}
}
}
}
And I have an obstruction class.
namespace walkingsprite
{
class Obstruction
{
Texture2D obst;
Rectangle obstRec1;
public Rectangle ObstRec1
{
get { return obstRec1; }
set { obstRec1 = value; }
}
public Texture2D Obst
{
get { return obst; }
set { obst = value; }
}
public Obstruction(Texture2D texture, Rectangle rec)
{
this.obstRec1 = rec;
this.obst = texture;
}
}
}

XNA already have a Rectangle class with a method to return if a rectangle collide with another rectangle.
An exemple:
Rectangle rec1 = new Rectangle(0, 0, 10, 10);
Rectangle rec2 = new Rectangle(5, 5, 10, 10);
rec1.Intersects(rec2); //Return true if a rectangle intersects another one
What people normally do, is a List of Rectangle and test one by one to know if they collide, or they implements a QuadTree but that is a bit more difficult in the beginning.
An exemple of a List of Rectangle:
List<Rectangle> allObjects = new List<Rectangle>();
Rectangle rec1 = new Rectangle(0, 0, 10, 10);
Rectangle rec2 = new Rectangle(10, 15, 10, 10);
Rectangle mainCharRec = new Rectangle(10, 20, 10, 10);
allObjects.Add(rec1);
allObjects.Add(rec2);
To test if main character rectangle intersects some other rectangles you can do a method with a foreach like this:
foreach (Rectangle rec in allObjects)
if(mainCharRec.Intersects(rec))
return true;
return false;
About getting slower, I think you could have a rectangle to the object and another to the "close region", and when the character enter in the region you slow his speed by the distance you give to the region, for example, if you have a rectangle with 10 pixels larger for each side, when character collides with larger rectangle he loses spriteSpeed/10 for step, until he stops. When the value is too much low, it turn 0:
if (spriteSpeed < 0.5)
spriteSpeed = 0;
else
spriteSpeed -= spriteSpeed/10;