Getting Acces to Other Classes Variables

问题

I'm working on a pong game, since i'm new at programming, i don't know how to get acess to another class variable. I have seperate classes, green and blue paddles, a ball, and game1.cs.

I control the ball movement with bool movingUp, movingLeft;

It bounces off the borders of the screen, but i don't know how to make it work with the paddles. Basically, how do i check the position of the paddle, and make so when the ball touches the paddle, it bounces off? I mean, how to detect the collision?

public class Ball
{
    ParticleEngine particleEngine;
    GraphicsDeviceManager graphics;
    Texture2D texture;
    Vector2 position;
    Boolean movingUp, movingLeft;
    Vector2 origin;

    public Ball()
    {
        position = new Vector2(800 / 2, 330);
    }

    public void LoadContent(ContentManager Content)
    {
        texture = Content.Load<Texture2D>("ball");
        movingLeft = true;
        //Particle Engine
        List<Texture2D> textures = new List<Texture2D>();
        textures.Add(Content.Load<Texture2D>("pixel"));
        particleEngine = new ParticleEngine(textures, new Vector2(400, 240));
    }

    public void Update(GameTime gameTime)
    {
        float speed = 2.5f;

        //Physics
        if (movingUp)
        {
            position.Y -= 3;
        }

        if (movingLeft)
        {
            position.X -= 3;
        }

        if (!movingUp)
        {
            position.Y += 3;
        }

        if (!movingLeft)
        {
            position.X += 3;
        }

        if (position.X <= 0 && movingLeft) movingLeft = false;
        if (position.Y <= 85 && movingUp) movingUp = false;

        if (position.X >= 800 - texture.Width && !movingLeft) movingLeft = true;
        if (position.Y >= 500 - texture.Height && !movingUp) movingUp = true;

        origin = new Vector2(position.X + texture.Width / 2, position.Y + texture.Height / 2);

        //Particles
        particleEngine.EmitterLocation = new Vector2(origin.X, origin.Y);
        particleEngine.Update();
    }

    public void Draw(SpriteBatch spriteBatch)
    {
        particleEngine.Draw(spriteBatch);
        spriteBatch.Draw(texture, position, Color.White);
    }

}

One of the paddle classes (they look the same exept the name and movement keys):

public class GreenPaddle
{
    Texture2D texture;
    Vector2 position;
    float speed = 2f;
    public GreenPaddle()
    {
       position = new Vector2(10, 230);
    }
    public void LoadContent(ContentManager Content)
    {
        texture = Content.Load<Texture2D>("greenpaddle");
    }
    public void Update(GameTime gameTime)
    {
        KeyboardState keyState = Keyboard.GetState();
        //Check If Keys Are Pressed // Movement
        if (keyState.IsKeyDown(Keys.W))
            position.Y -= speed;
        if (keyState.IsKeyDown(Keys.S))
            position.Y += speed;
        //Check Border
        if (position.Y < 87)
        {
            position.Y = 87;
        }
        if (position.Y > 396)
        {
            position.Y = 396;
        }
     }
     public void Draw(SpriteBatch spriteBatch)
     {
        spriteBatch.Draw(texture, position, Color.White);
     }
}

Thanks in advance, i really wish to learn things like this :D

回答1:

Declare the variables you want to access as public, or create get methods.

For public variables you would do:

public Vector2 Position;

And to access it, you would call:

Ball ball;
ball.Position

For get method implement:

public Vector2 getPosition()
{
    return Position;
}

And you would call that method to get the position.

来源：https://stackoverflow.com/questions/17883303/getting-acces-to-other-classes-variables