Question

我对C＃和XNA很陌生......对于一般的编程来说也是新手。

所以，作为一项任务，我需要使用xna制作乒乓球游戏。

我做得很好，直到我意识到球在屏幕底部像疯了一样弹跳，原因是我无法识别。

以下是我的代码

using System;
using System.Collections.Generic;
using System.Linq;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Audio;
using Microsoft.Xna.Framework.Content;
using Microsoft.Xna.Framework.GamerServices;
using Microsoft.Xna.Framework.Graphics;
using Microsoft.Xna.Framework.Input;
using Microsoft.Xna.Framework.Media;


namespace PongGame
{
public class Game1 : Microsoft.Xna.Framework.Game
{
    SpriteFont score;

    GraphicsDeviceManager graphics;
    SpriteBatch spriteBatch;

    Texture2D leftPaddle;
    Texture2D rightPaddle;
    Texture2D centerLine;

    private Texture2D ball;
    private Vector2 leftPaddlePosition = new Vector2();
    private Vector2 rightPaddlePosition = new Vector2();
    private Vector2 centerLinePosition = new Vector2();
    private Vector2 ballPosition = new Vector2();
    private Vector2 ballVelocity = new Vector2();
    private int WIDTH, HEIGHT;
    private int scoreOne=0;
    private int scoreTwo=0;
    private int round = 1;

    public Game1()
    {
        graphics = new GraphicsDeviceManager(this);
        Content.RootDirectory = "Content";
    }

    protected override void Initialize()
    {
        WIDTH = GraphicsDevice.Viewport.Width;
        HEIGHT = GraphicsDevice.Viewport.Height;
        leftPaddlePosition = new Vector2(0, (HEIGHT / 2)-40);
        rightPaddlePosition = new Vector2(WIDTH-30, (HEIGHT / 2)-40);
        centerLinePosition = new Vector2(WIDTH / 2, 0);
        ballPosition = new Vector2((WIDTH / 2)-15, (HEIGHT / 2)-15);

        base.Initialize();
    }


    protected override void LoadContent()
    {

        spriteBatch = new SpriteBatch(GraphicsDevice);

        leftPaddle = new Texture2D(GraphicsDevice, 1, 1);
        leftPaddle.SetData(new[] { Color.White });
        rightPaddle = new Texture2D(GraphicsDevice, 1, 1);
        rightPaddle.SetData(new[] { Color.White });
        centerLine = new Texture2D(GraphicsDevice, 1, 1);
        centerLine.SetData(new[] { Color.White });

        score = Content.Load<SpriteFont>("score1");

        ball = Content.Load<Texture2D>("ball2");

    }

    protected override void UnloadContent()
    {

    }

    protected override void Update(GameTime gameTime)
    {

        if (GamePad.GetState(PlayerIndex.One).Buttons.Back == ButtonState.Pressed)
            this.Exit();


        if (round % 2 != 0)
        //when the round is an odd numbered round,
        {
            ballVelocity = new Vector2(4f, 4f);
        }
        else if (round % 2 == 0)
        {
            ballVelocity = new Vector2(-4f, 4f);
        }


        KeyboardState key;

        key = Keyboard.GetState();

        if (key.IsKeyDown(Keys.W))
        {
            leftPaddlePosition.Y -= 5f;

        }

        if (key.IsKeyDown(Keys.S))
        {
            leftPaddlePosition.Y += 5f;
        }

        if (key.IsKeyDown(Keys.Up))
        {
            rightPaddlePosition.Y -= 5f;
        }

        if (key.IsKeyDown(Keys.Down))
        {
            rightPaddlePosition.Y += 5f;
        }

        //Left paddle manipulation
        if (leftPaddlePosition.Y < 0)
        {
            leftPaddlePosition.Y = 0;
        }
        if (leftPaddlePosition.Y > HEIGHT-80)
        {
            leftPaddlePosition.Y = HEIGHT-80;
        }

        //Right paddle manipulation
        if (rightPaddlePosition.Y < 0)
        {
            rightPaddlePosition.Y = 0;     
        }

        if (rightPaddlePosition.Y > HEIGHT - 80)
        {
            rightPaddlePosition.Y = HEIGHT - 80;
        }

        //Making sure that the ball stays within the window
        if (ballPosition.Y >= HEIGHT - 30)
        {
            ballVelocity.Y *= -1;
        }
        if (ballPosition.Y <= 0)
        {
            ballVelocity.Y *= -1;
        }

        //Checking if the ball goes over the left gutter
        if (ballPosition.X < 29.9f)
        {
            ballPosition.X = 29.9f;
            ballVelocity = new Vector2(0, 0);
            scoreTwo++; 
            round++;
            Initialize();
        }
        //Checking if the ball goes over the right gutter
        if (ballPosition.X > WIDTH - 29.9f-29.9f)
        {
            ballPosition.X = WIDTH - 29.9f-29.9f;
            ballVelocity = new Vector2(0, 0);
            scoreOne++;
            round++;
            Initialize();
        }

        ballPosition.X += ballVelocity.X;
        ballPosition.Y += ballVelocity.Y;
        base.Update(gameTime);
    }

    protected override void Draw(GameTime gameTime)
    {
        GraphicsDevice.Clear(Color.Black);

        spriteBatch.Begin();
        spriteBatch.Draw(ball, ballPosition, Color.White);
        spriteBatch.Draw(leftPaddle, leftPaddlePosition, null, Color.White, 0f, Vector2.Zero, new Vector2(30f, 80f), SpriteEffects.None, 0f);
        spriteBatch.Draw(rightPaddle, rightPaddlePosition, null, Color.White, 0f, Vector2.Zero, new Vector2(30f, 80f), SpriteEffects.None, 0f);
        spriteBatch.Draw(centerLine, centerLinePosition, null, Color.White, 0f, Vector2.Zero, new Vector2(1f, HEIGHT), SpriteEffects.None, 0f);

        spriteBatch.DrawString(score, System.Convert.ToString(scoreOne), new Vector2(WIDTH/4-10, 10f), Color.White);
        spriteBatch.DrawString(score, System.Convert.ToString(scoreTwo), new Vector2((WIDTH/4)*3-10, 10f), Color.White);
        spriteBatch.End();

        base.Draw(gameTime);
    } 
  }
}

我知道这里发布的代码很长，但由于我不知道问题出在哪里，我认为最好问你们。

我还将游戏上传到了一个Dropbox帐户。 download link on dropbox

Answer 1

如果没有实际运行代码，我无法分辨，但是不是在这里为你编写代码。

如果是我，我会在这里看一下（看起来最明显的嫌疑人一眼）...

//Making sure that the ball stays within the window
if (ballPosition.Y >= HEIGHT - 30)
{
    ballVelocity.Y *= -1;
}
if (ballPosition.Y <= 0)
{
    ballVelocity.Y *= -1;
}

Answer 2

你应该将速度向量乘以最后一帧除以某个速度常数（大约200）的毫秒数。这个时间包含在updatemethond的参数gameTime中。

乒乓球比赛：球像疯了似的反弹

2 个答案: