XNA 矩形交点 [英] XNA Rectangle intersection

问题描述

我最近开始进行 XNA 开发，过去有一些(非常有限的)经验，我决定尝试制作一个 Pong 克隆，看看我能记住多少.我所知道的大部分内容都回到了我的脑海中，但我在球棒和球之间的碰撞检测方面遇到了问题.我将 3 个矩形设置为与我正在使用的精灵一起更新位置，当球矩形与蝙蝠矩形相交时，我将球的 X 速度乘以 -1.然而，这会产生一种不寻常的效果，即球在球棒周围弹跳，如此视频所示.我在这里做错了什么?

I recently started on XNA development and having some (very limited) experience with it in the past, I decided to try and make a Pong clone to see how much I could remember. Most of what I knew came back to me, but I am having problems with collision detection between the bats and the ball. I have 3 rectangles set to update position along with the sprites that I am using, and when the ball rectangle intersects with a bat rectangle, I multiply the X speed of the ball by -1. However this produces an unusual effect by which the ball bounces around the bat as shown in this video.What am I doing wrong here?

这是这个项目的代码(可怜，我知道):

Here is the code for this project (poor, I know):

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 Pong
{

public class Game1 : Microsoft.Xna.Framework.Game
{
    GraphicsDeviceManager graphics;
    SpriteBatch spriteBatch;

    System.Random generator = new Random();

    Texture2D ball;
    Texture2D bat1;
    Texture2D bat2;
    Texture2D middle;

    Vector2 midPos;
    Vector2 bat1Pos;
    Vector2 bat2Pos;
    Vector2 ballPos;
    Vector2 ballVelo;

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

    protected override void Initialize()
    {
        base.Initialize();
    }

    protected override void LoadContent()
    {
        // Create a new SpriteBatch, which can be used to draw textures.
        spriteBatch = new SpriteBatch(GraphicsDevice);

        //Load sprites
        ball = Content.Load<Texture2D>(@"sprites/pongball");
        bat1 = Content.Load<Texture2D>(@"sprites/pongbat");
        bat2 = Content.Load<Texture2D>(@"sprites/pongbat");
        middle = Content.Load<Texture2D>(@"sprites/pongmiddle");

        //Set default sprite positions
        midPos.X = (Window.ClientBounds.Width / 2) - 5;
        midPos.Y = 0;

        bat1Pos.X = 10;
        bat1Pos.Y = (Window.ClientBounds.Height/2) - 50;

        bat2Pos.X = Window.ClientBounds.Width - 20;
        bat2Pos.Y = (Window.ClientBounds.Height/2) - 50;

        ballPos.X = (Window.ClientBounds.Width / 2) - 5;
        ballPos.Y = (Window.ClientBounds.Height / 2) - 5;

        //Generate random ball velocity
        ballVelo.X = generator.Next(5,10);
        ballVelo.Y = generator.Next(4, 7);
    }

    protected override void UnloadContent()
    {

    }

    protected override void Update(GameTime gameTime)
    {


        //Update rectangle values
        Rectangle bat1Rect = new Rectangle((int)bat1Pos.X, (int)bat1Pos.Y, 10, 100);
        Rectangle bat2Rect = new Rectangle((int)bat2Pos.X, (int)bat2Pos.Y, 10, 100);
        Rectangle ballRect = new Rectangle((int)ballPos.X, (int)ballPos.Y, 10, 100);

        //Move ball
        ballPos += ballVelo;

        // Allows the game to exit
        if (GamePad.GetState(PlayerIndex.One).Buttons.Back == ButtonState.Pressed)
            this.Exit();
        if (Keyboard.GetState().IsKeyDown(Keys.Escape))
            this.Exit();

        //Bat 1 movement and restriction
        if (Keyboard.GetState().IsKeyDown(Keys.Up))
            bat1Pos.Y -= 4;

        if (Keyboard.GetState().IsKeyDown(Keys.Down))
            bat1Pos.Y += 4;

        if (bat1Pos.Y <= 0)
            bat1Pos.Y = 0;

        if (bat1Pos.Y >= Window.ClientBounds.Height - 100)
            bat1Pos.Y = Window.ClientBounds.Height - 100;


        //Bat 2 movement and restriction
        if (Keyboard.GetState().IsKeyDown(Keys.W))
            bat2Pos.Y -= 4;

        if (Keyboard.GetState().IsKeyDown(Keys.S))
            bat2Pos.Y += 4;

        if (bat2Pos.Y <= 0)
            bat2Pos.Y = 0;

        if (bat2Pos.Y >= Window.ClientBounds.Height - 100)
            bat2Pos.Y = Window.ClientBounds.Height - 100;

        //Ball movement restrictions
        if (ballPos.X <= 0)
            ballVelo.X *= -1;

        if (ballPos.Y <= 0)
            ballVelo.Y *= -1;

        if (ballPos.X >= Window.ClientBounds.Width - 5)
            ballVelo.X *= -1;

        if (ballPos.Y >= Window.ClientBounds.Height - 5)
            ballVelo.Y *= -1;


        //Collision detection between bats and ball
        if (ballRect.Intersects(bat1Rect))
        {
            ballVelo.X *= -1;
        }

        if (ballRect.Intersects(bat2Rect))
        {
            ballVelo.X *= -1;
        }

        base.Update(gameTime);
    }

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

        spriteBatch.Begin();
        spriteBatch.Draw(middle, midPos, Color.White);
        spriteBatch.Draw(bat1, bat1Pos, Color.White);
        spriteBatch.Draw(bat2, bat2Pos, Color.White);
        spriteBatch.Draw(ball, ballPos, Color.White);
        spriteBatch.End();

        base.Draw(gameTime);
    }
}
}

推荐答案

解决此问题的一种方法是对 ballRect.Intersect(barXRect)) if 语句进行以下更改:>

One way around this would be to do make the following change to your ballRect.Intersect(barXRect)) if statements:

    if (ballRect.Intersects(bat1Rect))
    {
        ballVelo.X = Math.Abs(ballVelo.X) * -1;
    }

    if (ballRect.Intersects(bat2Rect))
    {
        ballVelo.X = Math.Abs(ballVelo.X);
    }

这样左边的杆只会把球传到右边，右边的杆只会把球传到左边.我可能有错误的方法，所以最好仔细检查一下，但这只是意味着将 * -1 移动到另一个蝙蝠.

This way the left bar will only send the ball right, and the right bar will only send it left. I may have the bars around the wrong way, so it might be best to double check, but it just means moving the * -1 to the other bat.

这篇关于XNA 矩形交点的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！