1

我正在 slick2d + java 中编写一个碰撞检测算法，我最终将在我将制作的平台游戏中使用它。该算法的工作原理是检测玩家与矩形重叠的程度，然后通过重叠将玩家移出矩形。问题是，该算法有很多我不知道如何解决的问题。首先，有时玩家离开矩形太远，所以看起来它正在反弹。其次，有时玩家能够在矩形内移动一个很小但很明显的量。最后，如果我提高速度，有时玩家可以一直穿过矩形。这是一个相当模糊的问题，但我真的需要一些帮助来找出问题所在。任何想法都将不胜感激。

算法：

public void Collision(Polygon player, Polygon poly, Vector2f translation){
    Vector2f magnitude = new Vector2f();

    //Find the vectre of each object
    Vector2f p1Centre = new Vector2f(player.getX() + (player.getWidth()/2), player.getY() + (player.getHeight()/2));
    Vector2f p2Centre = new Vector2f(poly.getX() + (poly.getWidth()/2), poly.getY() + (poly.getHeight()/2));

    //Calculate the distance between the two
    Vector2f distance = new Vector2f(p1Centre);
    distance.sub(p2Centre);

    //Get the absolute distance
    Vector2f absDistance = new Vector2f(distance.x<0 ? -distance.x : distance.x, distance.y<0 ? -distance.y : distance.y);

    //Get the combined half widths and heights of each object
    Vector2f halvedBounds = new Vector2f((player.getWidth() + poly.getWidth())/2.0f, (player.getHeight() + poly.getHeight())/2.0f);

    //If the absolute distance is less thate the halved widths heights then there is a collision
    if((absDistance.x < halvedBounds.x) && (absDistance.y < halvedBounds.y)){

        //Set the magnitude vector to the halved bounds minus the absolute distance
        magnitude.x = halvedBounds.x - absDistance.x;
        magnitude.y = halvedBounds.y - absDistance.y;

        //Only react to the lesser overlap;
        if(magnitude.x < magnitude.y){
            magnitude.x = (distance.x > 0) ? magnitude.x : -magnitude.x;
            magnitude.y = 0;
        }
        else{
            magnitude.y = (distance.y > 0) ? magnitude.y : -magnitude.y;
            magnitude.x = 0;
        }

        //Debug
        System.out.println(magnitude.x+"            "+magnitude.y);
        System.out.println(translation.x+"            "+translation.y+"\n");

        //Add the magnitude to the player position
        position.add(magnitude);
    }       
}

完整来源：

import java.util.ArrayList;

import org.newdawn.slick.AppGameContainer;
import org.newdawn.slick.BasicGame;
import org.newdawn.slick.Color;
import org.newdawn.slick.GameContainer;
import org.newdawn.slick.Graphics;
import org.newdawn.slick.Input;
import org.newdawn.slick.SlickException;
import org.newdawn.slick.geom.Polygon;
import org.newdawn.slick.geom.Vector2f;

public class TestCode extends BasicGame {

    private Vector2f position = new Vector2f(300, 300);

    private ArrayList<Polygon> solids;
    private Polygon player;

    public TestCode(String title) {
        super(title);
    }

    public static void main(String[] args) throws SlickException{
        AppGameContainer game = new AppGameContainer(new TestCode("test"));
        game.setDisplayMode(800, 600, false);
        game.start();
    }

    @Override
    public void render(GameContainer gc, Graphics g) throws SlickException {

        if(gc.isPaused()){
            g.setColor(Color.red);
            g.drawString("Paused", 90, 10);
        }else{
            g.setColor(Color.green);
            g.drawString("Playing", 90, 10);
        }

        g.setColor(Color.red);
        for(Polygon p : solids)
            g.fill(p);

        g.setColor(Color.cyan);
        g.fill(player);

    }

    @Override
    public void init(GameContainer gc) throws SlickException {      
        gc.setVSync(true);

        solids = new ArrayList<Polygon>();

        player = new Polygon(new float[]{
                50, 50,  // upper left point
                70, 50,  // upper right
                70, 90, // lower right
                50, 90   // lower left
        }); 


        for(int i=0, x=200, y=200; i<10; i++, x+=40){
            solids.add(new Polygon(new float[]{
                    x, y,  // upper left point
                    x+40, y,  // upper right
                    x+40, y+40, // lower right
                    x, y+40   // lower left
            }));    
        }

    }

    @Override
    public void update(GameContainer gc, int delta) throws SlickException {

        Input input = gc. getInput();

        Vector2f translation = new Vector2f(0, 0);

        if(input.isKeyDown(Input.KEY_UP))
            translation.y = -1f;
        if(input.isKeyDown(Input.KEY_DOWN))
            translation.y = 1f;
        if(input.isKeyDown(Input.KEY_LEFT))
            translation.x = -1f;
        if(input.isKeyDown(Input.KEY_RIGHT))
            translation.x = 1f;

        translation.normalise();
        translation.x*=2;
        translation.y*=2;

        position.add(translation);

        for(Polygon p : solids)
            Collision(player, p, translation);

        player.setLocation(position);
    }

    public void Collision(Polygon player, Polygon poly, Vector2f translation){
        Vector2f magnitude = new Vector2f();

        //Find the vectre of each object
        Vector2f p1Centre = new Vector2f(player.getX() + (player.getWidth()/2), player.getY() + (player.getHeight()/2));
        Vector2f p2Centre = new Vector2f(poly.getX() + (poly.getWidth()/2), poly.getY() + (poly.getHeight()/2));

        //Calculate the distance between the two
        Vector2f distance = new Vector2f(p1Centre);
        distance.sub(p2Centre);

        //Get the absolute distance
        Vector2f absDistance = new Vector2f(distance.x<0 ? -distance.x : distance.x, distance.y<0 ? -distance.y : distance.y);

        //Get the combined half widths and heights of each object
        Vector2f halvedBounds = new Vector2f((player.getWidth() + poly.getWidth())/2.0f, (player.getHeight() + poly.getHeight())/2.0f);

        //If the absolute distance is less thate the halved widths heights then there is a collision
        if((absDistance.x < halvedBounds.x) && (absDistance.y < halvedBounds.y)){

            //Set the magnitude vector to the halved bounds minus the absolute distance
            magnitude.x = halvedBounds.x - absDistance.x;
            magnitude.y = halvedBounds.y - absDistance.y;

            //Only react to the lesser overlap;
            if(magnitude.x < magnitude.y){
                magnitude.x = (distance.x > 0) ? magnitude.x : -magnitude.x;
                magnitude.y = 0;
            }
            else{
                magnitude.y = (distance.y > 0) ? magnitude.y : -magnitude.y;
                magnitude.x = 0;
            }

            //Debug
            System.out.println(magnitude.x+"            "+magnitude.y);
            System.out.println(translation.x+"            "+translation.y+"\n");

            //Add the magnitude to the player position
            position.add(magnitude);
        }       
    }   
}
4

2 回答 2

2

因此，只需扭转您的问题：在搬家前检查，而不是在搬家后检查。如果玩家将降落在矩形中，则不允许他。

这是您问题中更重要的部分：“仅接触表面”有多远（实际上取决于您如何进行碰撞检测；如果您正在做边界框碰撞，它会转化为计算，如果您正在做像素完美的碰撞，您可能需要测试一些假设情况）。

由于这种情况经常发生，请尽量避免不必要的工作（为什么逐个像素进行测试，间隔分割可能是更好的方法；首先进行边界框计算，然后像素完美；对于“足够矩形”的物体边界框~~像素完美.. .)

欢迎来到编程的世界，它更多的是关于解决问题，而不是把一堆“画一个尖顶，将它移动 x 像素和转到 10”语句一起拍打;-)

于 2012-05-24T08:46:20.580 回答
2

高速和通过矩形的玩家的问题与您对碰撞数据进行采样的频率有关。

假设我真的很笨，我每秒只检查一次碰撞。如果一个物体以每秒 15 米的速度移动，并且有一个 1 平方米的范围。如果我在物体距离广场 7 米时检查碰撞，然后一秒钟后，我会完全错过物体穿过广场的情况。

许多碰撞检测库处理这个问题的方式是它们比常规对象更频繁地检查快速移动的对象。发生这种情况时，您的播放器移动有多“快”？

于 2012-04-24T21:45:24.783 回答