我正在编写一个用于slick2d + java中的碰撞检测的算法，我将最终在我将要制作的平台游戏中使用它。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，该算法有很多问题，我无法弄清楚如何修复。首先，有时玩家从矩形移动得太远，所以看起来它正在反弹。其次，玩家有时能够在矩形内部移动一个小而明显的数量。最后，如果我有时增加速度，玩家可以一直通过矩形。这是一个相当模糊的问题，但我真的需要帮助找出问题所在。任何想法都将非常感激。如果安装了Slick2D，源代码应该编译没有任何问题。
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);
}
}
}
答案 0 :(得分：2)
高速度和玩家通过矩形的问题与你对碰撞数据进行采样的频率有关。
让我们假设我真的很笨，而且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，那么它的方向就是1平方米。如果我在物体距离广场7米处检查碰撞，然后一秒钟后，我会完全错过物体穿过广场。
许多碰撞检测库处理这个问题的方法是，它们比常规对象更频繁地检查快速移动的对象。当这种情况发生时，你的玩家会“快速”移动？
答案 1 :(得分：2)
所以只需转动你的问题：在移动前检查，而不是在移动之后检查。如果玩家将落入矩形，则不允许他。
这里出现了问题中更重要的部分：“只是触摸表面”有多远（并且实际上取决于你如何进行碰撞检测;如果你正在进行边界框碰撞，它会转化为计算，如果你正在进行像素完美的碰撞，你可能需要测试一些假设情况。）
由于这种情况一直在发生，尽量避免不必要的工作（为什么逐像素测试，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“矩形足够”的对象边界框~~像素pirfect ...）
欢迎来到编程世界，它更多的是解决问题，而不是打击“画一个尖顶，将它按x像素和10个”语句移动到一起; - ）