联系侦听器在 Libgdx 中不起作用

Question

我正在 Libgdx 中开发一个游戏，我正在研究 2D 框中两个物体之间的碰撞检测。我使用“Contact Listener”来检测碰撞，但是当身体碰撞时没有任何反应。

这是我的代码

  public Player(World world,float x,float y,float width)
  {
   this.width=width; //IMP
   height=width*2;
   BodyDef polygon=new BodyDef();
   polygon.type=BodyType.DynamicBody;
   polygon.position.set(x,y); //

   polygon.fixedRotation=true;
   PolygonShape poly =new PolygonShape();
   poly.setAsBox(width/2,height/2); //
  //fixture defn
  polygon.position.set(5,4);
  FixtureDef polyfixture=new FixtureDef();
  polyfixture.shape=poly;

  polyfixture.friction=0.8f;  //
  polyfixture.restitution=0.1f; //
  polyfixture.density=3; //


  //creating actual body
  polybody=world.createBody(polygon);
  polybody.createFixture(polyfixture);


  polysprite=new Sprite(new Texture("img/car.jpg"));

  polysprite.setSize(2, 3); //size of mario
  polysprite.setOrigin(polysprite.getWidth()/2, polysprite.getHeight()/2);
  polybody.setUserData(polysprite);

第二个身体

   BodyDef polygons=new BodyDef();
   polygons.type=BodyType.DynamicBody;

   PolygonShape polys=new PolygonShape();
   polys.setAsBox(2,2);

   FixtureDef polyxfixture=new FixtureDef();
   polyxfixture.shape=polys;
   polyxfixture.friction=0.8f;
   polyxfixture.restitution=0.1f;
   polyxfixture.density=3;
   polybodys=world.createBody(polygons);
   polybodys.createFixture(polyxfixture);
   poly.dispose();    
   }
   @Override
    public void beginContact(Contact contact) {
// TODO Auto-generated method stub

Fixture fixtureA=contact.getFixtureA();
Fixture fixtureB=contact.getFixtureB();

if(fixtureA.getUserData() != null && fixtureA.getUserData().equals("polybody") &&
        fixtureB.getUserData() !=null && fixtureB.getUserData().equals("polybodys")){
    Gdx.app.log("Contact","1");
    System.out.println("its colliding");

}

if(fixtureB.getUserData() !=null && fixtureB.getUserData().equals("polybody") &&
        fixtureA.getUserData() !=null && fixtureA.getUserData().equals("polybodys"))
{
    System.out.println("its colliding");
}
}

我添加了 world.setContactListener(player);其中“玩家”是上述类的名称。

这是我检测碰撞的代码。当我运行代码并测试身体之间的碰撞时，什么也没有发生。我在控制台中使用“println”语句进行了测试。我不知道这里有什么问题。请帮忙。提前致谢！！

Answer 1

我认为该链接是一种做你想做的事的方法，也许它不是最好的方法，但它可以帮助另一方面我会尝试调整它以对你的示例进行编码，但如果它有效，因为不完整，并且让我有些困惑

您的代码有更改：

public Player(World world,float x,float y,float width){

   this.width = width; 
   height     =width*2;

   BodyDef polygon = new BodyDef();
   polygon.type    = BodyType.DynamicBody;

   polygon.position.set(x,y); //<-- you use position one
   polygon.fixedRotation = true;

   PolygonShape poly = new PolygonShape();
                poly.setAsBox(width/2,height/2); 

  //fixture defn

  polygon.position.set(5,4);   //<-- you use position two, twice, 
                               //this overrides the previous consider this

  FixtureDef polyfixture = new FixtureDef();
             polyfixture.shape = poly;

  polyfixture.friction    = 0.8f;  
  polyfixture.restitution = 0.1f; 
  polyfixture.density     = 3; 

  //creating actual body
  polybody = world.createBody(polygon);

  //add.setUserData("YourBody1Name");
  // polybody.createFixture(polyfixture); <-- this original code
  // change for example:
  polybody.createFixture(polyfixture).setUserData("YourBody1"); 

  polysprite = new Sprite(new Texture("img/car.jpg"));

  polysprite.setSize(2, 3); //size of mario
  polysprite.setOrigin(polysprite.getWidth()/2, polysprite.getHeight()/2);

第二个身体

   BodyDef polygons = new BodyDef();
           polygons.type = BodyType.DynamicBody;

   //you do not use it for poligons position?
   //for example:
   //polygons.position.set(yourPosX,yourPosY); 

   PolygonShape polys = new PolygonShape();
                polys.setAsBox(2,2);

   FixtureDef polyxfixture = new FixtureDef();
              polyxfixture.shape       = polys;
              polyxfixture.friction    = 0.8f;
              polyxfixture.restitution = 0.1f;
              polyxfixture.density     = 3;

   polybodys = world.createBody(polygons);

  //add.setUserData("YourBody2Name");
  // polybodys.createFixture(polyxfixture); <-- this original code
  // change for example:
   polybodys.createFixture(polyxfixture).setUserData("YourBody2"); 

   poly.dispose(); 
   //polys.dispose(); //<-- I do not see this dispose in your code. 

   }

现在在你创建世界的课堂上。复制这段代码：

private class CrearContactListener implements ContactListener {

        public CrearContactListener(){

        }
        @Override
        public void preSolve(Contact contact, Manifold oldManifold) {
            // TODO Auto-generated method stub

        }

        @Override
        public void postSolve(Contact contact, ContactImpulse impulse) {
            // TODO Auto-generated method stub

        }

        @Override
        public void endContact(Contact contact) {
            // TODO Auto-generated method stub

        }

        @Override
        public void beginContact(Contact contact) {
            // TODO Auto-generated method stub

            Fixture fixtureA = contact.getFixtureA();
            Fixture fixtureB = contact.getFixtureB();

            if(fixtureA.getUserData() != null 
               && fixtureA.getUserData().equals("YourBody1") 
               && fixtureB.getUserData() != null 
               && fixtureB.getUserData().equals("YourBody2")){

                Gdx.app.log("Contact","1");
            }

            if(fixtureB.getUserData() != null 
               && fixtureB.getUserData().equals("YourBody1")
               && fixtureA.getUserData() != null 
               && fixtureA.getUserData().equals("YourBody2")){

                Gdx.app.log("Contact","2");
            }
        }
}

注意这是一个私有类，你必须把它放在一个适合该类的位置，你不知道在哪里可以找到更多关于如何在另一个类中使用私有类的信息。

并使用此代码分配 ContactListener：

YourWorld.setContactListener(new CrearContactListener());

在身体2看什么位置，可能需要一个。

在本例中，删除 public void beginContact (Contact contact) 在你的类播放器中，原因之一是我不知道你的播放器类是否实现了 ContactListener 或者只是你把它放在那里。

我这个代码没有经过测试，但我认为它可以工作，考虑到你提到的，另一方面，为我的英语道歉，我希望你能理解我。