发生碰撞时，如何仅以阵列形式完全删除一个Body？ Libgdx

Question

我正在用Libgdx编写游戏。 在我的游戏中，我同时创造了5枚火箭（使用Array）和一个Bird（玩家）。 我使用ContactListener来检测火箭和Bird之间的碰撞，如下所示：

if ((BodyUtils.bodyIsBird(a) && BodyUtils.bodyIsBoom(b))
                || (BodyUtils.bodyIsBird(b) && BodyUtils.bodyIsBoom(a))) {
               explosion_sound.play();
               removeRocket();
     }

发生碰撞时，我只想移除五分之一的火箭，那一枚确实与我的伯德发生碰撞。 我在removeRocket（）中编写了这样的代码，但是它删除了所有5枚火箭，但我不希望这样：

    Array<Body> bodies = new Array<Body>(world.getBodyCount());
    world.getBodies(bodies);
    for (Body body : bodies) {
        if (BodyUtils.bodyIsBoom(body)) {
            world.destroyBody (body);
          }
        }
    }

请帮我！

Answer 1

有了这个循环：

Array<Body> bodies = new Array<Body>(world.getBodyCount());
    world.getBodies(bodies);
    for (Body body : bodies) {
        if (BodyUtils.bodyIsBoom(body)) {
            world.destroyBody (body);
          }
        }
    }

您遍历世界中的所有物体并删除所有火箭物体（BodyUtils.bodyIsBoom（body）评估为true）。

您永远不会指定您实际要销毁的尸体！

只需将参数添加到removeRocket（或removeBody）方法中即可指定要删除的主体，如下所示：

// In your contact listener
if (BodyUtils.bodyIsBird(a) && BodyUtils.bodyIsBoom(b))
{
    explosion_sound.play();
    removeBody(b);
}
if (BodyUtils.bodyIsBird(b) && BodyUtils.bodyIsBoom(a))
{
    explosion_sound.play();
    removeBody(a);
}

private final Array<Body> toBeRemovedBodies = new Array<Body>();

public void removeBody(Body body)
{
    toBeRemovedBodies.add(body);
}

// After you stepped you world
for(Body body : toBeRemovedBodies)
    world.destroyBody(body);

旁注：如您所见，我不会在removeBody方法上破坏物体，因为它是在当前世界处于仿真状态时调用的，并且在此期间不得破坏物体，因为它可能导致不可预测的行为。

编辑：

由于在再次阅读您的问题后，我不能完全确定自己是否完全理解它，因此，我创建了一个小而完整的示例来说明如何在接触时破坏尸体：

import com.badlogic.gdx.ApplicationAdapter;
import com.badlogic.gdx.Gdx;
import com.badlogic.gdx.graphics.GL20;
import com.badlogic.gdx.graphics.OrthographicCamera;
import com.badlogic.gdx.math.Vector2;
import com.badlogic.gdx.physics.box2d.*;
import com.badlogic.gdx.utils.Array;

public class TestGame extends ApplicationAdapter
{
    enum BodyData
    {
        BIRD, ROCKET;
    }

    class MyContactListener implements ContactListener
    {

        @Override
        public void beginContact(Contact contact)
        {
            Body a = contact.getFixtureA().getBody();
            Body b = contact.getFixtureB().getBody();

            if (a.getUserData() == BodyData.BIRD
                    && b.getUserData() == BodyData.ROCKET)
            {
                // play sound
                toBeDeletedBodies.add(b);
            }
            if (b.getUserData() == BodyData.BIRD
                    && a.getUserData() == BodyData.ROCKET)
            {
                // play sound
                toBeDeletedBodies.add(a);
            }
        }

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

        }

        @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

        }

    }

    Array<Body>         toBeDeletedBodies   = new Array<>();
    Array<Body>         allBodies           = new Array<>();

    World               world;

    Box2DDebugRenderer  renderer;

    OrthographicCamera  camera;

    @Override
    public void create()
    {
        world = new World(new Vector2(0, -1), true);

        BodyDef bodyDefBird = new BodyDef();
        bodyDefBird.position.set(0, 0.1f);
        bodyDefBird.type = BodyDef.BodyType.DynamicBody;

        BodyDef bodyDefRocket1 = new BodyDef();
        bodyDefRocket1.position.set(0, 0.5f);
        bodyDefRocket1.type = BodyDef.BodyType.DynamicBody;

        BodyDef bodyDefRocket2 = new BodyDef();
        bodyDefRocket2.position.set(0.1f, 0.8f);
        bodyDefRocket2.type = BodyDef.BodyType.DynamicBody;

        FixtureDef circleFixture = new FixtureDef();
        circleFixture.shape = new CircleShape();
        ((CircleShape) circleFixture.shape).setRadius(0.02f);

        FixtureDef rocketFixture = new FixtureDef();
        rocketFixture.shape = new PolygonShape();
        ((PolygonShape) rocketFixture.shape).set(new float[]
        { 0, 0, 0.01f, 0, 0.01f, 0.05f, 0, 0.05f, 0, 0 });

        BodyDef bodyDefFloor = new BodyDef();
        bodyDefFloor.position.set(-100, 0);
        bodyDefFloor.type = BodyDef.BodyType.StaticBody;

        FixtureDef lineFixture = new FixtureDef();
        lineFixture.shape = new EdgeShape();
        ((EdgeShape) lineFixture.shape).set(Vector2.Zero, new Vector2(200, 0));

        Body floor = world.createBody(bodyDefFloor);
        floor.createFixture(lineFixture);

        Body bird = world.createBody(bodyDefBird);
        bird.createFixture(circleFixture);
        bird.setUserData(BodyData.BIRD);

        Body rocket1 = world.createBody(bodyDefRocket1);
        rocket1.createFixture(rocketFixture);
        rocket1.setUserData(BodyData.ROCKET);

        Body rocket2 = world.createBody(bodyDefRocket2);
        rocket2.createFixture(rocketFixture);
        rocket2.setUserData(BodyData.ROCKET);

        renderer = new Box2DDebugRenderer();

        camera = new OrthographicCamera();

        world.setContactListener(new MyContactListener());

        rocketFixture.shape.dispose();
        circleFixture.shape.dispose();
        lineFixture.shape.dispose();
    }

    @Override
    public void render()
    {
        Gdx.gl.glClearColor(1, 0, 0, 1);
        Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);

        world.step(1 / 60f, 8, 3);

        renderer.render(world, camera.combined);

        for (Body body : toBeDeletedBodies)
        {
            world.destroyBody(body);
        }

        toBeDeletedBodies.clear();
    }

    @Override
    public void dispose()
    {
        renderer.dispose();
        world.dispose();
    }
}

运行此示例时，您会看到地板上有一个圆圈（鸟）和两个矩形（火箭）掉落的情况。 一个矩形碰到圆并因此被破坏，另一个矩形不被破坏。

发生碰撞时，如何仅以阵列形式完全删除一个Body？ Libgdx

问题描述

1 个解决方案

解决方案1
2 已采纳 2015-10-11 11:16:13

发生碰撞时，如何仅以阵列形式完全删除一个Body？ Libgdx

问题描述

1 个解决方案

解决方案1 2 已采纳 2015-10-11 11:16:13

解决方案1
2 已采纳 2015-10-11 11:16:13