如何使用libgdx contactlistener
我刚刚开始使用Libgdx的Box2d引擎，但我根本不明白何时应该调用Contactlistener的方法。 一方面是“开始接触”，另一方面是“结束接触”。 我应该在哪里打电话给他们，以获得某个夹具接触他人的数量？ 我如何实现Contactlistener ？ 教程中的重定向将回答我的问题。 搜索谷歌时我没有找到任何东西。 这个对我有很大帮助，但是它是为C ++编写的，并没有将实现引入主游戏圈。 谢谢我帮忙;）
这是libgdx的一个简短示例。 它显示了如何创建ContactListener以显示在建立和断开联系人时涉及哪些灯具。 它还显示了world.getContactList（）的使用，它将返回物理步骤后仍然存在的联系人列表。 这可能会错过在物理步骤过程中产生和破坏的接触。 如果您对这些感兴趣，那么您将需要实现一个ContactListener ，使用beginContact（）来检测何时建立联系，并使用endContact（）来检测它们何时被破坏。
package hacks; import com.badlogic.gdx.Gdx; import com.badlogic.gdx.backends.lwjgl.LwjglApplication; import com.badlogic.gdx.backends.lwjgl.LwjglApplicationConfiguration; import com.badlogic.gdx.graphics.GL10; import com.badlogic.gdx.graphics.OrthographicCamera; import com.badlogic.gdx.math.MathUtils; import com.badlogic.gdx.math.Vector2; import com.badlogic.gdx.physics.box2d.Body; import com.badlogic.gdx.physics.box2d.BodyDef; import com.badlogic.gdx.physics.box2d.BodyDef.BodyType; import com.badlogic.gdx.physics.box2d.Box2DDebugRenderer; import com.badlogic.gdx.physics.box2d.Contact; import com.badlogic.gdx.physics.box2d.ContactImpulse; import com.badlogic.gdx.physics.box2d.ContactListener; import com.badlogic.gdx.physics.box2d.Fixture; import com.badlogic.gdx.physics.box2d.FixtureDef; import com.badlogic.gdx.physics.box2d.Manifold; import com.badlogic.gdx.physics.box2d.PolygonShape; import com.badlogic.gdx.physics.box2d.World; public class Box2DDemoMain extends com.badlogic.gdx.Game { private static final float SCALING = 0.1f; private Box2DDebugRenderer debugRenderer; private OrthographicCamera camera; private World world; @Override public void create() { debugRenderer = new Box2DDebugRenderer(); camera = new OrthographicCamera(); createWorld(); createCollisionListener(); createGround(); createBox(); } private void createWorld() { Vector2 gravity = new Vector2(0, -10); world = new World(gravity, true); } private void createCollisionListener() { world.setContactListener(new ContactListener() { @Override public void beginContact(Contact contact) { Fixture fixtureA = contact.getFixtureA(); Fixture fixtureB = contact.getFixtureB(); Gdx.app.log("beginContact", "between " + fixtureA.toString() + " and " + fixtureB.toString()); } @Override public void endContact(Contact contact) { Fixture fixtureA = contact.getFixtureA(); Fixture fixtureB = contact.getFixtureB(); Gdx.app.log("endContact", "between " + fixtureA.toString() + " and " + fixtureB.toString()); } @Override public void preSolve(Contact contact, Manifold oldManifold) { } @Override public void postSolve(Contact contact, ContactImpulse impulse) { } }); } private void createGround() { PolygonShape groundShape = new PolygonShape(); groundShape.setAsBox(50, 1); BodyDef groundBodyDef = new BodyDef(); groundBodyDef.type = BodyType.StaticBody; groundBodyDef.position.set(0, -20); Body groundBody = world.createBody(groundBodyDef); FixtureDef fixtureDef = new FixtureDef(); fixtureDef.shape = groundShape; groundBody.createFixture(fixtureDef); groundShape.dispose(); } private void createBox() { PolygonShape boxShape = new PolygonShape(); boxShape.setAsBox(1, 1); BodyDef boxBodyDef = new BodyDef(); boxBodyDef.position.set(0, 20); boxBodyDef.angle = MathUtils.PI / 32; boxBodyDef.type = BodyType.DynamicBody; boxBodyDef.fixedRotation = false; Body boxBody = world.createBody(boxBodyDef); FixtureDef boxFixtureDef = new FixtureDef(); boxFixtureDef.shape = boxShape; boxFixtureDef.restitution = 0.75f; boxFixtureDef.density = 2.0f; boxBody.createFixture(boxFixtureDef); boxShape.dispose(); } @Override public void resize(int width, int height) { super.resize(width, height); float cameraWidth = Gdx.graphics.getWidth() * SCALING; float cameraHeight = Gdx.graphics.getHeight() * SCALING; camera.setToOrtho(false, cameraWidth, cameraHeight); camera.position.set(0, 0, 0); } @Override public void render() { super.render(); world.step(Gdx.graphics.getDeltaTime(), 8, 3); int numContacts = world.getContactCount(); if (numContacts > 0) { Gdx.app.log("contact", "start of contact list"); for (Contact contact : world.getContactList()) { Fixture fixtureA = contact.getFixtureA(); Fixture fixtureB = contact.getFixtureB(); Gdx.app.log("contact", "between " + fixtureA.toString() + " and " + fixtureB.toString()); } Gdx.app.log("contact", "end of contact list"); } Gdx.gl.glClearColor(0.0f, 0.0f, 0.0f, 1.0f); Gdx.gl.glClear(GL10.GL_COLOR_BUFFER_BIT); camera.update(); debugRenderer.render(world, camera.combined); } public static void main(String[] args) { LwjglApplicationConfiguration config = new LwjglApplicationConfiguration(); config.title = Box2DDemoMain.class.getName(); config.width = 800; config.height = 480; config.fullscreen = false; config.useGL20 = true; config.useCPUSynch = true; config.forceExit = true; config.vSyncEnabled = true; new LwjglApplication(new Box2DDemoMain(), config); } } 你不必在任何地方调用这些方法。 只需创建一个类并在其中实现ContactListener。 现在在你的代码中只使用world.setContactListener（ContactListener listener）。
每当您的世界发生碰撞时，将调用所有4种方法。 您将获得2个碰撞体的fixtureA和fixtureB