Java Libgdx-box2D错误
我正在做一个Box2D跳跃和跑步游戏,希望玩家在碰到钉子时死亡,但是当他碰到钉子时,我得到一个空指针异常 这是我的联系方式:Java Libgdx-box2D错误,java,nullpointerexception,libgdx,box2d,Java,Nullpointerexception,Libgdx,Box2d,我正在做一个Box2D跳跃和跑步游戏,希望玩家在碰到钉子时死亡,但是当他碰到钉子时,我得到一个空指针异常 这是我的联系方式: public class WorldContactListener implements ContactListener { Player player; @Override public void beginContact(Contact contact) { Fixture fixA = contact.getFixtureA(); Fixture
public class WorldContactListener implements ContactListener {
Player player;
@Override
public void beginContact(Contact contact) {
Fixture fixA = contact.getFixtureA();
Fixture fixB = contact.getFixtureB();
player = new Player();
int cDef = fixA.getFilterData().categoryBits | fixB.getFilterData().categoryBits;
switch (cDef) {
case HardwareRunner.PLAYER_BIT | HardwareRunner.BRICK_BIT:
case HardwareRunner.PLAYER_BIT | HardwareRunner.SPIKE_BIT:
player.die();
}
}
下面是我的球员课程的一部分:
public void definePlayer(){
bdef.position.set(32 / runner.PPM, (6 * 32) / runner.PPM);
bdef.type = BodyDef.BodyType.DynamicBody;
b2body = world.createBody(bdef);
FixtureDef fdef = new FixtureDef();
PolygonShape shape = new PolygonShape();
Vector2[] vertice = new Vector2[4];
vertice[0] = new Vector2(-13, 13).scl(1 / runner.PPM);
vertice[1] = new Vector2(13, 13).scl(1 / runner.PPM);
vertice[2] = new Vector2(13, -13).scl(1 / runner.PPM);
vertice[3] = new Vector2(-13, -13).scl(1 / runner.PPM);
shape.set(vertice);
shape.getRadius();
fdef.filter.categoryBits = HardwareRunner.PLAYER_BIT;
fdef.filter.maskBits =
HardwareRunner.GROUND_BIT |
HardwareRunner.COIN_BIT |
HardwareRunner.BRICK_BIT |
HardwareRunner.ENEMY_BIT |
HardwareRunner.SPIKE_BIT |
HardwareRunner.ENEMY_HEAD_BIT |
HardwareRunner.ITEM_BIT;
fdef.shape = shape;
fdef.friction = .1f;
b2body.createFixture(fdef).setUserData(this);
fdef.isSensor = true;
b2body.createFixture(fdef).setUserData(this);
}
public void die() {
world.destroyBody(b2body);
}
错误是:
Exception in thread "LWJGL Application" java.lang.NullPointerException
at de.tobls.hardwarerunner.Sprites.Player.die(Player.java:223)
at de.tobls.hardwarerunner.Tools.WorldContactListener.beginContact(WorldContactListener.java:27)
at com.badlogic.gdx.physics.box2d.World.beginContact(World.java:982)
at com.badlogic.gdx.physics.box2d.World.jniStep(Native Method)
at com.badlogic.gdx.physics.box2d.World.step(World.java:686)
at de.tobls.hardwarerunner.Screens.PlayScreen.update(PlayScreen.java:112)
at de.tobls.hardwarerunner.Screens.PlayScreen.render(PlayScreen.java:127)
at com.badlogic.gdx.Game.render(Game.java:46)
at de.tobls.hardwarerunner.HardwareRunner.render(HardwareRunner.java:71)
at com.badlogic.gdx.backends.lwjgl.LwjglApplication.mainLoop(LwjglApplication.java:215)
at com.badlogic.gdx.backends.lwjgl.LwjglApplication$1.run(LwjglApplication.java:120)
有人能帮我吗?问题来自这样一个事实:当你的玩家死亡时,你会在
开始接触(接触)
中毁掉他的身体。
这是box2D的一个非常经典的问题。在模拟步骤中,box2D将检查每个实体之间是否存在碰撞,但如果在模拟运行时销毁实体,则会出现此NullPointerException
要解决这个问题,可以使用布尔值,比如布尔值dead
。在您的beginContact(Contact Contact)
中,您将拥有:
switch (cDef) {
case HardwareRunner.PLAYER_BIT | HardwareRunner.BRICK_BIT:
case HardwareRunner.PLAYER_BIT | HardwareRunner.SPIKE_BIT:
player.dead = true;
}
在的render()方法中,您将检查玩家是否死亡,并销毁尸体:
if(player.dead)
player.die();
非常感谢你。那真的帮了我很大的忙。不客气!如果答案解决了您的问题,请不要忘记单击复选标记;)请参阅此链接