我正在尝试使用Bullet包装器在Libgdx中创建一个SELECT `Chat`.`id`,
`Chat`.`sender_id`,
`Chat`.`receiver_id`,
`Chat`.`message`,
`Chat`.`datetime`,
`Chat`.`converstation_id`
FROM `gopher`.`chat` AS `Chat`
WHERE ((`Chat`.`sender_id` = 10) OR (`Chat`.`receiver_id` = 10))
GROUP BY converstation_id
ORDER BY `Chat`.`id` DESC LIMIT 0,1
派生类，用于碰撞检测，就像在这个tutorial中一样，但是在不同的类中。它将渲染和游戏世界的类分开。在类ContactListener的{{1}}方法中，我将一个模型实例Array传递给此派生类。但是当我运行它时会给出一个因为数组大小为零。这是派生类：
render()这是Renderer类：
Render我做错了什么？在package com.anutrix.brickbreaker3d.Helpers;
import com.badlogic.gdx.Gdx;
import com.badlogic.gdx.graphics.g3d.ModelInstance;
import com.badlogic.gdx.physics.bullet.collision.ContactListener;
import com.badlogic.gdx.utils.Array;
public class CollisionListener extends ContactListener {
private Array<ModelInstance> instances;
public CollisionListener() {
this.instances = new Array<ModelInstance>();
}
public void setModelInstances(Array<ModelInstance> instances) {
this.instances = instances;
}
@Override
public boolean onContactAdded(int userValue0, int partId0, int index0, int userValue1, int partId1, int index1) {
//instances.get(colObj1Wrap.getCollisionObject().getUserValue()).collided = false;error
Gdx.app.log("instances.size", Integer.toString(instances.size));//zero
Gdx.app.log("ddhbdfhd", "fhfgjfgj");
return true;
}
}
内，instances.size是正确的。但在每次调用之后，package com.anutrix.brickbreaker3d.gameWorld;
import com.anutrix.brickbreaker3d.gameObjects.Ball;
import com.anutrix.brickbreaker3d.gameObjects.Brick;
import com.badlogic.gdx.Gdx;
import com.badlogic.gdx.graphics.GL20;
import com.badlogic.gdx.graphics.PerspectiveCamera;
import com.badlogic.gdx.graphics.g3d.Environment;
import com.badlogic.gdx.graphics.g3d.ModelBatch;
import com.badlogic.gdx.graphics.g3d.ModelInstance;
import com.badlogic.gdx.graphics.g3d.attributes.ColorAttribute;
import com.badlogic.gdx.graphics.g3d.environment.DirectionalLight;
import com.badlogic.gdx.graphics.g3d.utils.CameraInputController;
import com.badlogic.gdx.graphics.g3d.utils.ModelBuilder;
import com.badlogic.gdx.physics.bullet.DebugDrawer;
import com.badlogic.gdx.physics.bullet.collision.btCollisionDispatcher;
import com.badlogic.gdx.physics.bullet.collision.btCollisionWorld;
import com.badlogic.gdx.physics.bullet.collision.btDbvtBroadphase;
import com.badlogic.gdx.physics.bullet.collision.btDefaultCollisionConfiguration;
import com.badlogic.gdx.physics.bullet.linearmath.btIDebugDraw;
import com.badlogic.gdx.utils.Array;
import com.badlogic.gdx.utils.Disposable;
public class GameRenderer implements Disposable {
private GameWorld gameWorld;
private PerspectiveCamera cam;
public ModelBatch modelBatch;
private CameraInputController camController;
private Environment environment;
public Array<ModelInstance> instances;
ModelBuilder mb = new ModelBuilder();
btCollisionDispatcher dispatcher;
public GameRenderer(GameWorld world) {
this.modelBatch = new ModelBatch();
this.environment = new Environment();
this.instances = new Array<ModelInstance>();
gameWorld = world;
cam = new PerspectiveCamera(67, Gdx.graphics.getWidth(), Gdx.graphics.getHeight());
cam.position.set(10f, 10f, 0f);
cam.lookAt(0, 0, 0);
cam.near = 1f;
cam.far = 300f;
cam.update();
camController = new CameraInputController(cam);
Gdx.input.setInputProcessor(camController);
environment.set(new ColorAttribute(ColorAttribute.AmbientLight, 0.4f, 0.4f, 0.4f, 1f));
environment.add(new DirectionalLight().set(0.8f, 0.8f, 0.8f, -1f, -0.8f, -0.2f));
}
public void render() {
//Gdx.app.log("GameRenderer", "render");
Gdx.gl.glViewport(0, 0, Gdx.graphics.getWidth(), Gdx.graphics.getHeight());
Gdx.gl.glClearColor(0f, 0.2f, 0.2f, 1);
Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT | GL20.GL_DEPTH_BUFFER_BIT);
for (Brick b : gameWorld.bricks) {
b.getObject().setUserValue(instances.size);
instances.add(b.getModelInstance());
}
for (Ball b : gameWorld.balls) {
b.getObject().setUserValue(instances.size);
instances.add(b.getModelInstance());
}
gameWorld.collisionListener.setModelInstances(instances);
modelBatch.begin(cam);
modelBatch.render(instances, environment);
modelBatch.end();
instances.clear();
}
@Override
public void dispose() {
modelBatch.dispose();
}
}
等于0。
此外，我不确定通过引用传递（因为Java使用pass by value）。如果我只调用setModelInstances()一次，那么它是否更好（如果有效）？
答案 0 :(得分：2)
在CollisionListener#instances方法中调用GameRenderer#instances后，gameWorld.collisionListener.setModelInstances(instances);和GameRenderer#render()都指向相同的引用。
然后，在方法结束时，您正在调用：
instances.clear();
这将清除instances。因此，当您拨打render时，大小将变为0。
相反，在setModelInstances方法中，您可以创建一个新的Array实例，如下所示：
public void setModelInstances(Array<ModelInstance> instances) {
this.instances = new Array<>(instances);
}
希望这有帮助！