java - LibGDX/Java 奇怪的行为

Question

这是一款在 LibGDX 中制作的游戏。用户可以生成绵羊，然后绵羊会随机徘徊。有两个问题。

1. 羊并不总是改变他们“正确”的变量。
2. 它们似乎总是以相同的方式移动，这是不应该发生的。

这是 MainClass 和 Entity 类的代码。其他不应该是这个错误的原因。

主要:

package com.god.game;

import com.badlogic.gdx.*;
import com.badlogic.gdx.Input;
import com.badlogic.gdx.graphics.GL20;
import com.badlogic.gdx.graphics.OrthographicCamera;
import com.badlogic.gdx.graphics.g2d.SpriteBatch;
import com.badlogic.gdx.graphics.g2d.TextureAtlas;
import com.badlogic.gdx.input.GestureDetector;
import com.badlogic.gdx.math.Vector2;
import com.badlogic.gdx.math.Vector3;

import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;

public class MainClass extends ApplicationAdapter {
    public static final int width = 1600;
    public static final int height = 1000;
    public static final String title = "God Game";

    public static EntityType[] entityTypes;
    public static float rand, cameraSpeed;
    public static Comparator<Entity> layerComp;
    public static int selectedId;
    public static String aiStr;
    public static InputMultiplexer input;

    SpriteBatch batch;

    public static ArrayList<Entity> entities;
    public static OrthographicCamera camera;
    public static Vector3 mousePos;

    @Override
    public void create () {
        input = new InputMultiplexer();
        input.addProcessor(new com.god.game.Input());
        input.addProcessor(new GestureDetector(new Gestures()));
        Gdx.input.setInputProcessor(input);

        entityTypes = new EntityType[]{new EntityType("Sheep", new Vector2(55, 38), new TextureAtlas(Gdx.files.internal("Textures/sheep.atlas")), 20, new AI(new String[]{"Wander"}))};
        entities = new ArrayList<Entity>();

        layerComp = new Comparator<Entity>() {
            @Override
            public int compare(Entity e1, Entity e2) {
                if (e1.getPosition().y > e2.getPosition().y)
                    return -1;
                if (e1.getPosition().y < e2.getPosition().y)
                    return 1;
                return 0;
            }
        };

        camera = new OrthographicCamera(width, height);
        cameraSpeed = 500;
        selectedId = 0;

        batch = new SpriteBatch();
    }

    public void update(float deltaTime){

        handleInput(deltaTime);

        for(Entity e : entities){
            e.update(deltaTime);
        }

        Collections.sort(entities, layerComp);

        camera.update();
    }

    @Override
    public void render () {

        update(Gdx.graphics.getDeltaTime());

        Gdx.gl.glClearColor(0, 0.8f, 0, 1);
        Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);

        batch.setProjectionMatrix(camera.combined);
        batch.begin();
        for(Entity e : entities){
            if(!e.isRight())
                entityTypes[e.getId()].getAtlas().findRegion(e.getFrame()).flip(true, false);
            batch.draw(entityTypes[e.getId()].getAtlas().findRegion(e.getFrame()), e.getPosition().x, e.getPosition().y);
            if(!e.isRight())
                entityTypes[e.getId()].getAtlas().findRegion(e.getFrame()).flip(true, false);
        }
        batch.end();
    }

    @Override
    public void dispose(){
        batch.dispose();
        for(EntityType e : entityTypes)
            e.dispose();
    }

    public void handleInput(float deltaTime){

        mousePos = new Vector3(Gdx.input.getX(), Gdx.input.getY(), 0);
        camera.unproject(mousePos);

        if(Gdx.input.isKeyPressed(Input.Keys.W))
            camera.translate(0, cameraSpeed*deltaTime);
        if(Gdx.input.isKeyPressed(Input.Keys.A))
            camera.translate(-cameraSpeed*deltaTime, 0);
        if(Gdx.input.isKeyPressed(Input.Keys.S))
            camera.translate(0, -cameraSpeed*deltaTime);
        if(Gdx.input.isKeyPressed(Input.Keys.D))
            camera.translate(cameraSpeed*deltaTime, 0);
    }
}

实体:

package com.god.game;

import com.badlogic.gdx.math.MathUtils;
import com.badlogic.gdx.math.Vector2;

public class Entity {
    private int id;
    private Vector2 position, goalPos;
    private boolean right;
    private String frame;
    private float animationTimer;

    public Entity(int id, Vector2 position) {
        this.id = id;
        this.position = position;
        this.right = true;
        this.frame = "stand";
        this.animationTimer = 0;
        this.goalPos = Vector2.Zero;
    }

    public void update(float deltaTime){
        MainClass.aiStr = MainClass.entityTypes[id].getAi().getBrainList()[0];
        if(MainClass.aiStr == "Wander"){
            MainClass.rand = MathUtils.random(1000);

            if(MainClass.rand == 1){
                goalPos.x = -1;
                right = false;
            }
            else if(MainClass.rand == 2)
                goalPos.x = 0;
            else if(MainClass.rand == 3){
                goalPos.x = 1;
                right = true;
            }

            MainClass.rand = MathUtils.random(1000);

            if(MainClass.rand == 1)
                goalPos.y = -1;
            else if(MainClass.rand == 2)
                goalPos.y = 0;
            else if(MainClass.rand == 3)
                goalPos.y = 1;

            moveForward(deltaTime);
        }
        else{
            frame = "stand";
            animationTimer = 0;
        }
        animationTimer += deltaTime;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public Vector2 getPosition() {
        return position;
    }

    public void setPosition(Vector2 position) {
        this.position = position;
    }

    public boolean isRight() {
        return right;
    }

    public void setRight(boolean right) {
        this.right = right;
    }

    public String getFrame() {
        return frame;
    }

    public void setFrame(String frame) {
        this.frame = frame;
    }

    public float getAnimationTimer() {
        return animationTimer;
    }

    public void setAnimationTimer(float animationTimer) {
        this.animationTimer = animationTimer;
    }

    public Vector2 getGoalPos() {
        return goalPos;
    }

    public void setGoalPos(Vector2 goalPos) {
        this.goalPos = goalPos;
    }

    public void moveForward(float deltaTime){
        position.x += MainClass.entityTypes[id].getMoveSpeed() * deltaTime * goalPos.x;
        position.y += MainClass.entityTypes[id].getMoveSpeed() * deltaTime * goalPos.y;
        if(goalPos.x == 0 && goalPos.y == 0){
            frame = "stand";
            animationTimer = 0;
        }
        else if(animationTimer >= 0.2f){
            if(frame.equals("stand"))
                frame = "move";
            else
                frame = "stand";
            animationTimer = 0;
        }
    }
}

羊每次将 goalPos.x 更改为 -1 或 1 时都应该将其正确的变量设置为 true/false，但他们似乎没有这样做。它们似乎也不是独立移动的，而是像一个阵型，每次都朝着同一个方向移动。他们确实独立地将正确的变量设置为真/假，但这与他们的 Action 不匹配。例如:一只羊向右移动，然后在向右移动的同时随机向左转，等等。

任何帮助将不胜感激，谢谢!

Answer 1

首先，你永远不应该说 Java 的行为很奇怪，而应该说你的代码没有按照你的预期运行。如果您将错误归咎于某些内部 Java 功能，您将永远找不到它们。现在让我们看看如果你的人工智能设置为漫步会发生什么。

if(MainClass.aiStr == "Wander"){
        MainClass.rand = MathUtils.random(1000);
//Random number in the range of 0 to 1000.

        if(MainClass.rand == 1){ //happens .1% of the time
            goalPos.x = -1;
            right = false;
        }
        else if(MainClass.rand == 2) //happens .1% of the time
            goalPos.x = 0;
        else if(MainClass.rand == 3){ //happens .1% of the time
            goalPos.x = 1;
            right = true;
        }
 //since there is no else nothing happens 99.7% of the time.
    }

我的猜测是，您的代码的行为符合您的预期，并且您的计算机内部没有发生黑色巫术。因此，将来责怪自己并检查您的代码，实际上并没有那么多代码，您发布的内容中只有一小部分负责控制您的实体。

现在您可能想要的是这样的 MathUtils.random(1, 4) 因为最大值是独占的。或者如果您希望 25% 的时间什么都不发生，则使用 MathUtils.random(1, 5)。

就机会而言，一种更具可扩展性的方式我总是更喜欢这样的东西:

int randomNumber = MathUtils.random(1, 101);
if (randomNumber <= 33)
{
  //do something 33% of the time
}
else if (randomNumber <= 66)
{
  //do something 33% of the time
}
else
{
  //do something 34% of the time
}

现在这更容易更改，因为您所需要做的就是更改百分比，并且可以轻松添加另一个案例。

if (randomNumber <= 20)
{
  //do something 20% of the time
}
else if (randomNumber <= 60)
{
  //do something 40% of the time
}
else if (randomNumber <= 58)
{
  //do something 18% of the time
}
else
{
  //do something 22% of the time
}