libGDX：灯光效果实现一（实现一个点光源）

news2025/10/31 10:25:49

国内的libGDX文章很少，特别是libGDX实现灯光效果，所以就开始总结灯光效果的实现

效果图.png

绿色的框是为了方便看到Body位置，使用Box2DDebugRenderer渲染的

工欲善其事，必先利其器，工具集合
gdx-setup.jar

1. 从libGDX官网下载项目生成工具

https://libgdx.com/wiki/start/setup

2.配置项目

setup配置.png
Output folder和Android SDK设置自己的，扩展库选择Box2d和Box2dlights,然后生成项目

3.配置ApplicationConfiguration，初始化ApplicationListener

由于是演示项目，所以直接使用系统创建好的Activity实现类

public class AndroidLauncher extends AndroidApplication {
   @Override
   protected void onCreate (Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      AndroidApplicationConfiguration config = new AndroidApplicationConfiguration();
      config.a = 8;
      config.r = 8;
      config.g = 8;
      config.b = 8;
      initialize(new MyGdxGame(), config);
   }
}

4.创建物理模拟环境

public class MyGdxGame extends ApplicationAdapter {
   private World mWorld;
   private Box2DDebugRenderer mWorldDebugger;
   private ArrayList bodys = new ArrayList<Body>();
   private OrthographicCamera camera;
   private ExtendViewport viewport;
   private float accumulator = 0f;
   private RayHandler rayHandler;
   private Body body;

   private static final float TIME_STEP = 1 / 120f;
   private static final int VELOCITY_ITERATIONS = 6;
   private static final int POSITION_ITERATIONS = 2;

   private int viewportWidth;
   private int viewportHeight;

   @Override
   public void create() {
      super.create();
      // 1.创建world
      mWorld = new World(new Vector2(0f, -10f), true);
      // 2.创建窗口大小，给camera用
      viewportWidth = Gdx.graphics.getWidth();
      viewportHeight = Gdx.graphics.getHeight();
      // 3.初始化正交投影相机
      initCamera();
      // 这个是为了查看body
      mWorldDebugger = new Box2DDebugRenderer();
      // 创建Body，为了让点光源依附于他(可以不设置，点光源可以单独存在)
      makeBody();
      // 创建灯光处理（核心）
      rayHandler = new RayHandler(mWorld);
      makePointLight();
   }
   
    private void makePointLight() {
       // 创建点光源 
       // rays=100 越大约逼真，但是会降低性能
       // distance=150 光照扩展的范围
       PointLight light = new PointLight(rayHandler, 100, Color.RED, 150f, 0, 0);
       light.setSoftnessLength(0); //关闭软阴影
       light.attachToBody(body, 0.5f, 0.5f);
    }

    /**
    * 初始化相机 视口大小设置为屏幕大小
    * 相机位置设置到屏幕中心
    * 这样设置是为了好理解，可以直接让模拟物体设置在哪里就显示在哪里
    * 这样就不用再去想物体和屏幕坐标的映射关系
    */
    private void initCamera() {
       camera = new OrthographicCamera(viewportWidth,
             viewportHeight);
       camera.position.x = Gdx.graphics.getWidth() / 2f;
       camera.position.y = Gdx.graphics.getHeight() / 2f;
       camera.update();
    }

    /**
    * 创建body 
    * 一个半径50的圆形，为了看清楚也可以设置大一点
    */
    private void makeBody() {
       CircleShape ballShape = new CircleShape();
       ballShape.setRadius(50f);

       FixtureDef fixtureDef = new FixtureDef();
       fixtureDef.shape = ballShape;

       BodyDef bodyDef = new BodyDef();
       bodyDef.type = BodyDef.BodyType.StaticBody;
       // 这里也是把这个圆形放到屏幕中心了（圆形是以圆心为绘制起点画圆）
       bodyDef.position.x = viewportWidth / 2f;
       bodyDef.position.y = viewportHeight / 2f;

       body = mWorld.createBody(bodyDef);
       body.createFixture(fixtureDef);
       ballShape.dispose();
    }
  }

5.render

public class MyGdxGame extends ApplicationAdapter {

    @Override
    public void render() {
       super.render();
       // 1.更新相机
       camera.update();
       // 2.清理绘制区域
       ScreenUtils.clear(Color.CLEAR);
       Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);
       // 3.时间步模拟(也可以按照官网的做固定时间步 1/60)
       doPhysicsStep(Gdx.graphics.getDeltaTime());
       // 4.给rayHandler设置matrix
       rayHandler.setCombinedMatrix(camera);
       // 5.渲染灯光
       rayHandler.updateAndRender();
       // 6.渲染body(非必须)
       mWorldDebugger.render(mWorld, camera.combined);
    }

    private void doPhysicsStep(float deltaTime) {
       // fixed time step
       // max frame time to avoid spiral of death (on slow devices)
       float frameTime = Math.min(deltaTime, 0.25f);
       accumulator += frameTime;
       while (accumulator >= TIME_STEP) {
          mWorld.step(
                TIME_STEP,
                VELOCITY_ITERATIONS,
                POSITION_ITERATIONS
          );
          accumulator -= TIME_STEP;
       }
    }
}