libgdx 3D 渲染优化-白红宇

libgdx 3D 渲染优化

阅读量：5942 次

发布时间：2019-06-19

本文共 17246 字，大约阅读时间需要 57 分钟。

原文地址：http://blog.xoppa.com/3d-frustum-culling-with-libgdx/

非翻译，详细内容请见原文，捡点我能理解的说说吧~

关于矩阵之类的知识可以看一下 http://www.cppblog.com/lovedday/archive/2008/01/09/40813.html 我也不懂~~

渲染3D场景的时候，可见物件的数量要远远小于物件总数。

试想，在铺了一地地砖的时候，视角对着天，这时候需要渲染的地砖就没有了。摄像机照不到的地方，完全没有必要渲染。

只渲染可视视角范围内的物件，对于性能的提升是很大的。

直接上测试代码：

1 package com.mygdx.game;  2   3 import com.badlogic.gdx.ApplicationListener;  4 import com.badlogic.gdx.Gdx;  5 import com.badlogic.gdx.assets.AssetManager;  6 import com.badlogic.gdx.graphics.Camera;  7 import com.badlogic.gdx.graphics.Color;  8 import com.badlogic.gdx.graphics.GL20;  9 import com.badlogic.gdx.graphics.PerspectiveCamera; 10 import com.badlogic.gdx.graphics.g2d.BitmapFont; 11 import com.badlogic.gdx.graphics.g3d.Environment; 12 import com.badlogic.gdx.graphics.g3d.Model; 13 import com.badlogic.gdx.graphics.g3d.ModelBatch; 14 import com.badlogic.gdx.graphics.g3d.ModelInstance; 15 import com.badlogic.gdx.graphics.g3d.attributes.ColorAttribute; 16 import com.badlogic.gdx.graphics.g3d.environment.DirectionalLight; 17 import com.badlogic.gdx.graphics.g3d.utils.CameraInputController; 18 import com.badlogic.gdx.math.Vector3; 19 import com.badlogic.gdx.math.collision.BoundingBox; 20 import com.badlogic.gdx.scenes.scene2d.Stage; 21 import com.badlogic.gdx.scenes.scene2d.ui.Label; 22 import com.badlogic.gdx.utils.Array; 23  24 /** 25  * Created by HanHongmin on 14-7-24. 26  */ 27 public class FrustumCullingTestA implements ApplicationListener { 28     protected PerspectiveCamera cam; 29     protected CameraInputController camController; 30     protected ModelBatch modelBatch; 31     protected AssetManager assets; 32     protected Array
      
        instances = new Array(); 33     protected Environment environment; 34     protected boolean loading; 35  36     protected Stage stage; 37     protected Label label; 38     protected BitmapFont font; 39     protected StringBuilder stringBuilder; 40     private Vector3 tempPosition = new Vector3(); 41  42     @Override 43     public void create () { 44         stage = new Stage(); 45         font = new BitmapFont(); 46         label = new Label(" ", new Label.LabelStyle(font, Color.WHITE)); 47         stage.addActor(label); 48         stringBuilder = new StringBuilder(); 49  50         modelBatch = new ModelBatch(); 51         environment = new Environment(); 52         environment.set(new ColorAttribute(ColorAttribute.AmbientLight, 0.4f, 0.4f, 0.4f, 1f)); 53         environment.add(new DirectionalLight().set(0.8f, 0.8f, 0.8f, -1f, -0.8f, -0.2f)); 54  55         cam = new PerspectiveCamera(67, Gdx.graphics.getWidth(), Gdx.graphics.getHeight()); 56         cam.position.set(0f, 7f, 10f); 57         cam.lookAt(0,0,0); 58         cam.near = 1f; 59         cam.far = 300f; 60         cam.update(); 61  62         camController = new CameraInputController(cam); 63         Gdx.input.setInputProcessor(camController); 64  65         assets = new AssetManager(); 66         assets.load("data/box.g3db", Model.class); 67         assets.load("data/box2.g3db", Model.class); 68         loading = true; 69     } 70  71     private void doneLoading() { 72         Model t1 = assets.get("data/box.g3db", Model.class); 73         Model t2 = assets.get("data/box2.g3db", Model.class); 74  75         for(int i=0;i<100;i++){ 76             for(int j=0;j<100;j++){ 77                 Model t; 78                 if((i+j)%2==0){ 79                     t = t1; 80                 }else{ 81                     t=t2; 82                 } 83                 ModelInstance shipInstance = new ModelInstance(t); 84                 shipInstance.transform.setToTranslation(i, j, 0);//设置位置 85                 instances.add(shipInstance); 86             } 87         } 88  89         loading = false; 90     } 91  92     private int visibleCount; 93     @Override 94     public void render () { 95         if (loading && assets.update()) 96             doneLoading(); 97         camController.update(); 98  99         Gdx.gl.glViewport(0, 0, Gdx.graphics.getWidth(), Gdx.graphics.getHeight());100         Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT | GL20.GL_DEPTH_BUFFER_BIT);101 102         modelBatch.begin(cam);103         visibleCount = 0;104         for (final ModelInstance instance : instances) {105             if (isVisible(cam, instance)) {106                 modelBatch.render(instance, environment);107                 visibleCount++;108             }109         }110         modelBatch.end();111 112         stringBuilder.setLength(0);113         stringBuilder.append(" FPS: ").append(Gdx.graphics.getFramesPerSecond());114         stringBuilder.append(" Visible: ").append(visibleCount);115         label.setText(stringBuilder);116         stage.draw();117     }118 119     protected boolean isVisible(final Camera cam, final ModelInstance instance) {120         instance.transform.getTranslation(tempPosition);//把位置信息放到tempPosition中121         return cam.frustum.pointInFrustum(tempPosition);//frustum平截头体，表示的就是可视范围122     }123 124     @Override125     public void dispose () {126         modelBatch.dispose();127         instances.clear();128         assets.dispose();129     }130 131     @Override132     public void resize(int width, int height) {133         stage.getViewport().update(width, height, true);134     }135 136     @Override137     public void pause() {138     }139 140     @Override141     public void resume() {142     }143 }

View Code

以上代码中，关键部分是isVisible函数，该函数中计算了物件位置是否是在可视范围内。

这种算法稍稍有点瑕疵，运行即可看出效果。如果一个物件的位置不在可视范围内，但是此物件有一角却在，常理来说是应该显示的，而实际却没有显示出来。

上代码吧：

1 package com.mygdx.game;  2   3 import com.badlogic.gdx.ApplicationListener;  4 import com.badlogic.gdx.Gdx;  5 import com.badlogic.gdx.assets.AssetManager;  6 import com.badlogic.gdx.graphics.Camera;  7 import com.badlogic.gdx.graphics.Color;  8 import com.badlogic.gdx.graphics.GL20;  9 import com.badlogic.gdx.graphics.PerspectiveCamera; 10 import com.badlogic.gdx.graphics.g2d.BitmapFont; 11 import com.badlogic.gdx.graphics.g3d.Environment; 12 import com.badlogic.gdx.graphics.g3d.Model; 13 import com.badlogic.gdx.graphics.g3d.ModelBatch; 14 import com.badlogic.gdx.graphics.g3d.ModelInstance; 15 import com.badlogic.gdx.graphics.g3d.attributes.ColorAttribute; 16 import com.badlogic.gdx.graphics.g3d.environment.DirectionalLight; 17 import com.badlogic.gdx.graphics.g3d.utils.CameraInputController; 18 import com.badlogic.gdx.math.Vector3; 19 import com.badlogic.gdx.math.collision.BoundingBox; 20 import com.badlogic.gdx.scenes.scene2d.Stage; 21 import com.badlogic.gdx.scenes.scene2d.ui.Label; 22 import com.badlogic.gdx.utils.Array; 23  24 /** 25  * Created by HanHongmin on 14-7-24. 26  */ 27 public class FrustumCullingTest implements ApplicationListener { 28     protected PerspectiveCamera cam; 29     protected CameraInputController camController; 30     protected ModelBatch modelBatch; 31     protected AssetManager assets; 32     protected Array
     
       instances = new Array(); 33     protected Environment environment; 34     protected boolean loading; 35  36     protected Stage stage; 37     protected Label label; 38     protected BitmapFont font; 39     protected StringBuilder stringBuilder; 40     private Vector3 tempPosition = new Vector3(); 41  42     @Override 43     public void create () { 44         stage = new Stage(); 45         font = new BitmapFont(); 46         label = new Label(" ", new Label.LabelStyle(font, Color.WHITE)); 47         stage.addActor(label); 48         stringBuilder = new StringBuilder(); 49  50         modelBatch = new ModelBatch(); 51         environment = new Environment(); 52         environment.set(new ColorAttribute(ColorAttribute.AmbientLight, 0.4f, 0.4f, 0.4f, 1f)); 53         environment.add(new DirectionalLight().set(0.8f, 0.8f, 0.8f, -1f, -0.8f, -0.2f)); 54  55         cam = new PerspectiveCamera(67, Gdx.graphics.getWidth(), Gdx.graphics.getHeight()); 56         cam.position.set(0f, 7f, 10f); 57         cam.lookAt(0,0,0); 58         cam.near = 1f; 59         cam.far = 30f;//视角最远 60         cam.update(); 61  62         camController = new CameraInputController(cam); 63         Gdx.input.setInputProcessor(camController); 64  65         assets = new AssetManager(); 66         assets.load("data/box.g3db", Model.class); 67         assets.load("data/box2.g3db", Model.class); 68         loading = true; 69     } 70  71     private void doneLoading() { 72         Model t1 = assets.get("data/box.g3db", Model.class); 73         Model t2 = assets.get("data/box2.g3db", Model.class); 74  75         for(int i=0;i<100;i++){ 76             for(int j=0;j<100;j++){ 77                 Model t; 78                 if((i+j)%2==0){ 79                     t = t1; 80                 }else{ 81                     t=t2; 82                 } 83                 GameObject shipInstance = new GameObject(t); 84                 shipInstance.transform.setToTranslation(i, j, 0);//设置位置 85                 instances.add(shipInstance); 86             } 87         } 88  89         loading = false; 90     } 91  92     private int visibleCount; 93     @Override 94     public void render () { 95         if (loading && assets.update()) 96             doneLoading(); 97         camController.update(); 98  99         Gdx.gl.glViewport(0, 0, Gdx.graphics.getWidth(), Gdx.graphics.getHeight());100         Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT | GL20.GL_DEPTH_BUFFER_BIT);101 102         modelBatch.begin(cam);103         visibleCount = 0;104         for (final GameObject instance : instances) {105             if (isVisible(cam, instance)) {106                 modelBatch.render(instance, environment);107                 visibleCount++;108             }109         }110         modelBatch.end();111 112         stringBuilder.setLength(0);113         stringBuilder.append(" FPS: ").append(Gdx.graphics.getFramesPerSecond());114         stringBuilder.append(" Visible: ").append(visibleCount);115         label.setText(stringBuilder);116         stage.draw();117     }118 119     protected boolean isVisible(final Camera cam, final GameObject instance) {120         instance.transform.getTranslation(tempPosition);121         tempPosition.add(instance.center);122         return cam.frustum.boundsInFrustum(tempPosition, instance.dimensions);123     }124 125     @Override126     public void dispose () {127         modelBatch.dispose();128         instances.clear();129         assets.dispose();130     }131 132     @Override133     public void resize(int width, int height) {134         stage.getViewport().update(width, height, true);135     }136 137     @Override138     public void pause() {139     }140 141     @Override142     public void resume() {143     }144 145 146 147     public static class GameObject extends ModelInstance {148         public final Vector3 center = new Vector3();149         public final Vector3 dimensions = new Vector3();150 151         private final static BoundingBox bounds = new BoundingBox();152 153         public GameObject(Model model) {154             super(model);155             calculateBoundingBox(bounds);156             center.set(bounds.getCenter());157             dimensions.set(bounds.getDimensions());158         }159     }160 }

这个怎么算的，其实我想说：呵呵！我也不懂！！！谁整明白了请告诉我啊~

估计是看见一点就显示吧。反正是打到我们想要的效果了。

原文作者提到，当物件旋转时，可能会出现问题。贴一下原作最后的代码：

1 package com.mygdx.game;  2   3 import com.badlogic.gdx.ApplicationListener;  4 import com.badlogic.gdx.Gdx;  5 import com.badlogic.gdx.assets.AssetManager;  6 import com.badlogic.gdx.graphics.Camera;  7 import com.badlogic.gdx.graphics.Color;  8 import com.badlogic.gdx.graphics.GL20;  9 import com.badlogic.gdx.graphics.PerspectiveCamera; 10 import com.badlogic.gdx.graphics.g2d.BitmapFont; 11 import com.badlogic.gdx.graphics.g3d.Environment; 12 import com.badlogic.gdx.graphics.g3d.Model; 13 import com.badlogic.gdx.graphics.g3d.ModelBatch; 14 import com.badlogic.gdx.graphics.g3d.ModelInstance; 15 import com.badlogic.gdx.graphics.g3d.attributes.ColorAttribute; 16 import com.badlogic.gdx.graphics.g3d.environment.DirectionalLight; 17 import com.badlogic.gdx.graphics.g3d.utils.CameraInputController; 18 import com.badlogic.gdx.math.Vector3; 19 import com.badlogic.gdx.math.collision.BoundingBox; 20 import com.badlogic.gdx.scenes.scene2d.Stage; 21 import com.badlogic.gdx.scenes.scene2d.ui.Label; 22 import com.badlogic.gdx.utils.Array; 23  24 /** 25  * Created by HanHongmin on 14-7-24. 26  */ 27 public class FrustumCullingTestC implements ApplicationListener { 28     protected PerspectiveCamera cam; 29     protected CameraInputController camController; 30     protected ModelBatch modelBatch; 31     protected AssetManager assets; 32     protected Array
     
       instances = new Array(); 33     protected Environment environment; 34     protected boolean loading; 35  36     protected Stage stage; 37     protected Label label; 38     protected BitmapFont font; 39     protected StringBuilder stringBuilder; 40     private Vector3 tempPosition = new Vector3(); 41  42     @Override 43     public void create () { 44         stage = new Stage(); 45         font = new BitmapFont(); 46         label = new Label(" ", new Label.LabelStyle(font, Color.WHITE)); 47         stage.addActor(label); 48         stringBuilder = new StringBuilder(); 49  50         modelBatch = new ModelBatch(); 51         environment = new Environment(); 52         environment.set(new ColorAttribute(ColorAttribute.AmbientLight, 0.4f, 0.4f, 0.4f, 1f)); 53         environment.add(new DirectionalLight().set(0.8f, 0.8f, 0.8f, -1f, -0.8f, -0.2f)); 54  55         cam = new PerspectiveCamera(67, Gdx.graphics.getWidth(), Gdx.graphics.getHeight()); 56         cam.position.set(0f, 7f, 10f); 57         cam.lookAt(0,0,0); 58         cam.near = 1f; 59         cam.far = 30f;//视角最远 60         cam.update(); 61  62         camController = new CameraInputController(cam); 63         Gdx.input.setInputProcessor(camController); 64  65         assets = new AssetManager(); 66         assets.load("data/box.g3db", Model.class); 67         assets.load("data/box2.g3db", Model.class); 68         loading = true; 69     } 70  71     private void doneLoading() { 72         Model t1 = assets.get("data/box.g3db", Model.class); 73         Model t2 = assets.get("data/box2.g3db", Model.class); 74  75         for(int i=0;i<100;i++){ 76             for(int j=0;j<100;j++){ 77                 Model t; 78                 if((i+j)%2==0){ 79                     t = t1; 80                 }else{ 81                     t=t2; 82                 } 83                 GameObject shipInstance = new GameObject(t); 84                 shipInstance.transform.setToTranslation(i, j, 0);//设置位置 85                 instances.add(shipInstance); 86             } 87         } 88  89         loading = false; 90     } 91  92     private int visibleCount; 93     @Override 94     public void render () { 95         if (loading && assets.update()) 96             doneLoading(); 97         camController.update(); 98  99         Gdx.gl.glViewport(0, 0, Gdx.graphics.getWidth(), Gdx.graphics.getHeight());100         Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT | GL20.GL_DEPTH_BUFFER_BIT);101 102         modelBatch.begin(cam);103         visibleCount = 0;104         for (final GameObject instance : instances) {105             if (isVisible(cam, instance)) {106                 modelBatch.render(instance, environment);107                 visibleCount++;108             }109         }110         modelBatch.end();111 112         stringBuilder.setLength(0);113         stringBuilder.append(" FPS: ").append(Gdx.graphics.getFramesPerSecond());114         stringBuilder.append(" Visible: ").append(visibleCount);115         label.setText(stringBuilder);116         stage.draw();117     }118 119     protected boolean isVisible(final Camera cam, final GameObject instance) {120         instance.transform.getTranslation(tempPosition);121         tempPosition.add(instance.center);122         return cam.frustum.sphereInFrustum(tempPosition, instance.radius);123     }124 125     @Override126     public void dispose () {127         modelBatch.dispose();128         instances.clear();129         assets.dispose();130     }131 132     @Override133     public void resize(int width, int height) {134         stage.getViewport().update(width, height, true);135     }136 137     @Override138     public void pause() {139     }140 141     @Override142     public void resume() {143     }144 145 146 147     public static class GameObject extends ModelInstance {148         public final Vector3 center = new Vector3();149         public final Vector3 dimensions = new Vector3();150         public final float radius;151 152         private final static BoundingBox bounds = new BoundingBox();153 154         public GameObject(Model model) {155             super(model);156             calculateBoundingBox(bounds);157             center.set(bounds.getCenter());158             dimensions.set(bounds.getDimensions());159             radius = dimensions.len() / 2f;160         }161     }162 }

注：以上代码我都有改过，比如GameObject的构造方法。会不会有问题我真不清楚。

另外还有两点：

1. Camera的far属性能够影响可视范围，不要忘了。

2. far边缘像是被刀切了一样，一条线，far越近越明显，是否有办法根据物件和摄像机位置再次筛选是否渲染呢？

far是一条直线，摄像机正对的中点看得更远一下可能更真实。

转载于:https://www.cnblogs.com/hanhongmin/p/3866305.html

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