有了前面关于Android OpenGL ES的介绍,可以开始创建示例程序OpenGLDemos。
使用Eclipse 创建一个Android项目
采用Android ApiDemos 类似的方法,AndroidOpenGLDemo为一ListActivity ,可以使用PackageManager 读取所有Category为guidebee.intent.category.opengl.SAMPLE_CODE 的Activity。 Android ApiDemos示例解析(2): SimpleAdapter,ListActivity,PackageManager
创建一个OpenGLRenderer 实现 GLSurfaceView.Renderer接口:
public class OpenGLRenderer implements Renderer { private final IOpenGLDemo openGLDemo; public OpenGLRenderer(IOpenGLDemo demo){ openGLDemo=demo; } public void onSurfaceCreated(GL10 gl, EGLConfig config) { // Set the background color to black ( rgba ). gl.glClearColor(0.0f, 0.0f, 0.0f, 0.5f); // Enable Smooth Shading, default not really needed. gl.glShadeModel(GL10.GL_SMOOTH); // Depth buffer setup. gl.glClearDepthf(1.0f); // Enables depth testing. gl.glEnable(GL10.GL_DEPTH_TEST); // The type of depth testing to do. gl.glDepthFunc(GL10.GL_LEQUAL); // Really nice perspective calculations. gl.glHint(GL10.GL_PERSPECTIVE_CORRECTION_HINT, GL10.GL_NICEST); } public void onDrawFrame(GL10 gl) { if(openGLDemo!=null){ openGLDemo.DrawScene(gl); } } public void onSurfaceChanged(GL10 gl, int width, int height) { // Sets the current view port to the new size. gl.glViewport(0, 0, width, height); // Select the projection matrix gl.glMatrixMode(GL10.GL_PROJECTION); // Reset the projection matrix gl.glLoadIdentity(); // Calculate the aspect ratio of the window GLU.gluPerspective(gl, 45.0f, (float) width / (float) height, 0.1f, 100.0f); // Select the modelview matrix gl.glMatrixMode(GL10.GL_MODELVIEW); // Reset the modelview matrix gl.glLoadIdentity(); } }
为简洁起见,为所有的示例定义了一个接口IOpenGLDemo,
public interface IOpenGLDemo { public void DrawScene(GL10 gl); }
DrawScene 用于实际的GL绘图示例代码,其它的初始化工作基本就由GLSurfaceView 和OpenGLRenderer 完成,其中onSurfaceCreated 和 onSurfaceChanged 中的代码含义现在无需了解,后面会有具体介绍,只要知道它们是用来初始化GLSurfaceView就可以了。
最后使用一个简单的例子“Hello World?结束本篇,“Hello World” 使用红色背景刷新屏幕。
public class HelloWorld extends Activity implements IOpenGLDemo{ /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); this.requestWindowFeature(Window.FEATURE_NO_TITLE); getWindow() .setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN); mGLSurfaceView = new GLSurfaceView(this); mGLSurfaceView.setRenderer(new OpenGLRenderer(this)); setContentView(mGLSurfaceView); } public void DrawScene(GL10 gl) { gl.glClearColor(1.0f, 0.0f, 0.0f, 0.0f); // Clears the screen and depth buffer. gl.glClear(GL10.GL_COLOR_BUFFER_BIT | GL10.GL_DEPTH_BUFFER_BIT); } @Override protected void onResume() { // Ideally a game should implement // onResume() and onPause() // to take appropriate action when the //activity looses focus super.onResume(); mGLSurfaceView.onResume(); } @Override protected void onPause() { // Ideally a game should implement onResume() //and onPause() // to take appropriate action when the //activity looses focus super.onPause(); mGLSurfaceView.onPause(); } private GLSurfaceView mGLSurfaceView; }
其对应在AndroidManifest.xml中的定义如下:
<activity android:name=?.HelloWorld? android:label=?@string/activity_helloworld?>
<intent-filter>
<action android:name=?android.intent.action.MAIN? />
<category android:name=?guidebee.intent.category.opengl.SAMPLE_CODE? />
</intent-filter>
</activity>