OPENGL entry

Testing equipment supported versions, to determine whether to support opengl version 2.0
Initial Setup OpenGLES2.0
Implement the interface rendering GLSurfaceView.Renderer
Graphing

1, the detection device support version, version 2.0 is determined whether to support opengl

private boolean hasGLES20(){
    ActivityManager activityManager=(ActivityManager)getSystemService(Context.ACTIVITY_SERVICE);
    ConfigurationInfo info=activityManager.getDeviceConfigurationInfo();
    return info.reqGLEsVersion>=0x20000;
}

2, mandatory application support

<uses-feature android:glEsVersion="0x00020000"
              android:required="true"/>

3, initial setup OpenGLES2.0

@Override
protected void onCreate(Bundle savedInstanceState){
   //设置全屏模式
    requestWindowFeature(Window.FEATURE_NO_TITLE);
    getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,WindowManager.LayoutParams.FLAG_FULLSCREEN);
    if（hasGLES20()）{
        GLSurfaceView mGLView=new GLSurfaceView(this);
        mGLView.setEGLContextClientVersion(2);
//保留OpenGLESs上下文
        mGLView.setPreserveEGLContextOnPause(true);
        mGLView.setRenderer(new GLES20Renderer());
    }
    Super .onCreate (savedInstanceState); 
    the setContentView (mGLView); 
} 

// to work properly, to keep the life cycle corresponding to the OpenGL Activity 
@Override
 protected  void onResume () {
 Super .onResume ();
 IF (! mGLView = null ) { 
mGLView.onResume (); 
} 
} 

@Override 
protected  void the onPause () {
 Super .onPause ();
 IF (mGLView =! null ) { 
mGLView.onPause (); 
} 
}

4, GLSurfaceView.Renderer renderer, rendering implement the interface GLSurfaceView.Renderer

public abstract class GLRenderer implements GLSurfaceView.Renderer{
    

private boolean mFirstDraw;
private boolean mSurfaceCreated;
private int mWidth;
private int mHeight;
private long mLastTime;
private int mFPS;
    

@Override
public void onSurfaceCreated(GL10 gl, EGLConfig config) {
    mSurfaceCreated=true;
    mWidth=-1;
    mHeight=-1;
}

@Override
public void onSurfaceChanged(GL10 gl, int width, int height) {
    if (!mSurfaceCreated&&width==mWidth&&height==mHeight){
        return;
    }
    mWidth=width;
    mHeight=height;
    onCreate(mWidth,mHeight,mSurfaceCreated);
    mSurfaceCreated=false;
}

@Override
public void onDrawFrame(GL10 gl) {
    onDrawFrame(mFirstDraw);
    if (mFirstDraw){
        mFirstDraw=false;
    }
}
public abstract void onCreate(int width,int height,boolean contextLost);
public abstract void onDrawFrame(boolean firstDraw);
public int getFPS(){
    return mFPS;
}

}

5, draw graphics

public class GLES20Renderer extends GLRenderer {
 
    @Override
    public void onCreate(int width, int height,
            boolean contextLost) {
        GLES20.glClearColor(0f, 0f, 0f, 1f);
    }
 
    @Override
    public void onDrawFrame(boolean firstDraw) {
        GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT
                | GLES20.GL_DEPTH_BUFFER_BIT);
    }
}

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