OPENGL 入门

Posted 2022-08-20 changemsblog

• 检测设备支持版本,判断是否支持opengl 2.0版本
• 初始化设置OpenGLES2.0 
• 实现接口GLSurfaceView.Renderer 渲染
• 绘制图形

1、检测设备支持版本,判断是否支持opengl 2.0版本

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

2、强制应用支持

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

3、初始化设置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);
    setContentView(mGLView);


//要正常工作，OpenGL 的生命周期要跟Activity 对应上
@Override
protected void onResume() 
super.onResume();
if (mGLView!=null)
mGLView.onResume();



@Override
protected void onPause() 
super.onPause();
if (mGLView!=null)
mGLView.onPause();

4、GLSurfaceView.Renderer 渲染器，实现接口GLSurfaceView.Renderer 渲染

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、绘制图形

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);