static EGLConfig eglConf;
static EGLSurface eglSurface;
static EGLContext eglCtx;
static EGLDisplay eglDisp;JNIEXPORT void JNICALL Java_com_handspeaker_offscreentest_MyGles_init
(JNIEnv*env,jobject obj)
{// EGL config attributesconst EGLint confAttr[] ={EGL_RENDERABLE_TYPE, EGL_OPENGL_ES2_BIT,// very important!EGL_SURFACE_TYPE,EGL_PBUFFER_BIT,//EGL_WINDOW_BIT EGL_PBUFFER_BIT we will create a pixelbuffer surfaceEGL_RED_SIZE,   8,EGL_GREEN_SIZE, 8,EGL_BLUE_SIZE,  8,EGL_ALPHA_SIZE, 8,// if you need the alpha channelEGL_DEPTH_SIZE, 8,// if you need the depth bufferEGL_STENCIL_SIZE,8,EGL_NONE};// EGL context attributesconst EGLint ctxAttr[] = {EGL_CONTEXT_CLIENT_VERSION, 2,// very important!
            EGL_NONE};// surface attributes// the surface size is set to the input frame sizeconst EGLint surfaceAttr[] = {EGL_WIDTH,512,EGL_HEIGHT,512,EGL_NONE};EGLint eglMajVers, eglMinVers;EGLint numConfigs;eglDisp = eglGetDisplay(EGL_DEFAULT_DISPLAY);if(eglDisp == EGL_NO_DISPLAY){//Unable to open connection to local windowing systemLOGI("Unable to open connection to local windowing system");}if(!eglInitialize(eglDisp, &eglMajVers, &eglMinVers)){// Unable to initialize EGL. Handle and recoverLOGI("Unable to initialize EGL");}LOGI("EGL init with version %d.%d", eglMajVers, eglMinVers);// choose the first config, i.e. best configif(!eglChooseConfig(eglDisp, confAttr, &eglConf, 1, &numConfigs)){LOGI("some config is wrong");}else{LOGI("all configs is OK");}// create a pixelbuffer surfaceeglSurface = eglCreatePbufferSurface(eglDisp, eglConf, surfaceAttr);if(eglSurface == EGL_NO_SURFACE){switch(eglGetError()){case EGL_BAD_ALLOC:// Not enough resources available. Handle and recoverLOGI("Not enough resources available");break;case EGL_BAD_CONFIG:// Verify that provided EGLConfig is validLOGI("provided EGLConfig is invalid");break;case EGL_BAD_PARAMETER:// Verify that the EGL_WIDTH and EGL_HEIGHT are// non-negative valuesLOGI("provided EGL_WIDTH and EGL_HEIGHT is invalid");break;case EGL_BAD_MATCH:// Check window and EGLConfig attributes to determine// compatibility and pbuffer-texture parametersLOGI("Check window and EGLConfig attributes");break;}}eglCtx = eglCreateContext(eglDisp, eglConf, EGL_NO_CONTEXT, ctxAttr);if(eglCtx == EGL_NO_CONTEXT){EGLint error = eglGetError();if(error == EGL_BAD_CONFIG){// Handle error and recoverLOGI("EGL_BAD_CONFIG");}}if(!eglMakeCurrent(eglDisp, eglSurface, eglSurface, eglCtx)){LOGI("MakeCurrent failed");}LOGI("initialize success!");
}

JNIEXPORT void JNICALL Java_com_handspeaker_offscreentest_MyGles_draw
(JNIEnv*env,jobject obj)
{const char*vertex_shader=vertex_shader_fix;const char*fragment_shader=fragment_shader_simple;glPixelStorei(GL_UNPACK_ALIGNMENT,1);glClearColor(0.0,0.0,0.0,0.0);glEnable(GL_DEPTH_TEST);glDepthFunc(GL_LESS);glCullFace(GL_BACK);glViewport(0,0,512,512);GLuint vertexShader = glCreateShader(GL_VERTEX_SHADER);glShaderSource(vertexShader,1,&vertex_shader,NULL);glCompileShader(vertexShader);GLuint fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);glShaderSource(fragmentShader,1,&fragment_shader,NULL);glCompileShader(fragmentShader);GLuint program = glCreateProgram();glAttachShader(program, vertexShader);glAttachShader(program, fragmentShader);glLinkProgram(program);glUseProgram(program);GLuint aPositionLocation =glGetAttribLocation(program, "a_Position");glVertexAttribPointer(aPositionLocation,2,GL_FLOAT,GL_FALSE,0,tableVerticesWithTriangles);glEnableVertexAttribArray(aPositionLocation);//draw somethingglClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);glDrawArrays(GL_TRIANGLES,0,6);eglSwapBuffers(eglDisp,eglSurface);
}

JNIEXPORT void JNICALL Java_com_handspeaker_offscreentest_MyGles_release
(JNIEnv*env,jobject obj)
{eglMakeCurrent(eglDisp, EGL_NO_SURFACE, EGL_NO_SURFACE, EGL_NO_CONTEXT);eglDestroyContext(eglDisp, eglCtx);eglDestroySurface(eglDisp, eglSurface);eglTerminate(eglDisp);eglDisp = EGL_NO_DISPLAY;eglSurface = EGL_NO_SURFACE;eglCtx = EGL_NO_CONTEXT;
}

        RGBABuffer = IntBuffer.allocate(512 * 512);MyGles.release();MyGles.init();MyGles.draw();RGBABuffer.position(0);GLES20.glReadPixels(0, 0, 512, 512,GLES20.GL_RGBA,GLES20.GL_UNSIGNED_BYTE,RGBABuffer);int[] modelData=RGBABuffer.array();int[] ArData=new int[modelData.length];int offset1, offset2;for (int i = 0; i < 512; i++) {offset1 = i * 512;offset2 = (512 - i - 1) * 512;for (int j = 0; j < 512; j++) {int texturePixel = modelData[offset1 + j];int blue = (texturePixel >> 16) & 0xff;int red = (texturePixel << 16) & 0x00ff0000;int pixel = (texturePixel & 0xff00ff00) | red | blue;ArData[offset2 + j] = pixel;}}Bitmap modelBitmap = Bitmap.createBitmap(ArData,512,512,Bitmap.Config.ARGB_8888);saveBitmap(modelBitmap);