egl gles2.0开发

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在android中，java层需要创建surface，

class MobileViewGLES extends GLSurfaceView implements Callback{   public void surfaceCreated(SurfaceHolder holder)    {        Log.e("MobileViewGLES", "surfaceCreated");         //new Thread(this).start();        initRenderGLES( getHolder().getSurface() );    }     public void surfaceChanged(SurfaceHolder holder, int format, int width, int height)    {           Log.e("MobileViewGLES", "surfaceChanged");     }    public void surfaceDestroyed(SurfaceHolder holder)     {         Log.e("MobileViewGLES", "surfaceDestroyed");         termRenderGLES();    }     public native void initRenderGLES( Surface surface );        public native void termRenderGLES();}

initRenderGLES是Native函数，在c++层实现，该函数主要创建gles环境，绘制的surface和display，实现函数如下：

static void MobileViewGLES_InitRenderGLES( JNIEnv *env, jobject thiz, jobject surface ){    gANativeWindow = ANativeWindow_fromSurface( env, surface );    GlesInitDisplay();    CreateGlesEnv();    GlesEnvChanged( gWidth, gHeight );    SetDrawOffScreen( false );    //GlesDrawFrame();    //GlesTermDisplay();    return;}GlesInitDisplay()如下：int GlesInitDisplay(){    const EGLint attribs[] =    {        EGL_SURFACE_TYPE,        EGL_WINDOW_BIT,        EGL_BLUE_SIZE, 8,        EGL_GREEN_SIZE, 8,        EGL_RED_SIZE, 8,        EGL_NONE    };    EGLConfig config;    EGLint numConfigs;    EGLint format;    EGLint width;    EGLint height;    EGLint contextAtt[] = { EGL_CONTEXT_CLIENT_VERSION, 2, EGL_NONE, EGL_NONE };    gDisplay = eglGetDisplay( EGL_DEFAULT_DISPLAY );    eglInitialize( gDisplay, 0, 0 );    eglChooseConfig( gDisplay, attribs, &config, 1, &numConfigs );    eglGetConfigAttrib( gDisplay, config, EGL_NATIVE_VISUAL_ID, &format );    ANativeWindow_setBuffersGeometry( gANativeWindow, 0, 0, format);    gSurface = eglCreateWindowSurface( gDisplay, config, gANativeWindow, NULL);    gContext = eglCreateContext( gDisplay, config, EGL_NO_CONTEXT, contextAtt);    if (eglMakeCurrent( gDisplay, gSurface, gSurface, gContext) == EGL_FALSE)    {        LOGE("Unable to eglMakeCurrent");        return -1;    }    eglQuerySurface( gDisplay, gSurface, EGL_WIDTH, &width );    eglQuerySurface( gDisplay, gSurface, EGL_HEIGHT, &height );    return 0;}GLint CreateGlesEnv( ){    static char vShaderStr[] =        "uniform mat4 u_TransMatrix;                    \n"        "attribute vec4 a_position;                       \n"        "attribute vec2 a_texCoord;                       \n"        "varying vec2 v_texCoord;                         \n"        "void main()                                      \n"        "{                                                \n"        "   gl_Position = u_TransMatrix * a_position;     \n"        "   v_texCoord = a_texCoord;                      \n"        "}                                                \n";    static char fShaderStr[] =      "precision mediump float;                                    \n"      "varying vec2 v_texCoord;                                     \n"      "uniform sampler2D s_ImgTexture;                             \n"      "uniform int specColorFlag;                                    \n"      "uniform vec4 specColor;                                        \n"      "void main()                                                 \n"      "{                                                           \n"      //"       gl_FragColor = texture2D( s_ImgTexture, v_texCoord );\n"      " if (specColorFlag == 0)                                 \n"      " {gl_FragColor = texture2D( s_ImgTexture, v_texCoord );} \n"      " else {gl_FragColor = specColor;}                         \n"      "}                                                           \n";    //esOrtho(&gOrthographic, -100, 100, -100, 100, 5.0f, -5.0f );    GLuint vertexShader;    GLuint fragmentShader;    GLuint programObject;    GLint linked;    // Load the vertex/fragment shaders    vertexShader = esLoadShader ( GL_VERTEX_SHADER, vShaderStr );    if ( vertexShader == 0 )      return 0;    fragmentShader = esLoadShader ( GL_FRAGMENT_SHADER, fShaderStr );    if ( fragmentShader == 0 )    {      glDeleteShader( vertexShader );      return 0;    }    gProObject = glCreateProgram ( );    glAttachShader ( gProObject, vertexShader );    glAttachShader ( gProObject, fragmentShader );    // Link the program    glLinkProgram ( gProObject );    // Check the link status    glGetProgramiv ( gProObject, GL_LINK_STATUS, &linked );    if ( !linked )    {      GLint infoLen = 0;      glGetProgramiv ( gProObject, GL_INFO_LOG_LENGTH, &infoLen );      if ( infoLen > 1 )      {         char* infoLog = (char *)malloc (sizeof(char) * infoLen );         glGetProgramInfoLog ( gProObject, infoLen, NULL, infoLog );         free ( infoLog );      }      glDeleteProgram ( gProObject );      return 0;    }    // Free up no longer needed shader resources    glDeleteShader ( vertexShader );    glDeleteShader ( fragmentShader );    gShaderPosition = glGetAttribLocation ( gProObject, "a_position" );    gShaderTexCoord = glGetAttribLocation ( gProObject, "a_texCoord" );    gvpMatrix          = glGetUniformLocation( gProObject, "u_TransMatrix" );    gShaderImgTexture = glGetUniformLocation ( gProObject, "s_ImgTexture" );    gColorFlag        = glGetUniformLocation( gProObject, "specColorFlag" );    gColorLoc        = glGetUniformLocation( gProObject, "specColor" );    //glEnable (GL_BLEND);    //glBlendFunc (GL_SRC_ALPHA, GL_ONE_MINUS_SRC_COLOR);    glGenTextures(1, &gMainTexture );    glGenTextures(1, &gTextureTmp);    GlesBindOffScreen();    glPixelStorei(GL_UNPACK_ALIGNMENT, 1);    glBindTexture(GL_TEXTURE_2D, gTextureTmp);    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE );    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE );    glTexImage2D(GL_TEXTURE_2D,            0,            GL_RGBA,            gWidth,            gHeight,            0,            GL_RGBA,            GL_UNSIGNED_BYTE,            NULL );    return gProObject;}void GlesEnvChanged(  int width, int height ){    gWidthd2 = width / 2;    gHeightd2 = height / 2;    esMatrixLoadIdentity( &gOrthographic );    //esOrtho(&gOrthographic, 0, mWidth, -mHeight, 0, 5.0f, -5.0f );    esOrtho(&gOrthographic, -gWidthd2, gWidthd2, -gHeightd2, gHeightd2, 5.0f, -5.0f );    ESMatrix modelview;    esMatrixLoadIdentity( &gMatrix );    esMatrixLoadIdentity( &modelview );    esMatrixMultiply( &gMatrix, &modelview, &gOrthographic );    glViewport(0, 0, width, height);}void SetDrawOffScreen(bool bOffScreen ){    if ( bOffScreen )    {        glBindFramebuffer(GL_FRAMEBUFFER, gFrameBuffer);    }    else    {        glBindFramebuffer(GL_FRAMEBUFFER, 0);    }}通过上面步骤，gles环境创建完成，下面就是绘制        case XWM_REPAINT:        {            if( eglMakeCurrent( gDisplay, gSurface, gSurface, gContext) == EGL_FALSE )            {                LOGWHEREMSG("MakeCurrent Error");                break;            }            LOGWHEREMSG( "XWM_REPAINT" );            XRect clip(m_clip);            glClearColor( 0.0f, 0.0f,  0.0f, 1.0f );            glBindFramebuffer(GL_FRAMEBUFFER, gFrameBuffer);            bool b = Paint(m_draw);            if( b )            {                glClearColor( 0.0f, 0.0f,  0.0f, 1.0f );                glBindFramebuffer(GL_FRAMEBUFFER, 0);                GlesPaint( gMainTexture );                FlushBuffer();                LOGWHEREMSG( "XWM_REPAINT" );            }            else            {                InvalidateRect(clip);            }            break;        }

绘制过程中，glBindFramebuffer(GL_FRAMEBUFFER, gFrameBuffer)设置绘制在离屏缓存区上，而glBindFramebuffer(GL_FRAMEBUFFER, 0)则绘制在屏幕上

最后，在结束时通过调用termRenderGLES()函数，销毁surface，函数实现如下：

int GlesTermDisplay(){    if( gDisplay != EGL_NO_DISPLAY )    {        eglMakeCurrent( gDisplay, EGL_NO_SURFACE, EGL_NO_SURFACE, EGL_NO_CONTEXT );        if( gContext != EGL_NO_CONTEXT )        {            eglDestroyContext( gDisplay, gContext );        }        if( gSurface != EGL_NO_SURFACE )        {            eglDestroySurface( gDisplay, gDisplay );        }        eglTerminate( gDisplay );    }}

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