ios – 如何使用openGL上下文设置CAEAGLLayer子类：当前绘制帧缓冲区无效

我正在尝试使用gl上下文设置CAEAGLLayer子类.也就是说,不是创建一个返回CAEAGLLayer并从UIView子类中将gl上下文绑定到该层的UIView子类,而是直接对该层进行子类化并尝试在图层的init中设置上下文,如下所示：

- (id)init
{
    self = [super init];
    if (self) {
        self.opaque = YES;

        _glContext = [[EAGLContext alloc] initWithAPI:kEAGLRenderingAPIOpenGLES2];
        NSAssert([EAGLContext setCurrentContext:_glContext],@"");

        glGenRenderbuffers(1,&_colorRenderBuffer);
        glBindRenderbuffer(GL_RENDERBUFFER,_colorRenderBuffer);
        [_glContext renderbufferStorage:GL_RENDERBUFFER fromDrawable:self];

        glGenFramebuffers(1,&_framebuffer);
        glBindFramebuffer(GL_FRAMEBUFFER,_framebuffer);
        glFramebufferRenderbuffer(GL_FRAMEBUFFER,GL_COLOR_ATTACHMENT0,GL_RENDERBUFFER,_colorRenderBuffer);

        /// . . .

到目前为止,一切似乎都很好.但是,然后我尝试创建一个带有“pass-thru”顶点/片段着色器对的着色器程序,并且在链接程序时没有返回任何错误,验证失败说：“当前绘制帧缓冲区无效.”

链接和验证着色器程序的代码(在附加着色器之后)看起来像这样,以防万一：

- (BOOL)linkAndValidateProgram
{
    GLint status;
    glLinkProgram(_shaderProgram);

#ifdef DEBUG
    GLint infoLogLength;
    GLchar *infoLog = NULL;
    glGetProgramiv(_shaderProgram,GL_INFO_LOG_LENGTH,&infoLogLength);
    if (infoLogLength > 0) {
        infoLog = (GLchar *)malloc(infoLogLength);
        glGetProgramInfoLog(_shaderProgram,infoLogLength,&infoLogLength,infoLog);
        NSLog(@"Program link log:\n%s",infoLog);
        free(infoLog);
    }
#endif

    glGetProgramiv(_shaderProgram,GL_LINK_STATUS,&status);
    if (!status) {
        return NO;
    }

    glValidateProgram(_shaderProgram);

#ifdef DEBUG
    glGetProgramiv(_shaderProgram,infoLog);
        NSLog(@"Program validation log:\n%s",GL_VALIDATE_STATUS,&status);
    if (!status) {
        return NO;
    }

    glUseProgram(_shaderProgram);
    return YES;
}

我想知道在整个CAEAGLLayer生命周期的某个时刻是否可能有一些额外的设置,我可能不知道并且可能会尝试在init中设置GL而跳过？

- (void)setBounds:(CGRect)bounds
{
    [super setBounds:bounds];
    [_context renderbufferStorage:GL_RENDERBUFFER fromDrawable:self];
    glGetRenderbufferParameteriv(GL_RENDERBUFFER,GL_RENDERBUFFER_WIDTH,&someVariableToHoldWidthIfYouNeedIt);
    glGetRenderbufferParameteriv(GL_RENDERBUFFER,GL_RENDERBUFFER_HEIGHT,&someVariableToHoldHeightIfYouNeedIt);
}