-[EAGLContext renderbufferStorage:fromDrawable:] 第二次失败？

我正在开发一个 iOS openGL ES 应用程序。

我正在做通常的 EAGLView / ES2Render 的事情。

启动时，使用以下代码成功创建 frambuffer：

- (BOOL) createFramebuffers
{
    [EAGLContext setCurrentContext:_mainContext];

    // [ A ] On-screen  

    // 1. Framebuffer
    glGenFramebuffers(1, &_mainFramebuffer);
    bindFramebuffer(_mainFramebuffer);

    // 2. Color buffer
    glGenRenderbuffers(1, &_mainColorbuffer);
    bindRenderbuffer(_mainColorbuffer);

    // Adjust size to view's layer:
    CAEAGLLayer* layer = (CAEAGLLayer*)[_view layer];

    if (![_mainContext renderbufferStorage:GL_RENDERBUFFER fromDrawable:layer]) {
        // something went horribly wrong
        NSLog(@"-[ES2Renderer createFramebuffers]: Failed to obtain renderbuffer storage from layer!");
        return NO;
    }

    // Query new size:
    glGetRenderbufferParameteriv(GL_RENDERBUFFER, GL_RENDERBUFFER_WIDTH,  &_backingWidth);
    glGetRenderbufferParameteriv(GL_RENDERBUFFER, GL_RENDERBUFFER_HEIGHT, &_backingHeight);

    // Attach to color:
    glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_RENDERBUFFER, _mainColorbuffer);

    // 3. Depth buffer
    glGenRenderbuffers(1, &_depthBuffer);
    bindRenderbuffer(_depthBuffer);

    if (_useStencilBuffer) {
        // Depth + Stencil

        // Allocate storage:
        glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH24_STENCIL8_OES, _backingWidth, _backingHeight);

        // Attach to depth:
        glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, _depthBuffer);

        // Attach to stencil:
        glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_STENCIL_ATTACHMENT, GL_RENDERBUFFER, _depthBuffer);
    }
    else{
        // Depth only

        // Allocate storage:
        glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT24_OES, _backingWidth, _backingHeight);

        // Attachto depth:
        glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, _depthBuffer);

    }

    // 4. Validate the set:
    GLenum framebufferStatus = glCheckFramebufferStatus(GL_FRAMEBUFFER);

    if (framebufferStatus != GL_FRAMEBUFFER_COMPLETE) {
        // Something went wrong!

        NSLog(@"-[ES2Renderer createFramebuffers]: Failed to make complete framebuffer object: %@",
              [self stringFromFramebufferStauts:framebufferStatus]);

        return NO;
    }

    // [ B ] Off-screen (Render-to-texture)

    // 1. Framebuffer
    glGenFramebuffers(1, &_transFramebuffer);
    bindFramebuffer(_transFramebuffer);

    // 2. Depth buffer
    glGenRenderbuffers(1, &_transDepthBuffer);
    bindRenderbuffer(_transDepthBuffer);

    if (_useStencilBuffer) {
        // Allocate storage:
        glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH24_STENCIL8_OES, _backingWidth, _backingHeight);

        // Attach to depth:
        glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, _transDepthBuffer);

        // Attach to stencil:
        glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_STENCIL_ATTACHMENT, GL_RENDERBUFFER, _transDepthBuffer);
    }
    else{
        // Allocate storage
        glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT24_OES, _backingWidth, _backingHeight);

        // Attach to depth:
        glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, _transDepthBuffer);
   }


    // 3. Textures (color buffers)

    GLuint* texPtrs[2] = {&_transTexture1, &_transTexture2};

    for (NSUInteger i=0; i < 2; i++) {

        GLuint* texPtr = texPtrs[i];

        // Create:
        glGenTextures(1, texPtr);

        // Bind:
        bindTexture2D(*texPtr);

        // Configure for pixel-aligned use:
        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);

        // Allocate storage:
        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, _backingWidth, _backingHeight, 0, GL_RGBA, GL_UNSIGNED_BYTE, 0);

        // Attach:
        glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, *texPtr, 0);

        framebufferStatus = glCheckFramebufferStatus(GL_FRAMEBUFFER);

        // Validate:
        if ( framebufferStatus != GL_FRAMEBUFFER_COMPLETE) {
            // Something went wrong!

            NSLog(@"-[ES2Renderer createFramebuffers]: Failed to make complete framebuffer object: %@",
                  [self stringFromFramebufferStauts:framebufferStatus]);

            return NO;
        }
    }

    // Final State:

    bindFramebuffer(_mainFramebuffer);
    bindRenderbuffer(_mainColorbuffer);
    bindTexture2D(0);


    NSLog(@"-[ES2Renderer createFramebuffers] Succeeded.");
    return YES;
}

不久之后，UIView's -layoutSubviews被调用，我依次执行-resizeFromLayer::

- (BOOL) resizeFromLayer:(CAEAGLLayer *)layer
{
    // [ A ] On screen framebuffer

    bindFramebuffer(_mainFramebuffer);

    // 1. Resize color buffer
    bindRenderbuffer(_mainColorbuffer);

    if (![_mainContext renderbufferStorage:GL_RENDERBUFFER fromDrawable:layer]) {
        // Something went wrong
        return NO; // <-- SECOND TIME ON, THIS HAPPENS
    }

    // Query new size:
    glGetRenderbufferParameteriv(GL_RENDERBUFFER, GL_RENDERBUFFER_WIDTH,  &_backingWidth);
    glGetRenderbufferParameteriv(GL_RENDERBUFFER, GL_RENDERBUFFER_HEIGHT, &_backingHeight);

    // 2. Resize depth buffer
    bindRenderbuffer(_depthBuffer);

    if (_useStencilBuffer) {
        // (Depth & Stencil)

        glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH24_STENCIL8_OES, _backingWidth, _backingHeight);
    }
    else{
        // (Depth only)

        glRenderbufferStorage(GL_FRAMEBUFFER, GL_DEPTH_COMPONENT24_OES, _backingWidth, _backingHeight);
    }

    // ...Validate:
    GLenum framebufferStatus = glCheckFramebufferStatus(GL_FRAMEBUFFER);

    if (framebufferStatus != GL_FRAMEBUFFER_COMPLETE) {
        // Something went wrong!

        NSLog(@"-[ES2Renderer resizeFromLayer:]: Failed to make complete framebuffer object: %@",
              [self stringFromFramebufferStauts:glCheckFramebufferStatus(GL_FRAMEBUFFER)]);

        return NO;
    }

    // [ B ] Off screen (render-to-terxture) framebuffer

    bindFramebuffer(_transFramebuffer);

    // 1. Resize depth buffer

    bindRenderbuffer(_transDepthBuffer);

    if (_useStencilBuffer) {
        glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH24_STENCIL8_OES, _backingWidth, _backingHeight);
    }
    else{
        glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT24_OES, _backingWidth, _backingHeight);        
    }


    // 2. Resize textures

    GLuint* texPtrs[2] = {&_transTexture1, &_transTexture2};

    for (NSUInteger i=0; i < 2; i++) {

        GLuint* texPtr = texPtrs[i];

        // Bind:
        bindTexture2D(*texPtr);

        // Configure for pixel-aligned use:
        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);

        // Allocate storage:
        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, _backingWidth, _backingHeight, 0, GL_RGBA, GL_UNSIGNED_BYTE, 0);

        // Attach:
        glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, *texPtr, 0);


        // Validate:
        if (glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE) {
            // Something went wrong!
            NSString* statusString = [self stringFromFramebufferStauts:glCheckFramebufferStatus(GL_FRAMEBUFFER)];
            NSLog(@"-[ES2Renderer resizeFromLayer:]: Failed to make complete framebuffer object: %@", statusString);
            return NO;
        }
    }

    bindFramebuffer(_mainFramebuffer);
    bindRenderbuffer(_mainColorbuffer);


    // Pass new ortho projection to shaders
    [self initializeModelViewMatrix];
    [self initializeSpriteProgram];

    // Set new viewport
    glViewport(0, 0, _backingWidth, _backingHeight);

    NSLog(@"-[ES2Renderer resizeFromLayer:]: Succeeded.");

    return YES;
}

我正在做的事情没有什么特别的。我有一个单独的帧缓冲区来渲染场景过渡，并有两个纹理附加到颜色和深度。

第二次-renderbufferStorage:fromDrawable:叫做 （-layoutSubviews -> resizeFromLayer:），它总是失败（返回NO）；呼唤glGetError()在此之前不会产生错误，但在返回后立即调用它GL_INVALID_OPERATION。 如果我忽略这一点并继续，glGetRenderbufferParameteriv()仍然可以得到正确的宽度和高度（在 iPhone 5 上分别为 640 和 1136），但是glCheckFramebufferStatus()将返回GL_FRAMEBUFFER_UNSUPPORTED.

或者，我跳过了上面的内容resizeFromLayer:并将其替换为：

- (BOOL) resizeFromLayer:(CAEAGLLayer *)layer
{
    [self destroyFramebuffers];

    return [self createFramebuffers];
}

...但同样的错误仍然存​​在（-renderStorage:fromDrawable:失败；这次在里面-createFramebuffers).

现在我只是回来YES（我的应用程序仅支持纵向，因此实际上不会发生屏幕尺寸变化），但我真的想修复它，因为有一天我需要支持横向等......

One possible理由是renderbufferStorage:fromDrawable:失败的是_mainContext不是当时的当前上下文。尽管看起来没有其他上下文可以窃取“当前”状态，但我建议致电[EAGLContext setCurrentContext:_mainContext]在任何之前gl or EAGL对与该上下文关联的对象进行操作的代码（例如，在resizeFromLayer:方法）。