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我正在尝试将多重采样添加到我的应用程序中，但似乎我犯了一个错误，但我找不到我做错了什么。

这就是我设置帧缓冲区和渲染缓冲区的方式

- (void)setupBuffers {
    glGenFramebuffers(1, &_framebuffer);
    glGenRenderbuffers(1, &_renderbuffer);

    glBindFramebuffer(GL_FRAMEBUFFER, _framebuffer);
    glBindRenderbuffer(GL_RENDERBUFFER, _renderbuffer);

    [_context renderbufferStorage:GL_RENDERBUFFER fromDrawable:_eaglLayer]; // I already set the current context to _context, and _eaglLayer is just self.layer

    glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_RENDERBUFFER, _renderbuffer);

    if (YES) { // note if I set this to no, my app properly displays (I don't even have to remove the code in my render method)
        glGenFramebuffers(1, &_msaa_framebuffer);
        glGenRenderbuffers(1, &_msaa_renderbuffer);

        glBindFramebuffer(GL_FRAMEBUFFER, _msaa_framebuffer);
        glBindRenderbuffer(GL_RENDERBUFFER, _msaa_renderbuffer);

        glRenderbufferStorageMultisampleAPPLE(GL_RENDERBUFFER, 2, GL_RGBA8_OES, [AppDelegate screenWidth], [AppDelegate screenHeight]); // yes, this is the proper width and height I tested it
        glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_RENDERBUFFER, _msaa_renderbuffer);
    }

    GLenum status = glCheckFramebufferStatus(GL_FRAMEBUFFER);
    if(status != GL_FRAMEBUFFER_COMPLETE) {
        NSLog(@"Failed to make complete framebuffer object %x", status);
        exit(1);
    }
}

在我调用之后viewDidLoad，我在我的子类上ViewController调用该方法。setupDisplayLinkUIView

- (void)setupDisplayLink {
    CADisplayLink* displayLink = [CADisplayLink displayLinkWithTarget:self selector:@selector(render:)];
    //displayLink.frameInterval = [[NSNumber numberWithInt:1] integerValue];
    [displayLink addToRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
}

这调用了我的渲染方法，它非常简单：

- (void)render:(CADisplayLink*)displayLink {
    glBindRenderbuffer(GL_RENDERBUFFER, _msaa_framebuffer);

    glViewport(0, 0, [AppDelegate screenWidth], [AppDelegate screenHeight]);
    glClearColor(188.0f / 255.0f, 226.0f / 255.0f, 232.0f / 255.0f, 1.0f);
    glClear(GL_COLOR_BUFFER_BIT);

    [[OpenGLViewController instance].menu draw:displayLink]; // drawing happens here

    glBindFramebuffer(GL_DRAW_FRAMEBUFFER_APPLE, _framebuffer);
    glBindFramebuffer(GL_READ_FRAMEBUFFER_APPLE, _msaa_framebuffer);

    glResolveMultisampleFramebufferAPPLE();

    glDiscardFramebufferEXT(GL_READ_FRAMEBUFFER_APPLE, 1, (GLenum[1]) { GL_COLOR_ATTACHMENT0 });

    glBindRenderbuffer(GL_RENDERBUFFER, _renderbuffer);

    NSLog(@"%@", @"HI");
    [_context presentRenderbuffer:GL_RENDERBUFFER];
}

它根本没有挂起（应用程序一直在控制台中打印“HI”，因为我在渲染方法中告诉它）。出于某种原因，当我为多重采样添加额外的帧缓冲区和渲染缓冲区时，只绘制了第一帧，我不知道为什么。它只是冻结在那个框架上。为什么我的应用只使用 MSAA 绘制第一帧？

4

1 回答 1

1

This is not surprising to say the least. The only time you have _msaa_framebuffer bound as the DRAW buffer is immediately after you initialize your FBOs.

The first time you call render (...), the following line will be drawn into your _msaa_framebuffer:

[[OpenGLViewController instance].menu draw:displayLink]; // drawing happens here

However, later on in render (...) you set the draw buffer to _framebuffer and you never change it from that point on.

To fix your problem, all you have to do is remember to bind _msaa_framebuffer as your draw buffer at the beginning of your render (...) function:

- (void)render:(CADisplayLink*)displayLink {
  glBindFramebuffer(GL_DRAW_FRAMEBUFFER_APPLE, _msaa_framebuffer);
于 2014-01-12T19:38:56.250 回答