FBO起泡不起作用

Question

我正在尝试将多采样场景渲染为纹理，这是我正在使用的代码。我得到了一个黑屏。我在init结束时检查了fbo的完整性，他们报告两个fbo都是完整的。

void init_rendered_FBO() {
    glGenFramebuffers(1,&fbo);
    glBindFramebuffer(GL_FRAMEBUFFER, fbo);
    glGenTextures(1,&fbo_tex);
    glBindTexture(GL_TEXTURE_2D, fbo_tex);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_BORDER);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_BORDER);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
    // glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, width_screen, height_screen, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL);
    glTexStorage2D(GL_TEXTURE_2D, 1, GL_RGBA8, width_screen, height_screen);
    glBindTexture (GL_TEXTURE_2D, 0);
    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, fbo_tex, 0);
    int objectType;
    glGetFramebufferAttachmentParameteriv(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_FRAMEBUFFER_ATTACHMENT_OBJECT_TYPE,&objectType);
    ASSERT(objectType == GL_TEXTURE);
    int objectName;
    glGetFramebufferAttachmentParameteriv(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_FRAMEBUFFER_ATTACHMENT_OBJECT_NAME,&objectName);
    ASSERT(glIsTexture(objectName) == GL_TRUE);
    int wid, hei, fmt;
    glBindTexture(GL_TEXTURE_2D, objectName);
    glGetTexLevelParameteriv(GL_TEXTURE_2D, 0, GL_TEXTURE_WIDTH, &wid);
    glGetTexLevelParameteriv(GL_TEXTURE_2D, 0, GL_TEXTURE_HEIGHT, &hei);
    glGetTexLevelParameteriv(GL_TEXTURE_2D, 0, GL_TEXTURE_INTERNAL_FORMAT,
            &fmt);
    glBindTexture(GL_TEXTURE_2D, 0);
    std::string format = convertInternalFormatToString(fmt);
    std::cout << "Color attachment 0: " << objectName << " " << wid << "x" << hei << ", " << format << std::endl;
    ASSERT(checkFramebufferStatus());
    glBindFramebuffer(GL_FRAMEBUFFER, 0);
}
// this is the init function that gets called.
void init_rendered_multisample_FBO() {
    init_rendered_FBO();
    // now I'm going to set up the additional component necessary to perform multisampling which is a new fbo
    // that has a multisampled color buffer attached. I won't need a multisample depth buffer.
    glGenFramebuffers(1,&multi_fbo);
    glBindFramebuffer(GL_FRAMEBUFFER,multi_fbo);
    glGenRenderbuffers(1,&renderbuffer_multi);
    glBindRenderbuffer(GL_RENDERBUFFER,renderbuffer_multi);
    glRenderbufferStorageMultisample(GL_RENDERBUFFER, 4, GL_RGBA, width_screen,height_screen);
    glBindRenderbuffer(GL_RENDERBUFFER,0);
    glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_RENDERBUFFER, renderbuffer_multi);
    int objectType;
    glGetFramebufferAttachmentParameteriv(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_FRAMEBUFFER_ATTACHMENT_OBJECT_TYPE,&objectType);
    ASSERT(objectType == GL_RENDERBUFFER);
    int objectName;
    glGetFramebufferAttachmentParameteriv(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_FRAMEBUFFER_ATTACHMENT_OBJECT_NAME,&objectName);
    ASSERT(glIsRenderbuffer(objectName) == GL_TRUE);
    glBindRenderbuffer(GL_RENDERBUFFER,objectName);
    int wid,hei,fmt,sam;
    glGetRenderbufferParameteriv(GL_RENDERBUFFER,GL_RENDERBUFFER_WIDTH,&wid);
    glGetRenderbufferParameteriv(GL_RENDERBUFFER,GL_RENDERBUFFER_HEIGHT,&hei);
    glGetRenderbufferParameteriv(GL_RENDERBUFFER,GL_RENDERBUFFER_INTERNAL_FORMAT,&fmt);
    glGetRenderbufferParameteriv(GL_RENDERBUFFER,GL_RENDERBUFFER_SAMPLES,&sam);
    glBindRenderbuffer(GL_RENDERBUFFER,0);
    printf("Renderbuffer: %dx%d, fmt=%d, samples=%dn",wid,hei,fmt,sam);
    ASSERT(checkFramebufferStatus());
    glBindFramebuffer(GL_FRAMEBUFFER, 0);
}
// this is called after rendering to multi_fbo
void resolve_multisample_FBO() {
    glBindFramebuffer(GL_READ_FRAMEBUFFER, multi_fbo);
    glReadBuffer(GL_COLOR_ATTACHMENT0);
    glBindFramebuffer(GL_DRAW_FRAMEBUFFER, fbo);
    GLenum drawbuf = GL_COLOR_ATTACHMENT0;
    glDrawBuffers(1,&drawbuf);
    glBlitFramebuffer(0,0,width_screen,height_screen,0,0,width_screen,height_screen,GL_COLOR_BUFFER_BIT,GL_NEAREST);
}

你能发现我遗漏的东西吗？我认为问题可能与glFramebufferRenderbuffer通话有关。我尝试将第一个arg切换到GL_READ_FRAMEBUFFER，但没有修复。

我检查了glGetError，没有错误。如果我设置了错误的东西，肯定会失败，并给我INVALID_ENUM或INVALID_OPERATION来帮助我缩小问题范围。

我使用此代码的方式是，为了启用多重采样，我所要更改的就是在绘图时绑定multi_fbo，然后调用解析函数，该函数将进行绑定和blit。之后，我的fbo纹理（直接渲染时效果良好）现在应该包含多采样渲染。但它只是黑色的。在初始化代码的另一部分中，我也调用了glEnable(GL_MULTISAMPLE)。

我现在要尝试将一个非多采样纹理闪电战到另一个纹理，以确保它有效。希望这能帮助我缩小我搞砸的地方。

更新：因此，将一个常规FBO复制到另一个相同的FBO（两者都有附加到颜色附件0的纹理）会产生相同的黑屏。闪电战根本不起作用。

同样奇怪的是，一旦我尝试闪电战，然后绘制SOURCE fbo的纹理，它仍然是全黑的。这就像试图闪电战只会毁掉一切。

有人知道或有任何FBO闪电战代码吗？我找不到任何，但我知道人们已经得到了多样本FBO的工作。

以下是您可以提供帮助的方法：如果您有在任何时候调用glBlitFramebuffer的代码，我希望看到其他用于设置该操作的调用。一旦我调用它，除了黑色缓冲区和纹理，我似乎什么都得不到。

更新：Blit-to-backbuffer有效，即使使用多重采样！这当然不需要任何设置，因为我只绑定了帧缓冲区0。所以问题似乎是我设置的FBO，它有一个纹理附件，应该被闪电传送到。

Answer 1

事实证明，除了重置帧缓冲区绑定失败之外，我没有做错任何事情。

在void resolve_multisample_FBO()结束时，我只需要一个glBindFramebuffer(GL_FRAMEBUFFER, 0);

我向你保证，浪费3个小时真是太可怕了。但多重采样看起来很棒，而且弥补了这一点。