FBO Blitting无效

Question

我正在尝试将多重采样的场景渲染为纹理,这是我正在使用的代码.我有黑屏.我在init结束时检查fbo完整性,并且他们报告两个fbo都已完成.

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=%d\n",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);
}

你能发现我遗漏的任何东西吗？我认为这个问题可能与glFramebufferRenderbuffer电话有关.我尝试将第一个arg切换到GL_READ_FRAMEBUFFER但它没有修复.

我检查glGetError并没有错误.如果我设置错误,肯定有些事情会失败并给我INVALID_ENUM或INVALID_OPERATION帮助我缩小问题的范围.

我使用此代码的方式是,为了启用多重采样,我必须更改的是在绘制时绑定multi_fbo,然后调用将绑定和blit的resolve函数.之后,我的fbo纹理(当我直接渲染它时工作正常)现在应该包含多重采样渲染.但它只是黑色.我还调用glEnable(GL_MULTISAMPLE)了另一部分初始化代码.

我现在要尝试将非多重采样纹理blit到另一个纹理以确保其有效.希望这能帮助我缩小我搞砸的地方.

更新:事实证明,将常规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.blit根本不起作用.

同样奇怪的是,一旦我尝试blit,然后绘制SOURCE fbo的纹理,它仍然全黑.这就像试图破坏一切废墟一样.

有人知道或有任何FBO blitting代码吗？我找不到任何东西,但我知道人们已经获得了多重采样FBO的工作.

以下是您可以提供帮助的方法:如果您有代码可以glBlitFramebuffer随时调用,我希望看到其他调用来设置该操作.一旦我调用它,我似乎无法得到任何东西,只有黑色缓冲区和纹理.

更新:Blit到backbuffer工作,即使是多重采样!这当然需要完全没有设置,因为我只是绑定帧缓冲区0.所以问题似乎是我设置的FBO,它有一个纹理附件,应该是blitting到.

Answer 1

事实证明，除了未能重置帧缓冲区绑定之外，我没有做任何错误。

最后void resolve_multisample_FBO()我只需要一个glBindFramebuffer(GL_FRAMEBUFFER, 0);

我向你保证，浪费 3 个小时真是太糟糕了。但多重采样看起来很棒，并且足以弥补这一点。