Question

我正在尝试将多重采样场景渲染为纹理，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？我认为问题可能出在glFramebufferRenderbuffer电话上。我尝试将第一个arg切换到GL_READ_FRAMEBUFFER，但它没有修复。

我检查glGetError并且没有错误。如果我设置错误，肯定有些事情会失败并给我INVALID_ENUM或INVALID_OPERATION来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。我也在初始化代码的另一部分中调用了glEnable(GL_MULTISAMPLE)。

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。

以下是您可以提供的帮助： 如果您的代码在任何时候都有glBlitFramebuffer，我希望看到其他调用来设置该操作起来。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 to 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。

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

浪费3个小时的可怕方式，我向你保证。但是多重采样看起来很棒，而不仅仅是弥补它。

FBO Blitting无效

1 个答案: