7

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=%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);
}

你能看出我遗漏了什么吗？我认为问题可能出在glFramebufferRenderbuffer电话上。我尝试将第一个 arg 切换为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，肯定会失败并给我INVALID_ENUM或INVALID_OPERATION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，我必须更改的是在绘制时绑定 multi_fbo，然后调用将绑定和 blit 的解析函数。之后，我的 fbo 纹理（当我直接渲染到它时效果很好）现在应该包含多重采样渲染。但它只是黑色的。我还调用glEnable(GL_MULTISAMPLE)了初始化代码的另一部分。

我现在将尝试将非多重采样纹理blit 到另一个纹理以确保它有效。希望这将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（两者都具有附加到颜色附件 0 的纹理）会产生相同的黑屏。blit 根本行不通。

同样奇怪的是，一旦我尝试进行 blit，然后绘制 SOURCE fbo 的纹理，它仍然是全黑的。这就像试图破坏一切一样。

有人知道或有任何 FBO blitting 代码吗？我找不到任何东西，但我知道人们已经得到了多重采样 FBO 的工作。

以下是您可以提供帮助的方法：如果您有glBlitFramebuffer任何时候调用的代码，我希望看到其他调用来设置该操作。一旦我调用它，我似乎什么也得不到，除了黑色缓冲区和纹理。

更新：Blit to backbuffer 工作，即使是多重采样！这当然不需要任何设置，因为我只是绑定了帧缓冲区 0。所以问题似乎是我设置了 FBO，它有一个应该被 blitted 的纹理附件。

4

1 回答 1

4

事实证明，除了未能重置帧缓冲区绑定之外，我没有做错任何事情。

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

我向你保证，这是浪费 3 个小时的可怕方式。但是多重采样看起来很棒，而且弥补了它的不足。

于 2012-02-12T13:15:32.927 回答