关于图形：glBlitFramebuffer导致OpenGL错误

glBlitFramebuffer cause OpenGL error

我想使用多重采样抗锯齿并保存我绘制到BMP的图像。我使用FBO进行多重采样和普通的FBO。我已经参考了本文：GL_framebuffer_multisample。

但是当我使用glBlitFramebuffer将数据从FBO进行多次采样复制到普通FBO时，就会发生OpenGL错误。现在我将部分代码发布在这里：

首先，创建两个FBO：

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glGenFramebuffers(1,&m_frameBuffer);
glBindFramebuffer(GL_FRAMEBUFFER,m_frameBuffer);

glGenRenderbuffers(1,&m_renderBufferColor);
glBindRenderbuffer(GL_RENDERBUFFER,m_renderBufferColor);
//在FBO里开启多重采样
glRenderbufferStorageMultisample(GL_RENDERBUFFER,4,
GL_RGB,m_subImageWidth,m_subImageHeight);
glFramebufferRenderbuffer(GL_FRAMEBUFFER,GL_COLOR_ATTACHMENT0,
GL_RENDERBUFFER,m_renderBufferColor);

glGenRenderbuffers(1,&m_renderBufferDepth);
glBindRenderbuffer(GL_RENDERBUFFER,m_renderBufferDepth);
glRenderbufferStorageMultisample(GL_RENDERBUFFER,4,
GL_DEPTH_COMPONENT24,m_subImageWidth,m_subImageHeight);
glFramebufferRenderbuffer(GL_FRAMEBUFFER,GL_DEPTH_ATTACHMENT,
GL_RENDERBUFFER,m_renderBufferDepth);

glBindFramebuffer(GL_FRAMEBUFFER,0);//解除绑定

//generate standard FBO for blitting
glGenFramebuffers(1,&m_frameBufferBlit);
glBindFramebuffer(GL_FRAMEBUFFER,m_frameBufferBlit);

glGenRenderbuffers(1,&m_renderBufferColorBlit);
glBindRenderbuffer(GL_RENDERBUFFER,m_renderBufferColorBlit);
glRenderbufferStorage(GL_RENDERBUFFER,GL_RGB,
m_subImageWidth,m_subImageHeight);
glFramebufferRenderbuffer(GL_FRAMEBUFFER,GL_COLOR_ATTACHMENT0,
GL_RENDERBUFFER,m_renderBufferColorBlit);

glGenRenderbuffers(1,&m_renderBufferDepthBlit);
glBindRenderbuffer(GL_RENDERBUFFER,m_renderBufferDepthBlit);
glRenderbufferStorage(GL_RENDERBUFFER,GL_DEPTH_COMPONENT24,
m_subImageWidth,m_subImageHeight);
glFramebufferRenderbuffer(GL_FRAMEBUFFER,GL_DEPTH_ATTACHMENT,
GL_RENDERBUFFER,m_renderBufferDepth);

glBindFramebuffer(GL_FRAMEBUFFER,0);//解除绑定

然后画点东西：

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glBindFramebuffer(GL_FRAMEBUFFER,m_frameBuffer);
GLenum status = glCheckFramebufferStatus(GL_FRAMEBUFFER);
if (status != GL_FRAMEBUFFER_COMPLETE)
{
cout <<"The frame buffer status is not complete!" << endl;
return;
}

drawing();//draw something
glBindFramebuffer(GL_FRAMEBUFFER,0);

int temp1 = GLUtils::checkForOpenGLError(__FILE__,__LINE__);
//blitting
glBindFramebuffer(GL_DRAW_FRAMEBUFFER,m_frameBufferBlit);
glBindFramebuffer(GL_READ_FRAMEBUFFER,m_frameBuffer);

int temp2 = GLUtils::checkForOpenGLError(__FILE__,__LINE__);
glBlitFramebuffer(0,0,m_subImageWidth,m_subImageHeight,
0,0,m_subImageWidth,m_subImageHeight,
GL_COLOR_BUFFER_BIT,GL_LINEAR);
int temp3 = GLUtils::checkForOpenGLError(__FILE__,__LINE__);
glBindFramebuffer(GL_READ_FRAMEBUFFER,0);
glBindFramebuffer(GL_DRAW_FRAMEBUFFER,0);

//glBindFramebuffer(GL_FRAMEBUFFER,m_frameBuffer);
glBindBuffer(GL_PIXEL_PACK_BUFFER,m_subImageBuffer[i]);
glPixelStorei(GL_PACK_ALIGNMENT,1);

glBindFramebuffer(GL_FRAMEBUFFER,m_frameBufferBlit);
//注意：以BGR的顺序读取
glReadPixels(0,0,m_subImageWidth,m_subImageHeight,
GL_BGR,GL_UNSIGNED_BYTE,bufferOffset(0));
int temp4 = GLUtils::checkForOpenGLError(__FILE__,__LINE__);
m_subPixels[i] = static_cast<GLubyte*>(glMapBuffer(GL_PIXEL_PACK_BUFFER,GL_READ_ONLY));
if (m_subPixels[i] == NULL)
{
cout <<"NULL pointer" << endl;
}
gltGenBMP(subImageFile[i],GLT_BGR,m_subImageWidth,m_subImageHeight,m_subPixels[i]);
glUnmapBuffer(GL_PIXEL_PACK_BUFFER);
glBindBuffer(GL_PIXEL_PACK_BUFFER,0);

glBindFramebuffer(GL_FRAMEBUFFER,0);

函数GLUtils :: checkForOpenGLError用于检查是否发生OpenGL错误(返回1表示发生了错误)绘图是用于渲染某些东西，而gltGenBMP函数是将数据另存为BMP，它们都工作良好，我发现temp1和temp2为0，temp3和temp4为1.所以我得出一个结论：glBlitFramebuffer函数有问题，但为什么设置有问题？

更新：
当我检查正常的FBO m_frameBufferBlit时：

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glBindFramebuffer(GL_DRAW_FRAMEBUFFER,m_frameBufferBlit);
status = glCheckFramebufferStatus(GL_DRAW_FRAMEBUFFER);
if (status != GL_FRAMEBUFFER_COMPLETE)
{
cout <<"The frame buffer status is not complete!" << endl;
return;
}

我发现它不完整。所以我没有正确创建FBO吗？

有什么问题？