Python 使用PyQT5的OpenGL帧缓冲区屏幕外、屏幕上渲染问题

我正在尝试渲染到fbo以使用glReadPixels。我可以渲染到fbo并读取像素值，但我无法在屏幕上进行渲染，我遇到如下错误：

err=1286， description=b“无效的帧缓冲区操作”

以下是我的步骤：

    class MyGLWidget(QOpenGLWidget):
        ...
        ...
        def paintGl():
           ### offscreen rendering ###

           glBindFramebuffer(GL_FRAMEBUFFER, self.fbo);
           glClearColor(0.0, 0.0, 0.0, 1.0);
           glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    
           # ... bind texture ...
           # ... shader program...
           # ... VAO
           # ... EBO
           # ... uniforms
           # ... draw

           glBindFramebuffer(GL_FRAMEBUFFER, 0) #<--- The problem is here. i don't know why
    
           ### read pixel ###
           glBindFramebuffer(GL_READ_FRAMEBUFFER, self.fbo)
           glReadBuffer(GL_COLOR_ATTACHMENT0)
           print(glReadPixels(0, 0, _width, _height, _format, _type)) #<-- I got correct value here.

           ### on screen render ###
           glClearColor(0.0, 0.0, 0.0, 1.0) #<---I got an error here
           glClear(GL_COLOR_BUFFER_BIT)
    
           # ... bind texture (color attachment texture)
           # ... shader program...
           # ... VAO
           # ... EBO
           glDrawElements(mode, count, _type, indices)  #<--- If i don't use glClear, I get an error here.
           

类MyGLWidget（QOpenGLWidget）：
...
...
def paintGl（）：
###屏幕外渲染###
glBindFramebuffer（GL_FRAMEBUFFER，self.fbo）；
glClearColor（0.0,0.0,0.0,1.0）；
glClear（GL_颜色_缓冲_位| GL_深度_缓冲_位）；
# ... 绑定纹理。。。
# ... 着色器程序。。。
# ... 沃
# ... 埃博
# ... 制服
# ... 画
glBindFramebuffer（GLU帧缓冲区，0）#
glBindFramebuffer（GL\u帧缓冲区，0）#
glBindFramebuffer(GL_FRAMEBUFFER, 0) #<--- The problem is here. i don't know why