How could I attach window-system-provided “depthbuffer” to application-created framebuffer object like this.
glFramebufferRenderbuffer( GL_FRAMEBUFFER , GL_DEPTH_ATTACHMENT , GL_RENDERBUFFER , window-system-provided-depthBuffer );
I read the spec doc as follow.( http://www.opengl.org/registry/specs/EXT/framebuffer_object.txt )
By default, the GL uses the window-system-provided framebuffer. The
storage, dimensions, allocation, and format of the images attached
to this framebuffer are managed entirely by the window-system.
Consequently, the state of the window-system-provided framebuffer,
including its images, can not be changed by the GL, nor can the
window-system-provided framebuffer itself, or its images, be deleted
by the GL.
I wonder about the possibility of this.