Usage examples
To clear the current depth buffer to a value typical of the far clipping
plane:
To discard all writes to the depth buffer (note that this will
also prevent clearing of the depth buffer):
To enable depth testing and set the depth function such that
only depth values less than the current value in the depth buffer will
be written:
Most of the functions raise exceptions if attempting to perform
operations on a framebuffer that does not have a depth buffer.