GL_NV_copy_buffer
https://www.khronos.org/registry/OpenGL/extensions/NV/NV_copy_buffer.txt
GL_NV_copy_buffer

	GL_COPY_READ_BUFFER_NV 0x8F36
	GL_COPY_WRITE_BUFFER_NV 0x8F37
	void glCopyBufferSubDataNV (GLenum readtarget, GLenum writetarget, GLintptr readoffset, GLintptr writeoffset, GLsizeiptr size)