glBindBuffer(GL_COPY_READ_BUFFER, old_buffer);
glBindBuffer(GL_COPY_WRITE_BUFFER, m_buffer_handle);
glCopyBufferSubData(GL_COPY_READ_BUFFER, GL_COPY_WRITE_BUFFER, 0, 0, m_buffer_size);
glBindBuffer(GL_COPY_READ_BUFFER, old_buffer);
glBindBuffer(GL_COPY_WRITE_BUFFER, m_buffer_handle);
glCopyBufferSubData(GL_COPY_READ_BUFFER, GL_COPY_WRITE_BUFFER, 0, 0, m_buffer_size);