GLsync new_data_ready_fence; // Whether new_frame is ready for rendering.
std::condition_variable new_data_ready_changed; // Set whenever new_data_ready is changed.
unsigned dropped_frames = 0; // Before new_frame.
GLsync new_data_ready_fence; // Whether new_frame is ready for rendering.
std::condition_variable new_data_ready_changed; // Set whenever new_data_ready is changed.
unsigned dropped_frames = 0; // Before new_frame.