The GNOME Project has deprecated the Clutter graphics library and has retired it from development. Starting with GNOME 42, the Clutter library and its associated components Cogl, Clutter-GTK, and Clutter-GStreamer will be removed from the GNOME SDK and their associated code moved to the archive repositories.
To maintain compatibility with existing extensions, GNOME Shell will retain internal copies of Cogl and Clutter and continue to ship for the foreseeable future. Developers of applications that use GTK3 along with Clutter, Clutter-GTK or Clutter-GStreamer are encouraged to migrate their programs to GTK4, libadwaita and GStreamer. If this is not possible, Cogl, Clutter, Clutter-GTK and Clutter-GStreamer should be separately added as dependencies to Flatpak packages, as they will be excluded from the main GNOME runtime.
The Clutter project has been in stagnation for a long time and is not developing - the last significant 1.26 release was formed in 2016, and the last corrective update was proposed in early 2020. The functionality and ideas developed in Clutter are now provided by the GTK4 framework, libadwaita, GNOME Shell, and the Mutter composite server.
Recall that the Clutter library is focused on providing rendering of the user interface. The functions of the Clutter library are focused on the active use of animation and visual effects, which allows you to apply the methods used in game development when creating ordinary GUI applications. At the same time, the library itself resembles a game engine, in which the maximum number of operations is carried out by the GPU, and a minimum of code is required to create a complex user interface. The library has mainly been used with OpenGL, but can also work on top of GLib, GObject, GLX, SDL, WGL, Quartz, EGL and Pango. There are bindings for Perl, Python, C#, C++, Vala and Ruby.
Source: opennet.ru