freeglut3-dev binary package in Ubuntu Focal i386

 GLUT is a window system independent toolkit for writing OpenGL programs.
 It implements a simple windowing API, which makes learning about and
 exploring OpenGL programming very easy.
 .
 GLUT is designed for constructing small to medium sized OpenGL programs,
 however it is not a full-featured toolkit, so large applications requiring
 sophisticated user interfaces are better off using native window system
 toolkits like GTK+ or Motif.
 .
 This package contains libraries, and headers suitable for software
 development with GLUT.

Source package