How TeX Calculates Glue Settings in an \hbox
This is the third, and concluding, article in a series which takes a look at TeX boxes and glue. The first post Boxes and Glue: A Brief, but Visual, Introduction Using LuaTeX introduced the concepts of boxes and glue and was followed by Pandora’s \hbox: Using LuaTeX to Lift the Lid of TeX Boxes which presented a LuaTeX-based Overleaf project to explore the deeper structures of TeX boxes through the use node graphs. In this final piece we take a “deep dive” into the mechanics of how TeX calculates glue values in an \hbox: a process referred to as setting the glue. We make extensive use of node graphs (introduced in the second article in this series) and show how to use and interpret some of the data they provide: glue_set, glue_sign and glue_order.