Using Change-Sets to Achieve a Bounded Undo and Make Tutorials in 3D Version Control Systems.

A system that records changes made to a file is called a Version Control System (VCS). Even thought VCSs may store all kind of files, we focus on changes made to polygonal meshes files. Our method allows the user to track the history of topological and geometrical changes to part of a model. This part is selected through a bounding box selection mechanism, and the user can track the change-sets of the selected mesh subset, i.e., the user can see the difference between any consecutive versions of the modeling sequence. With that mechanism, it is possible to construct a sub-tree associated with the selected region to serve as a tutorial on how that part was modeled. That sub-tree also allows the user to undo local changes that do not propagate to the whole mesh. That, so called, bounded undo is an important feature of our method. Despite the important contributions, we also point out some current limitations to our method and discuss ways that might overcome them.