A number of test meshes are contained in subdirectories of meshes . The script testscript subdivides them and writes them to corresponding output directories. The script testscript works only under Unix. The program subviewer is interactive. It takes a single command line argument, the name of the file containing a mesh, and displays two windows, one showing the result of applying the extended Catmull-Clark scheme to the mesh and the other the result of applying the extended Loop scheme to the same mesh.
Picking allows one to select edges, vertices and sectors and to apply, change and remove the tags.
In the examination mode, the arcball is used to change the camera position with respect to the mesh. Spacebar is used to switch between the two modes. In the examination mode, drag with the left mouse button pressed to rotate the surface, drag with the middle button pressed to translate it in a plane parallel to the screen, and with the left to move it perpendicular to the screen. The user can increase the subdivision level by pressing d , and write out the subdivided meshes by pressing s in the active window. The mesh with tags can be written with key w .