Xplot is an interactive 3D plotting program for X windows. It is capable of displaying simple objects that have easily described geometries. Currently, it only runs on 8bit pseudo color visuals. The way of using xplot is as follows. First one defines the object by specifying its geometry. Then plot it. Once an object is displayed on the screen, its appearance can be modified interactively by mouse input.
Docu: /usr/doc/X11-misc/xplot-beta-09feb95 & man xplot