> Say I have a `viewport' command. I start it this way: > > $ ./viewport > > A window opens. I go on typing in the shell: > > item1 0 0 1 0 1 1 0 1 0 0 > =2E.. To my understanding, this is more or less what you get with RenderMan. But there is another thing I forgot yesterday. OpenCascade. OC ships with a testing application. Its works exactly the way you descri= bed. When you start it from a shell, the graphic window opens. Then you can enter you commands into the shell. Like: "line myline1 0 0 0 10 10 10= ". The created entities appear in the graphic window. You can create curves, surfaces, topology, and apply lots of algorithms t= o the created entities. The graphic window can be edited also. You can pan, zoom, ...