Sketchpad: A Man-Machine Graphical Communication System Alive

Running on MIT's TX-2, Sketchpad let users draw on a CRT with a light pen — constraints propagated through drawings, objects could be instantiated and edited as masters, and rubber-band lines snapped to geometry. It contained in embryo object orientation, parametric CAD, and direct manipulation.

Sutherland's 1963 thesis and its films spread through the research community; Ivan himself moved on to head-mounted displays and Evans & Sutherland. Nearly every graphics and UI system since descends from ideas first demonstrated in this one program.