01Overview

In 1963 Sutherland’s doctoral thesis demonstrated Sketchpad: draw lines and circles on a CRT with a light pen, keep geometric relations through constraint solving, and copy, scale and even simulate physics. It is regarded as the beginning of interactive computer graphics and of CAD.

Sketchpad mattered beyond drawing: it showed a person could hold a conversation with a computer by direct manipulation instead of submitting batch jobs. Constraints, objects, primitives and views entered every graphics system afterwards. Sutherland went on to ARPANET and virtual reality, pressing the same idea of human–computer symbiosis.

02History

  1. 1963

    Sketchpad

    Interactive graphics and constraint solving.

  2. 1964

    Sutherland joins ARPA

    He pushes graphics and networking research.

  3. 1968

    The HMD paper

    An early vision of virtual reality.

03Core concepts

Direct manipulation

The user acts on objects on screen and sees the result immediately.

Constraint solving

Maintain relationships between shapes through geometric constraints.

Light pen

An early on-screen pointing device.

04Hands-on

Do it once — it beats reading it ten times

Build a tiny constraint solver: two segments that must stay perpendicular while you drag one endpoint

05Self-check

Say it in your own words first, then open the answer. Whatever you cannot explain is what to review next.

Can you explain "Direct manipulation"?

The user acts on objects on screen and sees the result immediately.

Can you explain "Constraint solving"?

Maintain relationships between shapes through geometric constraints.

Can you explain "Light pen"?

An early on-screen pointing device.

What problem did it solve, and why was there nothing better at the time?

Go back to the history section: how was this done before, and what did it cost?

If you had to build it today, how would you break it down?

Use the hands-on task above: write a plan of at most three steps before you start.

06Key people

I

Ivan Sutherland

1938 –

A pioneer of Sketchpad and head-mounted displays.

D

Douglas Engelbart

1925 – 2013

Inventor of the mouse and of hypertext.

07Further reading

  • Sketchpad: A Man-Machine Graphical Communication SystemIvan Sutherland · 1963
  • Man-Computer SymbiosisJ. C. R. Licklider · 1960