Sketchpad Redux

A re-creation of Ivan Sutherland’s Sketchpad · TX-2 · 1963

Push buttons

Knobs

Horiz
Vert
Scale
Rotate

Pen aimed at

Picture

Points
0
Lines
0
Arcs
0
Scale
1.0×

Saved

Working the console

Sketchpad was worked with two hands: a light pen in one, push buttons under the other. Here the mouse or a stylus is the pen, and the keys are the buttons. Here your finger is the pen.

The pen

  • The cross follows the pen. The bright dot is where the pen “really” is: it jumps onto a point, line or arc when you come near one. Everything happens at the dot.
  • Two hands are quickest: hover over the display and press the keys. Click a button instead and its lamp blinks: it waits for you to click on the display where it should act. Whatever you were carrying stays where you left it.
  • To put down what the pen is carrying: click, push STOP (Esc), or right-click.

Drawing

  • Lines: aim, push DRAW (D). The line’s end rides on the pen. Push DRAW again to fix it there and start the next line; put it down to finish.
  • Closing a shape: bring the last end back onto the first point and put it down. The ends merge, and the corners are shared.
  • Arcs and circles: aim at the center and push CIRCLE CENTER (C); an × marks it. Click where the arc should start, swing round the center, and click to end. Go all the way round for a full circle.
  • Moving: aim, push MOVE (M), put it down. Move a corner and every line on it follows. Put a point down on another point and they merge. While carrying a line or arc, the ROTATE knob turns it.
  • Deleting: aim, push DELETE (X). Deleting a point deletes the lines and arcs on it. DELETE PICTURE erases everything: push it twice.

The window

  • The knobs move and magnify the window: drag around them, scroll over them, or focus one and use the arrow keys.
  • Or: scroll to move, pinch or Ctrl/⌘-scroll to magnify, arrow keys to move, + − to magnify, 0 to go home.

The pen

  • Touch the display and the pen goes there; drag and it follows. Near a point, line or arc it locks on, with a buzz where your device can. Everything happens where it locks.
  • Buttons wait for you: tap one and its lamp blinks, then tap the display where it should act, or press there and drag.
  • To put down what the pen is carrying, lift your finger.

Drawing

  • Lines: tap DRAW, then press where the line starts and drag to where it ends. To keep going, tap DRAW and start from the last end.
  • Closing a shape: end the last line on the first point. The ends merge, and the corners are shared.
  • Arcs and circles: tap CIRCLE CENTER, then tap the center; an × marks it. Press where the arc starts and drag round the center; lift to end. Go all the way round for a full circle.
  • Moving: tap MOVE, then press on a point, line or arc and drag it. Move a corner and every line on it follows. Drop a point on another and they merge.
  • Deleting: tap DELETE, then tap what to delete. Deleting a point deletes the lines and arcs on it. DELETE PICTURE erases everything: tap it twice.

The window

  • Pinch on the display to magnify, and drag with two fingers to move the window. Or turn the knobs.

There is no undo, just as in 1963. Your drawing saves itself in this browser.

Sketchpad Redux

About Sketchpad

Install Sketchpad Redux

Installed, it opens in a window of its own and works offline.

Tap the Share button, then Add to Home Screen. In Safari, Share is in the toolbar; in Chrome, it’s in the address bar or the ⋯ menu.

Choose File › Add to Dock.

Open your browser’s menu and choose Install or Add to Home screen.