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History of Computer Graphics

he advance in computer graphics was to come from one MIT student, Ivan Sutherland.
In 1961 Sutherland created another computer drawing program called Sketchpad.
TUsing a light pen, Sketchpad allowed one to draw simple shapes on the computer
screen, saved them and even recalled them later. The light pen itself had a small photoelectric
cell in its tip. This cell emitted an electronic pulse whenever it was placed in front of a
computer screen and the screen’s electron gun fired directly at it. By simply timing the
electronic pulse with the current location of the electron gun, it was easy to pinpoint exactly
where the pen was on the screen at any given moment. Once that was determined, the
computer could then draw a cursor at that location.
Sutherland seemed to find the perfect solution for many of the graphics problems he faced.
Even today, many standards of computer graphics interfaces got their start with this early
Sketchpad program. One example of this is in drawing constraints. If one wants to draw
a square for example, s/he does not have to worry about drawing four lines perfectly to
form the edges of the box. One can simply specify that s/he wants to draw a box, and then
specify the location and size of the box. The software will then construct a perfect box, with
the right dimensions and at the right location. Another example is that Sutherland’s software
modeled objects - not just a picture of objects. In other words, with a model of a car, one
could change the size of the tires without affecting the rest of the car. It could stretch the
body of the car without deforming the tires.

These early computer graphics were Vector graphics, composed of thin lines whereas modern
day graphics are Raster based using pixels. The difference between vector graphics and raster
graphics can be illustrated with a shipwrecked sailor. He creates an SOS sign in the sand
by arranging rocks in the shape of the letters “SOS.” He also has some brightly coloured
rope, with which he makes a second “SOS” sign by arranging the rope in the shapes of the
letters. The ropk SOS sign is similar to raster graphics. Every pixel has to be individually
accounted for. The rope SOS sign is equivalent to vector graphics. The computer simply sets
the starting point and ending point for the line and perhaps bends it a little between the two
end points. The disadvantages to vector files are that they cannot represent continuous tone
images and they are limited in the number of colours available. Raster formats on the other
hand work well for continuous tone images and can reproduce as many colours as needed.

Also in 1961 another student at MIT, Steve Russell, created the first video game, Spacewar.
Written for the DEC PDP-1, Spacewar was an instant success and copies started flowing to
other PDP-1 owners and eventually even DEC got a copy. The engineers at DEC used it as
a diagnostic program on every new PDP-1 before shipping it. The sales force picked up on
this quickly enough and when installing new units, would run the world’s first video game
for their new customers.
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