The COLOR Statement

Even though the computers used for Toy Story were much more expensive than ours, their computer graphics is fundamentally the same as ours:

• The graphics screen looks like graph paper.
• Each square of the graph paper (a pixel) has X and Y coordinates.
• Each pixel is set to a color.
• Digital images are made by setting the color of each pixel.

It would be awful if you had to say what color each and every pixel should be. So the graphics screen starts out black and you can set just the pixels you want. Here is an example program:

' Setting pixels to color 4
SCREEN 12
COLOR 4
PSET (3, 3) ' set column 3 row 3
PSET (7, 3) ' set column 7 row 3
PSET (7, 7) ' set column 7 row 7
PSET (3, 7) ' set column 3 row 7
END

If you run this program you will get four red dots in the upper left corner of the screen. The COLOR 4 statement picks the color to use (out of the 16 available.) It is like picking a colored pencil out of a box. Now four pixels are set (with PSET) to color 4. Here is what the picture will look like:

Here is what it looks like on the graphics screen:

(This picture has been enlarged to show the four tiny pixels.)