Smooth Animations Using Special Characters
The -charset- command is not limited to its use with foreign alphabets. Special characters are often used to create pictures:
The car is composed of several adjacent characters. Because characters can be drawn very fast (180 per second), dramatic animations are possible:
The car advances one dot at a time. If the car characters are designed in such a way as to leave a vertical column of blank dots at the back of the car, the “rewrite” mode will insure that the advancing car simultaneously erases its old position. If two columns are left blank, the car could be advanced two dots at a time and still completely wipe out the previous car display. This type of animation can run as fast as twenty or thirty moves per second, which creates the illusion of a smoothly moving object.
For the built-in characters there is an expandable and rotatable (but slow) line-drawn form available through the use of -size- and -rotate-, but these commands have no effect on charset characters. If a larger or rotated car is needed, it can be constructed with -draw- and -circle- commands, built up out of additional special characters, or produced with “lineset” characters. A lineset is like a charset, but the characters are made up of lines instead of dots. If “size” is not zero, and a lineset is in effect, alternate-font text is displayed as line-drawn characters which can be expanded and rotated.