Commodore Plus 4 - Page 95

CHARACTER Movies are really a sequence of still pictures. Each picture is a little
ANIMATION different from the one tnat came before. The projector shows each
picture for a very short time, then goes on to the next one. The scene
becomes animated.
Computer animation works the same way. First the computer draws
one picture, then it changes the picture slightly. The Plus/4 is fast
enough to allow objects to move smoothly all around the screen in
your games and practical programs.
You can't type fast enough to create animation. A movie is animated
at a rate of 30 pictures per second. The changes must be fast enough
to fool the eye. So you must use a program to draw a picture, wait for
a split second, then change to a new picture.
To get the program to create pictures we use the PRINT statement with
the graphic characters. The simplest type of animation involves alter
nating two characters to get the effect of movement.
This program simulates the movement of a pulsing ball.
Type NEW and press RETURN before entering each new program.
Remember to press RETURN after each line in all these programs.
10 PRINT" HOME
20 FOR L = l TO 100
30 NEXT L
40 PRINT" HOME
50FORL = lTO100
60 NEXT L
70 GOTO 10
SHIFT Q"
SHIFT
Type these keys
simultaneously
Type RUN and press RETURN
To get a more interesting effect you can build a small picture from
several graphic characters, then change a few of the characters
while leaving others in the same place. This gives the effect of part
of an object moving, demonstrated in the following program.
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