Commodore CBM - Animation; Time Delay

ANIMATION
Animation on the PET is done in program mode. Any graph, number,
design, word,
or pieture may be programmed to move sideways, up, down, or
diagonally, flash on and off, print faster or slower, in almost any eombination.
Animation is a capability that distinguishes the PET from many other computers.
and it will probably be the most fun aspect for vou.
To demonstrate animation.
we will begin by animating the sketching of the
small square programmed in the previous section (see page 5-95 for final listing).
Instead of seeing the square appear instantaneously on the sereen, animation
will allow the viewer to wateh eaeh element of the square slowly appear on
the sereen.
The program to animate the square looks very different from the previous
program because the line segments are programmed in BASIC code and
not as
picture segments. There is no large square within quotation marks. The square is
broken down into individual graphie characters.
TIME DELAY
The purpose of the animated program is to slowly move the eursor 50
we ean see the lines of the square being printed eloekwise from the top left
corner of the screen.
The first step.
as always, is to clear the screen. This also puts the cursor in
the home position.
5 F'RH~T":"l".;
The second step is to type the top left corner. However, do not draw the
whole top line as vou did in the previous program. just the corner.
1(1 F'RI tiT "r" .;
ln order to see eaeh element of the square being printed, it is neeessary
to slow down the normal PET print speed. This ean be done by using a time
delay loop,
similar to this statement 100:
100 FOR 3=1 TO 10'NEXT 3:RETURN
The FOR ... NEXT loop increases the time between the printing of each character. It
forces the PET to count from 1 to 10 each time the subroutine is ca lied. While the
PET is counting it cannot execute other statements or print thus it is delayed from
printing the next character and its print speed appears slower. The
Ta index for J
can be increased or decreased to lengthen or shorten the delay. The larger the Ta
index for J is set the longer the time between printing each character.
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