UI
PRINT
":1'
20
FOR
T-38400
TO
38421
30
POKE
T,6:NE~T
40
FOR
T-7680
TO
7701
58
FOR
Y-e
TO
10:NE~T
60
POKE
T-l,
32:POKE
T,81:~T
70
FOR
T-7701
TO
7680
STEP
-1
80
FOR
Y-0
TO
10:NE~T
90
POKE
T+l,32:
POKE
T,81:
NEXT
100
OOTO
40
Chapter
7:
Sound 247
Now
we
will add sound with the following lines:
15
POI<E
36878,
15
6S
POKE
36876,248:
POKE
36876,0
95
POKE
36876,230:
POKE
36876,8
The addition
of
sound helps create the effect
of
a bouncing ping-pong ball.
To
synchronize the sound with a visual event
on
the screen, you will
have
to
be aware
ofthe
position
ofthe
objects
on
the screen.
In
the example
above, the timing was straightforward because the sound was created
at
the
end
of
each loop.
To
make simple sounds synchronize with movements, the
sounds should generally take place when one object collides with another.
The following program determines object movement and sound based
on
the numeric position
on
the screen:
10
POKE
36878,15:
R
a
l:
RT-.7:
PRINT
":']"
20
FOR
T-38400
TO
38421:
POKE
T,5:NEXT
30
FOR
T
a
38422
TO
38443:POKE
T,6:NEXT
40
T-7680:
TT-7702
50
POKE
T,SI:POKE
T-l,32:POKE
T+l,32
60
POKE
TT,81:
POKE
TT-l,32:
POKE
1T+l,32
70
T-T+R:
TT-TT+RT
S0
IF
T-7680
OR
T-7701
THEN
R-R*-1
90
IF
TT)7723
OR
T(7702
THEN
RT-RT*-l
1.00
OOTO
50
Because different tone values are used, it
is
immediately apparent which
object has just hit the wall.
Tailoring
the
Sound
to
The
Picture
Now let's look
at
some exploding ping-pong balls. The next program
will take
our
familiar ping-pong sound and combine it with a picture. After a
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