Page 251 - Learn to Program - Basic-256

Chapter 16: Mathematics – More Fun With Numbers. Page 235

2 # rewrite of moveball.kbs using the modulo operator
to wrap the ball around the screen
3
4 print "use i for up, j for left, k for right, m for
down, q to quit"
5
6 fastgraphics
7 clg
8 ballradius = 20
9
10 # position of the ball
11 # start in the center of the screen
12 x = graphwidth /2
13 y = graphheight / 2
14
15 # draw the ball initially on the screen
16 call drawball(x, y, ballradius)
17
18 # loop and wait for the user to press a key
19 while true
20 k = key
21 if k = asc("I") then
22 # y can go negative, + graphheight keeps it
positive
23 y = (y - ballradius + graphheight) %
graphheight
24 call drawball(x, y, ballradius)
25 end if
26 if k = asc("J") then
27 x = (x - ballradius + graphwidth) % graphwidth
28 call drawball(x, y, ballradius)
29 end if
30 if k = asc("K") then
31 x = (x + ballradius) % graphwidth
32 call drawball(x, y, ballradius)
33 end if
34 if k = asc("M") then
35 y = (y + ballradius) % graphheight
36 call drawball(x, y, ballradius)

© 2019 James M. Reneau (CC BY-NC-SA 3.0 US)