'Nirvana: all apologies
'by Mallard (mallard@gcomm.com)
'
'This program is also an example of error trapping to create continuous
'background music.
'It also does some stupid graphics-type stuff.
'
'Taken from:  The QBasic Page.  The best source for QB stuff on the 'net!
'http://www.wp.com/80948/qb/
'
SCREEN 13

PLAY "mb"

'defines music notes
'to change the music, switch the commented strings w/ the uncommented ones
'music1$ = "o2 f8 f8 f+8 f8 g+8 g+8 f+8 f4 f8 f+8 f8 o3 c#8 c#8 o2 b8 a#8"
'music2$ = "o2 f8 f8 f+8 f8 g+8 g+8 f+8 f4 f8 f+8 f8 o3 f8 f8 d#8 c#8"

PLAY "t255"
music1$ = "o2 c1 d4 f4 e4 d4 g2 g2 g4 a4 e4 f4 d2 d2 d4 f4 e4 d4 c4 o3 c4 o2 b4 a4 g4 f4 e4 d4 c1"
music2$ = "d4 f4 e4 d4 g2 g2 g4 a4 e4 f4 d2 d2 d4 f4 e4 d4 c4 g4 d4 e4 c2 p2"

'flag for which string of notes to play
mflag = 2
'flag for graphics
flag = 1
PLAY "mb"                                 'play music in background
PLAY music1$                              'begin music
PLAY ON                                   'enable PLAY error trapping


DO
ON PLAY(1) GOSUB playmusic                'if there's one note in the
                                          'music buffer, add the next notes
IF flag = 4 THEN flag = 1:                'sets flag
'graphics statements:
IF flag = 1 THEN LINE (INT(RND * 319) + 1, INT(RND * 200) + 1)-(INT(RND * 319) + 1, INT(RND * 200) + 1), PLAY(1), BF
IF flag = 2 THEN CIRCLE (INT(RND * 319) + 1, INT(RND * 200) + 1), PLAY(1), INT(RND * 15) + 1
IF flag = 3 THEN LINE (INT(RND * 319) + 1, INT(RND * 200) + 1)-(INT(RND * 319) + 1, INT(RND * 200) + 1), PLAY(1), B
LOOP

'SUB for music playing
'each plays its string, inverts the music flag, and increases the graphics
'flag.  Then they RETURN.
playmusic:
IF mflag = 1 THEN PLAY music1$: mflag = 2: CLS : flag = flag + 1: RETURN
IF mflag = 2 THEN PLAY music2$: mflag = 1: CLS : flag = flag + 1: RETURN


'End of program.  For more help on PLAY error trapping, write me at
'mallard@gcomm.com.