Light / dark backdrop affect

The backdrop becomes light, and then dark, and then light, dark, etc.

                                    ` This code was downloaded from The Game Creators
                                    ` It is reproduced here with full permission
                                    ` http://www.thegamecreators.com
                                    
                                    rem ****************************************************
rem ******************Backdrop Effect*******************
rem **********BY:*********MATTMAN***********************
rem ****************************************************
rem **********FOR:****20-Line Contest*******************
rem ****************************************************

rem Setup And Begin Loop
sync on : sync rate 0 : backdrop on : do 

rem Lighten
for x = 1 to 255 : color backdrop rgb(x,0,0) : wait 10 : sync : next x
rem Darken
for x = 1 to 255 : color backdrop rgb(255-x,0,0) : wait 10 : sync : next x

rem Lighten
for x = 1 to 255 : color backdrop rgb(0,x,0) : wait 10 : next x
rem Darken
for x = 1 to 255 : color backdrop rgb(0,255-x,0) : wait 10 : sync : next x

rem Lighten
for x = 1 to 255 : color backdrop rgb(0,0,x) : wait 10 : sync : next x
rem Darken
for x = 1 to 255 : color backdrop rgb(0,0,255-x) : wait 10 : sync : next x

rem Lighten
for x = 1 to 255 : color backdrop rgb(x,0,x) : wait 10 : sync : next x
rem Darken
for x = 1 to 255 : color backdrop rgb(255-x,0,255-x) : wait 10 : sync : next x

rem Lighten
for x = 1 to 255 : color backdrop rgb(0,x,x) : wait 10 : sync : next x
rem Darken
for x = 1 to 255 : color backdrop rgb(0,255-x,255-x) : wait 10 : sync : next x

rem End Loop
loop