--timer
t=0

function _update()
 --increase timer
 t+=0.05
end

function _draw()
 cls()

 --this crazy bit loops through
 --limited background colors,
 --and changes it when the
 --screen is covered with white
 local c = 12 + ((t-2.55)/4)%4
 rectfill(0,0,128,128,c)

 for i=0,8 do -- column loop
  for j=0,8 do -- row loop
  	--x positions are snapped
  	--to 16px columns
  	local x = i*16

  	--this number sweeps back
  	--and forth from -1 to 1
  	local osc1 = sin(t+i*0.1)

  	--this number also sweeps
  	--back and forth, but at
  	--a different rate
  	local osc2 = sin(t/4+j*0.03)

  	--y positions are influenced
  	--by one of the sweepy
  	--numbers
  	local y = j*16 + osc1*10

  	--the circles' radii are
  	--influenced by the other
  	--sweepy number
   circfill(x, y, osc2*15, 7)
  end
 end
end