Thanks zep@lexaloffle for great examples!

Pico-8 Lua code by zep@lexaloffle:

r=64 t=0 ::a:: cls() for y=-r,r,3 do for x=-r,r,2 do z=cos(sqrt(x*x+y*y*2)/40-t)*6 pset(r+x,r+y-z,6) end end flip() t+=2/r goto a

TIC-80 Lua code by me:

-- title: `ripples` demo by zep@lexaloffle -- author: Al Rado 24.03.2017 -- desc: ported from Pico-8 =) -- script: lua -- pal: PICO8 r=120 t=0 function TIC() cls() for y=-r,r,3 do for x=-r,r,2 do z=cos(math.sqrt(x*x+y*y*2)/40-t)*6 pix(r+x,r+y-z-52,10) end end t=t+2/r end -- PICO-8 cos function cos(a) return math.cos(2*math.pi*a) end