Circle Spiral
https://www.dwitter.net/d/20263
with(x)arc(960,540,t*t,(t%8>4?t:-t)/3,99),setLineDash([t*t/5]),stroke(),setLineDash([]),globalAlpha=1-S(t%4*.8),beginPath(stroke())
https://www.dwitter.net/d/20263
with(x)arc(960,540,t*t,(t%8>4?t:-t)/3,99),setLineDash([t*t/5]),stroke(),setLineDash([]),globalAlpha=1-S(t%4*.8),beginPath(stroke())