// ps 2-7 // one steadily paces around the perimeter, // the other hops from corner to corner. // if you keep watching this long enough, // the lines will disappear into fog. set z 100 pen 0 repeat b 0 20 { set z (100-b*5) repeat a (-100) (-50) { paper z line (a*a*a*a/1000000) (a*a/100) (a*a*a*a/1000000+10) (a*a/100) line ((a+100)*2) 100 (2*(a+100)) 90 } repeat a (-50) 0 { paper z line (a*a*a*a/1000000) (a*a/100) (a*a*a*a/1000000+10) (a*a/100) line 100 ((0-a)*2) 100 (2*(0-a)-10) } repeat a 0 50 { paper z line (a*a*a*a/1000000) (a*a/100) (a*a*a*a/1000000+10) (a*a/100) line (100-a*2) 0 (100-2*a) 10 } repeat a 50 100 { paper z line (a*a*a*a/1000000) (a*a/100) (a*a*a*a/1000000+10) (a*a/100) line 0 (2*(a-50)) 0 (2*(a-50)-10) } }