to rotmetal WindowMode clearScreen hideTurtle PenUp right 180 forward 50 left 180 PenDown setPenSize [.5 .5] setPenColor rgba 0 0 0 4/256 for [i 1 255] [ for [j 1 255] [ setPenColor rgba i/512 (mod j*i 255)/512 j/512 4/256 square 100 forward 0.05 right 0.01*i ] forward 25 left 1 updateGraph if Key? [stop] ] print [OK] end to diagonal size PenUp right 45 forward size*sqrt 2 right 135 PenDown end to square size diagonal size/2 repeat 4 [ forward size right 90 ] diagonal size/2 end