aUCBLogo Demos and Tests / moireepattern

to moireepattern
   singleshot=Name? "framenr
   N=1000   ;size and correspondingly the number of lines
   setUpdateGraph false
   PenUp
   hideTurtle
   perspective
   eye=Array (List 0 0 N)
   setEye eye {0 0 0}{0 1 0}
   running=true
   ifelse singleshot
   [   angle=framenr
   ][   angle=0
   ]
   while [running]
   [   clearScreen
      disableDepthTest
      moiree N angle angle/10
      angle=angle+0.1
      updateGraph
      if singleshot [break]
      if Key? [running=false]
   ]
end

to moiree N ang ang2
   bars N N/exp 1
   Home
   right ang
   up 90
   forward 100
   down 90+10+ang2
   bars N N/exp 1
end

to bars :size :num
   setPenSize [0 0]
   left 90+45
   forward :size/sqrt 2
   right 90+45
   repeat Int :num
   [   PenDown
      forward :size
      PenUp
      back :size
      right 90
      forward :size/(:num-1)
      left 90
   ]
end