ColorSample(x, y)
: if a == (0, 0.17) rel (x, y)
   , b == (0, 0.5) rel (x, y)
   , c == (0, 0.83) rel (x, y)
   , d == (0.33, 0) rel (x, y)
   , e == (0.33, 0.2) rel (x, y)
   , f == (0.33, 0.4) rel (x, y)
   , g == (0.33, 0.6) rel (x, y)
   , h == (0.33, 0.8) rel (x, y)
   , i == (0.33, 1.) rel (x, y)
   , j == (0.66, 0) rel (x, y)
   , k == (0.66, 0.2) rel (x, y)
   , l == (0.66, 0.4) rel (x, y)
   , m == (0.66, 0.6) rel (x, y)
   , n == (0.66, 0.8) rel (x, y)
   , o == (0.66, 1.) rel (x, y)
   , p == (1., 0) rel (x, y)
   , q == (1., 0.2) rel (x, y)
   , r == (1., 0.4) rel (x, y)
   , s == (1., 0.6) rel (x, y)
   , t == (1., 0.8) rel (x, y)
   , u == (1., 1.) rel (x, y)
   | T
  -> black paint 
     c1(a)
   ; white paint 
     c1(b)
   ; grey paint 
     c1(c)
   ; red paint 
     c1(d)
   ; blue paint 
     c1(e)
   ; green paint 
     c1(f)
   ; yellow paint 
     c1(g)
   ; cyan paint 
     c1(h)
   ; magenta paint 
     c1(i)
   ; darkred paint 
     c1(j)
   ; darkblue paint 
     c1(k)
   ; darkgreen paint 
     c1(l)
   ; darkyellow paint 
     c1(m)
   ; darkcyan paint 
     c1(n)
   ; darkmagenta paint 
     c1(o)
   ; lightred paint 
     c1(p)
   ; lightblue paint 
     c1(q)
   ; lightgreen paint 
     c1(r)
   ; lightyellow paint 
     c1(s)
   ; lightcyan paint c1(t); lightmagenta paint c1(u) fi

  OrthoBasis(center, u, v)
: if minuss == (- 1, 0) rel (center, v)
   , minusx == (- 1, 0) rel (center, u)
   , sx == (0, 0) rel (center)
   , ws == (0, 0) rel (center)
   , w == (0, - 1) rel (center, u)
   , vz == (0, 0) rel (center)
   , wz == (0, - 1) rel (center, u)
   , z == (0, - 1) rel (center, u)
   , uypr == (0, 0.5) rel (center)
   , ux == (0, 0) rel (u)
   , vs == (0, 0) rel (v)
   , x == (0, 0) rel (u)
   , s == (0, 0) rel (v)
   , uy == (0, 0) rel (center)
   , sy == (0, 0) rel (v)
   , y == (0, 0) rel (v)
   | (center, x) para (center, minusx)
 and (center, x) cong (center, minusx)
 and (center, ux) para (center, x)
 and hor (u, ux)
 and (center, sx) para (center, minusx)
 and hor (s, sx)
 and hor (y, center)
 and hor (uy, center)
 and (u, uy) para (x, center)
 and ver (center, uypr)
 and (center, uypr) cong (center, uy)
 and (uypr, sx) cong (center, y)
 and hor (sy, center)
 and (sy, s) para (x, center)
 and (center, s) para (center, minuss)
 and (center, s) cong (center, minuss)
 and (y, x) para (sy, ux)
 and (y, minusx) para (uy, sx)
 and (s, center) para (vs, center)
 and (s, center) para (center, ws)
 and (wz, w) para (center, minuss)
 and (center, minuss) para (v, vz)
 and (s, z) para (wz, vs)
 and (z, minuss) para (vz, ws)
 and (y, center) cong (z, center)
 and ver (center, z)
 and ver (vs, v)
 and ver (center, vz)
 and ver (center, wz)
 and ver (ws, w)
  -> Squaredot(x)
   ; Squaredot(z)
   ; Squaredot(y)
   ; Dots(u, ux)
   ; Dots(u, uy)
   ; Dots(sy, s)
   ; Dots(s, sx)
   ; Dots(v, vs)
   ; Dots(v, vz)
   ; Dots(wz, w)
   ; Dots(w, ws)
   ; Platch(v)
   ; Platch(w)
   ; Platch(u)
   ; draw (center, x)
   ; draw (center, z)
   ; draw (center, y)
   ; draw (center, u)
   ; draw (center, s)
   ; draw (center, v)
   ; draw (center, minuss)
   ; draw (center, minusx)
   ; draw (center, w) fi

  FalsePerspTest(c, u, v)
: if r == (0, 1) rel (c, u)
   , minusr == (- 1, 0) rel (c, u)
   , q == (- 1, 0) rel (c)
   , p == (0, 1) rel (c)
   , ur == (0, 0.5) rel (c, u)
   , uq == (- 0.5, 0) rel (c)
   , m == (0, 1) rel (c, u)
   , minusm == (0, - 1) rel (c, u)
   , mq == (- 0.5, 0) rel (c)
   , mr == (- 0.5, 0) rel (c, u)
   , w == (0, 0) rel (c)
   , vm == (- 0.5, - 0.5) rel (c)
   , vp == (0, 0.5) rel (c)
   , wm == (0.5, 0.5) rel (c)
   , wp == (0.5, 0.5) rel (c)
   | ver (c, p)
 and hor (c, q)
 and (c, p) cong (c, q)
 and (c, r) para (c, minusr)
 and (c, r) cong (c, minusr)
 and hor (uq, c)
 and (ur, c) para (r, c)
 and hor (mq, c)
 and (mr, c) para (r, c)
 and (ur, u) para (c, q)
 and (uq, u) para (c, r)
 and (ur, mq) para (r, q)
 and (uq, mr) para (q, minusr)
 and (vm, c) para (m, c)
 and ver (vp, c)
 and ver (wp, c)
 and (m, c) para (wm, c)
 and (v, vp) para (m, c)
 and ver (v, vm)
 and ver (w, wm)
 and (w, wp) para (c, m)
 and (vm, vp) para (m, p)
 and (m, c) para (minusm, c)
 and (m, c) cong (minusm, c)
 and (wm, wp) para (p, minusm)
  -> Blah fi

  Blah(Args)
: round ends 
  stroke (v, v)
; print(" v", v, "TimesRoman", 10, 0)
; stroke (u, u)
; print(" u", u, "TimesRoman", 10, 0)
; stroke (w, w)
; print(" w", w, "TimesRoman", 10, 0)
; red paint 
  stroke (p, p)
; print(" p", p, "TimesRoman", 10, 0)
; stroke (q, q)
; print(" q", q, "TimesRoman", 10, 0)
; stroke (r, r)
; print(" r", r, "TimesRoman", 10, 0)
; stroke (m, m)
; print(" m", m, "TimesRoman", 10, 0)