Truchet

Truchet, then rotated 12

//https://en.wikipedia.org/wiki/Truchet_tiles

// try EOS, EPM, EPZ, AAZsa

startshape truchet4

CF::Impure = 1

CF::Symmetry = CF::Cyclic, 11 //  n-fold symmetry

xwide = 26

ytall    = xwide-1

shape truchet4 {

  loop i = xwide  [ ] {

    loop j = ytall  [ ] {

      tuch(i,j)[ rotate (0 )  ]

      }  

   }

}

  

shape tuch(number i  , number  j  ) {

   sq()  [x  (i +.5)   y (j) ]

    tr2(i,j)  [ x (i)  y (-0.5+ j) z 1 rotate 0  ]

    tr4 (i,j)  [ x (i)  y (-0.5+ j) z 4 rotate 0  ]

}

shape sq {

  SQUARE () [  h 0.00 sat 0.0000 b 0  ]

}

shape tr(xx,yy)

rule   { if (mod(xx,2) )  

              tr1 (xx,yy) [ s 1.0 z 3 ]

          else

             tr1(xx,yy) [ s 1.0 z 3 ] }

rule   { if (mod(xx,2) )  

             tr1 (xx,yy) [ s 1.0 z 3 ]

          else

             tr2(xx,yy) [ s 1.0 z 3 ] }

rule   {

          if (mod(xx,2) )  

             tr2 (xx,yy) [ s 1.0 z 3 ]

          else

             tr3(xx,yy) [ s 1.0 z 3 ]

          }

rule { if ( mod(xx,2)  )  

             tr3(xx,yy) [ s 1.0 z 3 ]

          else

             tr4(xx,yy) [ s 1.0 z 3 ] } 

path tr1(xx,yy) {

  MOVETO(0,0)

  LINETO(0,1)

  LINETO(1,1)

  LINETO(0,0)

  CLOSEPOLY()

  STROKE(.01)[]

  FILL()[ hue Colfunc(xx,yy)  sat (rand(1,10)*0.1) b 1.0  ]

}

path tr2(xx,yy)  {

  MOVETO(0,0)

  LINETO(1,1)

  LINETO(1,0)

  LINETO(0,0)

  CLOSEPOLY()

  STROKE(.01)[]

  FILL()[ hue  Colfunc(xx,yy)  sat (rand(1,10)*0.1) b 1.0  ]

}

path tr3(xx,yy)  {

  MOVETO(1,0)

  LINETO(1,1)

  LINETO(0,1)

  LINETO(1,0)

  CLOSEPOLY()

  STROKE(.01)[]

  FILL()[ hue  Colfunc(xx,yy)   sat (rand(1,10)*0.1) b 1.0  ]

}

path tr4(xx,yy) {

  MOVETO(1,0)

  LINETO(0,1)

  LINETO(0,0)

  LINETO(1,0)

  CLOSEPOLY()

  STROKE(.01)[]

  FILL()[ hue   Colfunc(xx,yy)    sat (rand(1,10)*0.1) b 1.0  ]

}

Colfunc(xx,yy) =    rand(xx*10, yy*10)