Mondrian

code:
/*
Mondrian Cube. MHC 2007.

Has a few rendering bugs...
*/
mondrian

rule mondrian {
  // The six faces of the cube
  a2
  { x -0.5 z -0.5 ry 90 } a2
  { x +0.5 z -0.5 ry 90 } a2
  { z -1 } a2
  { y +0.5 z -0.5 rx 90 } a2
  { y -0.5 z -0.5 rx 90 } a2
}

rule a2 w 2 maxdepth 2 > d {
  // Split into two halves in x direction
  { s 0.333 1 1 x -1 } a2
  { s 0.666 1 1 x 0.26 } a2
}

rule a2 w 2 maxdepth 2 > d {
  // Split into two halves in y direction
  { s 1 0.333 1 y -1 } a2
  { s 1 0.666 1 y 0.26 } a2
}

rule a2 { d }

// This rule chooses a random color.
rule d {
  { s 1 1 0.02 color #FF0000 } square
}

rule d {
  { s 1 1 0.02 color #0404A2 } square
}

rule d {
  { s 1 1 0.02 color #FFFE33 } square
}

rule d w 2 {
  { s 1 1 0.02 color #FFFFFF } square
}

// Draws a framed square
rule square {
  { s 0.95 0.95 1 } box
  { s 0.05 1.00 1 b 0 x -10 } box
  { s 0.05 1.00 1 b 0 x  10 } box
  { s 1.05 0.05 1 b 0 y -10 } box
  { s 1.05 0.05 1 b 0 y  10 } box
}