// tiling pattern in the xz plane  
pigment{
           tiling 23 // 1~24 Pattern_Number
              color_map{
                [ 0.0 color rgb<1,1,1>*1]
                [ 0.5 color rgb<1,0.5,0>*1]
                [ 1.0 color rgb<1,1,1>*0]
                } // end color_map
           scale 0.5
           // rotate<-90,0,0> // align to xy plane
        } // end pigment
 