傘の親骨の形状をＣＳＧの結合により生成します。
//**********************************************************************************
#local Rib_seg = union {
torus { 1, Wr/5 clipped_by { plane { z, 0 translate -0.63*z } } }
cylinder { 0*z, 0.01*z, Wr/5 rotate -40*y translate <-0.78,0,-0.63> }
cylinder { 0*z, 0.01*z, Wr/5 rotate 40*y translate <0.78,0,-0.63> }
pigment { color rgb <1,0,0> } scale <0.997,1,1> translate Wr/5*z }
#local Rib = union { #local N=0; #while( N < Nmax/2 )
object { Rib_seg rotate N*360/Nmax*z} #local N=N+1; #end }
//**********************************************************************************
