function circ_rad(size) = size * sqrt(3) / 2;

function s2s_d4(size) = circ_rad(size)*4/sqrt(6);

function s2s_d6(size) = size;

function s2s_d8(size) = circ_rad(size)*2/sqrt(2);

function s2s_d12(size) = circ_rad(size)*4/(sqrt(3)*(1+sqrt(5)));