float diam=radius*2;
float s_eq[4]={ matrix[0]/diam, matrix[4]/diam, matrix[8]/diam, matrix[12]/diam+0.5 };
float t_eq[4]={ matrix[1]/diam, matrix[5]/diam, matrix[9]/diam, matrix[13]/diam+0.5 };
float diam=radius*2;
float s_eq[4]={ matrix[0]/diam, matrix[4]/diam, matrix[8]/diam, matrix[12]/diam+0.5 };
float t_eq[4]={ matrix[1]/diam, matrix[5]/diam, matrix[9]/diam, matrix[13]/diam+0.5 };