$pattern tri period

The pattern tri period is the same definition in pattern type as the

$pattern_tri_period
pattern_tri_num
pattern_type N_period period_space $x_1$ $y_1$  $x_2$ $y_2$  $x_3$ $y_3$  $n_r$ $\alpha$ if_empty

For a triangular shape, we need 3 points (x1,y1), (x2,y2), and (x3,y3) to define the triangular shape. Then the refractive index and the absorption coefficient is put in the simulation.