$pattern tri region

$pattern_tri_region
pattern_tri_num
$x_{1}$ $y_{1}$  $x_{2}$ $y_{2}$  $x_{3}$ $y_{3}$  $n_{r}$ $\alpha$ 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.