var arr_s2 = [],
arr_s = [],
colour_positions = [],
colour_values = [],
thickness_positions = [],
thickness_values = [],
//change the values of the following five variables to change the grid size
//change the values of the following five variables to change the grid size
x_limit_1 = -10,
x_limit_2 = 10,
y_limit_1 = 5,
y_limit_2 = 30,
z = -4, //perpendicular distance of the grid from the XY plane
sc = 100,
x_inc = 5,
y_inc = 5,
z_inc = 5,