Fix a bug in rotational periodic boundary conditions

[GuySten]

Description

This PR simplify and fix logic of periodic boundary conditions.
It prevents particles getting lost when the periodic surfaces have normals in any direction.
I also added tests that check that the code run correctly regardless of the periodic plane normal direction.

Checklist

• I have performed a self-review of my own code
• I have run clang-format (version 15) on any C++ source files (if applicable)
• I have followed the style guidelines for Python source files (if applicable)
• I have made corresponding changes to the documentation (if applicable)
• I have added tests that prove my fix is effective or that my feature works (if applicable)

[paulromano]

Thanks for this fix and simplification! The one thing that still doesn't seem quite right is the warning about the angle not evenly subdividing 360. Depending on the orientation of the surfaces and whether positive/negative half-spaces are used to define the region, sometimes that warning is shown even when the angle is fine. To illustrate that, I've put together this example with two planes that are created using Plane.from_points, where each set of three points is randomly permuted. The region being plotted is the same in each case but some permutations of the points end up with the warning and some don't.

import openmc
from math import cos, sin, pi, radians
import numpy as np
import random

start = 0.
degrees = 45.
ang1 = radians(start)
ang2 = radians(start + degrees)

p1_points = [(0., 0., 0.), (cos(ang1), sin(ang1), 0.), (0., 0., 1.)]
p2_points = [(0., 0., 0.), (cos(ang2), sin(ang2), 0.), (0., 0., 1.)]
random.shuffle(p1_points)
random.shuffle(p2_points)

p1 = openmc.Plane.from_points(*p1_points, boundary_type='periodic')
p2 = openmc.Plane.from_points(*p2_points, boundary_type='periodic')
p1.periodic_surface = p2
zcyl = openmc.ZCylinder(r=5., boundary_type='vacuum')

# Figure out which side of planes to use based on a point in the middle
ang_mid = radians(start + degrees/2.)
mid_point = (cos(ang_mid), sin(ang_mid), 0.)
r1 = -p1 if mid_point in -p1 else +p1
r2 = -p2 if mid_point in -p2 else +p2

(r1 & r2 & -zcyl).plot()

[GuySten]

In my testing, the normalization of the angle range to [-PI,PI] fix the warning problem.