Unit test to verify that photons at normal incidence do not abort.

1 files changed, 53 insertions, 0 deletions

diff --git a/tests/propagation.py b/tests/propagation.py
new file mode 100644
index 0000000..331242b
--- /dev/null
+++ b/tests/propagation.py
@@ -0,0 +1,53 @@
+import unittest
+import numpy as np
+
+from chroma.geometry import Solid, Geometry
+from chroma.make import box
+from chroma.sim import Simulation
+from chroma.optics import vacuum
+from chroma.event import Photons
+
+class TestPropagation(unittest.TestCase):
+    def testAbort(self):
+        '''Photons that hit a triangle at normal incidence should not abort.
+
+        Photons that hit a triangle at exactly normal incidence can sometimes produce a dot product
+        that is outside the range allowed by acos().  Trigger these with axis aligned photons in a box
+        '''
+
+        # Setup geometry
+        cube = Geometry()
+        cube.add_solid(Solid(box(100,100,100), vacuum, vacuum))
+        cube.pmtids = [0]
+        sim = Simulation(cube, vacuum, bvh_bits=4, geant4_processes=0,
+                              use_cache=False)
+
+        # Create initial photons
+        nphotons = 10000
+        positions = np.tile([0,0,0], (nphotons,1)).astype(np.float32)
+        directions = np.tile([0,0,1], (nphotons,1)).astype(np.float32)
+        polarizations = np.zeros_like(positions)
+        phi = np.random.uniform(0, 2*np.pi, nphotons).astype(np.float32)
+        polarizations[:,0] = np.cos(phi)
+        polarizations[:,1] = np.sin(phi)
+        times = np.zeros(nphotons, dtype=np.float32)
+        wavelengths = np.empty(nphotons, np.float32)
+        wavelengths.fill(400.0)
+
+        photons = Photons(positions=positions, directions=directions, polarizations=polarizations,
+                          times=times, wavelengths=wavelengths)
+
+        # First make one step to check for strangeness
+        photon_stop = sim.propagate_photons(photons, max_steps=1)
+        self.assertFalse(np.isnan(photon_stop.positions).any())
+        self.assertFalse(np.isnan(photon_stop.directions).any())
+        self.assertFalse(np.isnan(photon_stop.polarizations).any())
+        self.assertFalse(np.isnan(photon_stop.times).any())
+        self.assertFalse(np.isnan(photon_stop.wavelengths).any())
+
+        # Now let it run the usual ten steps
+        photon_stop = sim.propagate_photons(photons, max_steps=10)
+        aborted = (photon_stop.histories & (1 << 31)) > 0
+        print 'aborted photons: %1.1f' % (float(np.count_nonzero(aborted)) / nphotons)
+        self.assertFalse(aborted.any())
+