Invert rotation axis for negative scans (#694)

This complements 39e463e. Twirling, always twirling.
cctbx · Feb 13, 2024 · f901366 · f901366
1 parent 39e463e
commit f901366
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Showing 2 changed files with 8 additions and 2 deletions.
diff --git a/newsfragments/694.misc b/newsfragments/694.misc
@@ -0,0 +1 @@
+NXmx: if reversed, reverse rotation axis. This is part 2 of previous commit.
diff --git a/src/dxtbx/format/FormatNXmx.py b/src/dxtbx/format/FormatNXmx.py
@@ -99,11 +99,16 @@ def _start(self):
             scan = self._scan_model
             oscillation = scan.get_oscillation()
 
-            # FIXME this really should not be correct but it works in this one
-            # weird case
             if oscillation[1] < 0:
+                # invert the scan parameters so that the attitude of roation is positive
                 self._scan_model.set_oscillation((-oscillation[0], -oscillation[1]))
 
+                # invert the axis direction so that the universe is aligned
+                axes = self._goniometer_model.get_axes()
+                axis = self._goniometer_model.get_scan_axis()
+                axes[axis] = -1 * axes[axis][0], -1 * axes[axis][1], -1 * axes[axis][2]
+                self._goniometer_model.set_axes(axes)
+
     def _get_nxmx(self, fh: h5py.File):
         return nxmx.NXmx(fh)