Fix off-axis rendering when center is not [0.5, 0.5, 0.5]

yt/visualization/plot_window.py

@@ -26,6 +26,7 @@
     validate_moment,
 )
 from yt.geometry.api import Geometry
+from yt.geometry.oct_geometry_handler import OctreeIndex
 from yt.units.unit_object import Unit  # type: ignore
 from yt.units.unit_registry import UnitParseError  # type: ignore
 from yt.units.yt_array import YTArray, YTQuantity
@@ -2494,7 +2495,12 @@ def __init__(
         is_sph_field = finfo.is_sph_field
         particle_datasets = (ParticleDataset, StreamParticlesDataset)
 
-        if isinstance(data_source.ds, particle_datasets) and is_sph_field:
+        dom_width = data_source.ds.domain_width
+        cubic_domain = dom_width.max() == dom_width.min()
+
+        if (isinstance(data_source.ds, particle_datasets) and is_sph_field) or (
+            isinstance(data_source.ds.index, OctreeIndex) and cubic_domain
+        ):
             center_use = parse_center_array(center, ds=data_source.ds, axis=None)
         else:
             center_use = center_rot

yt/visualization/volume_rendering/off_axis_projection.py

@@ -444,21 +444,22 @@ def temp_weightfield(field, data):
         # We need the width of the plot window in projected coordinates,
         # i.e. we ignore the z-component
         wmax = width[:2].max()
-
-        # Normalize the positions & dx so that they are in the range [-0.5, 0.5]
+        # Recenter positions w.r.t. center of the plot window
         xyz = np.stack(
-            [
-                ((data_source["index", k] - center[i]) / wmax).to("1").d
-                for i, k in enumerate("xyz")
-            ],
-            axis=-1,
+            [data_source["index", k] - center[i] for i, k in enumerate("xyz")], axis=-1
         )
 
+        # If we have periodic boundaries, we need to wrap the positions
         for idim, periodic in enumerate(data_source.ds.periodicity):
             if not periodic:
                 continue
-            # Wrap into [-0.5, +0.5]
-            xyz[..., idim] = (xyz[..., idim] + 0.5) % 1 - 0.5
+            w = data_source.ds.domain_width[idim]
+            # Wrap into [-w/2, +w/2]
+            xyz[..., idim] = (xyz[..., idim] + w / 2) % w - w / 2
+
+        # Rescale to [-0.5, +0.5]
+        xyz /= wmax
+        xyz = xyz.to("1").d
 
         dx = (data_source["index", "dx"] / wmax).to("1").d