Fix space regen Z placement for centered representations

get_x_y_z_h_mat_from_obj computes z from bound_box[0], which differs from obj.location.z when the representation is centered at origin (e.g., a PolygonalFaceSet unit cube). The previous fix (24f7629f) removed translate_obj_to_z_location to prevent doubling Z for extrusion representations, but that broke centered ones where z != location.z.

Replace the removed relative translate with an absolute active_obj.location.z = z. This is a no-op for extrusion representations (z == location.z) and corrects the position for centered ones.

Add test_regenerate_space_from_centered_cube_representation to cover the regeneration path with a centered mesh representation.

Generated with the assistance of an AI coding tool.

src/bonsai/bonsai/core/spatial.py

@@ -229,6 +229,8 @@ def generate_space(
             h = auto_h
 
     if element and element.is_a("IfcSpace"):
+        assert active_obj
+        active_obj.location.z = z
         spatial.set_space_representation_from_polygon(active_obj, element, space_polygon, h, polygon_is_si=True)
     else:
         if relating_type:

src/bonsai/test/tool/test_spatial.py

@@ -426,3 +426,63 @@ class TestGenerateSpace(NewFile):
         bpy.ops.bim.generate_space()
         new_height = space.dimensions.z
         assert new_height != original_height or new_height > 0
+
+    def test_regenerate_space_from_centered_cube_representation(self):
+        bpy.ops.bim.create_project()
+        ifc = tool.Ifc.get()
+        _BlockHelper.create_wall(ifc, height=10.0)
+        scene = bpy.context.scene
+        scene.cursor.location = (0, 0, 0)
+
+        # Create a space with a unit cube PolygonalFaceSet centered at local origin.
+        ctx = ifcopenshell.util.representation.get_context(ifc, "Model", "Body", "MODEL_VIEW")
+        points = ifc.createIfcCartesianPointList3D(
+            [
+                (-0.5, -0.5, -0.5),
+                (-0.5, -0.5, 0.5),
+                (-0.5, 0.5, -0.5),
+                (-0.5, 0.5, 0.5),
+                (0.5, -0.5, -0.5),
+                (0.5, -0.5, 0.5),
+                (0.5, 0.5, -0.5),
+                (0.5, 0.5, 0.5),
+            ]
+        )
+        faces = [
+            ifc.createIfcIndexedPolygonalFace([1, 2, 4, 3]),
+            ifc.createIfcIndexedPolygonalFace([3, 4, 8, 7]),
+            ifc.createIfcIndexedPolygonalFace([7, 8, 6, 5]),
+            ifc.createIfcIndexedPolygonalFace([5, 6, 2, 1]),
+            ifc.createIfcIndexedPolygonalFace([3, 7, 5, 1]),
+            ifc.createIfcIndexedPolygonalFace([8, 4, 2, 6]),
+        ]
+        face_set = ifc.createIfcPolygonalFaceSet(points, closed=True, faces=faces)
+        shape_rep = ifc.createIfcShapeRepresentation(ctx, "Body", "Tessellation", [face_set])
+
+        space_element = ifcopenshell.api.root.create_entity(ifc, ifc_class="IfcSpace")
+        space_element.Representation = ifc.createIfcProductDefinitionShape(None, None, [shape_rep])
+
+        bpy.ops.mesh.primitive_cube_add(size=1, location=(0, 0, 5))
+        obj = bpy.data.objects["Cube"]
+        scene.collection.objects.link(obj)
+        tool.Ifc.link(space_element, obj)
+        bpy.context.view_layer.update()
+        obj.name = "MySpace"
+
+        # Check the cube's world bottom Z before regeneration.
+        bottom_z = (obj.matrix_world @ Vector(obj.bound_box[0])).z
+        assert np.isclose(bottom_z, 4.5), f"Expected bottom_z=4.5, got {bottom_z}"
+
+        # Regenerate the space.
+        bpy.context.view_layer.objects.active = obj
+        obj.select_set(True)
+        bpy.ops.bim.generate_space()
+
+        mesh = obj.data
+        assert isinstance(mesh, bpy.types.Mesh)
+        verts = [v.co.z for v in mesh.vertices]
+        min_z = min(verts)
+        max_z = max(verts)
+        assert min_z >= 0, f"Expected extrusion to start at local z>=0, got min_z={min_z}"
+        assert max_z > 0, f"Expected extrusion to have positive height, got max_z={max_z}"
+        assert np.isclose(obj.location.z, 4.5, atol=0.01), f"Expected location.z=4.5, got {obj.location.z}"