Make LinePosition camera-relative in section/elevation views

_get_line_offset_direction now uses cross(camera_dir, dim_dir) instead of
cross(world_Z, dim_dir) when the camera is mostly horizontal (section or
elevation view).  This keeps the offset axis in the view plane so the
DimensionLinePositionWidget gizmo drags the line visually up/down rather
than in/out of the screen.

Plan view behaviour (cross(world_Z, dim_dir)) is preserved unchanged so
existing stored LinePosition values continue to work.

camera_dir is threaded through regenerate_dimension(), _get_line_offset_direction(),
and all callers: gizmos.py (_set_pos / _offset_dir), prop.py (_get/_set_line_position),
handler.py (regenerate_dims_for_layer and depsgraph handler), and all three
operator.py call sites (DrawParametricDimension, _do_write_anchor,
RegenerateDimensions).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/bonsai/bonsai/bim/module/drawing/gizmos.py

@@ -2818,8 +2818,23 @@ class DimensionLinePositionWidget(types.GizmoGroup):
     # Helpers
 
     @staticmethod
-    def _offset_dir(obj: bpy.types.Object) -> "Vector | None":
+    def _cam_dir() -> "Vector | None":
-        """World-space unit direction perpendicular to the dimension line and world_Z."""
+        """Scene camera forward direction, or None."""
+        cam = bpy.context.scene.camera
+        if not cam:
+            return None
+        return (cam.matrix_world.to_3x3() @ Vector((0.0, 0.0, -1.0))).normalized()
+
+    @classmethod
+    def _offset_dir(cls, obj: bpy.types.Object) -> "Vector | None":
+        """World-space direction perpendicular to the dimension line and in the view plane.
+
+        Plan view  (camera mostly vertical): cross(world_Z, dim_dir) — preserves
+        existing stored LinePosition values.
+        Section/elevation (camera mostly horizontal): cross(cam_forward, dim_dir) —
+        keeps the offset axis inside the view plane so the gizmo moves the line
+        visually sideways (up/down in section) rather than into/out of the screen.
+        """
         if not obj.data or not hasattr(obj.data, "splines") or not obj.data.splines:
             return None
         spline = obj.data.splines[0]
@@ -2831,8 +2846,10 @@ class DimensionLinePositionWidget(types.GizmoGroup):
         if dim.length < 1e-10:
             return None
         dim.normalize()
-        world_z = Vector((0.0, 0.0, 1.0))
+        cam_view = cls._cam_dir()
-        od = world_z.cross(dim)
+        cam_is_plan = (cam_view is None) or abs(cam_view.z) > 0.7
+        ref = Vector((0.0, 0.0, 1.0)) if cam_is_plan else cam_view
+        od = ref.cross(dim)
         if od.length < 1e-6:
             od = Vector((1.0, 0.0, 0.0)).cross(dim)
         if od.length < 1e-6:
@@ -2920,7 +2937,11 @@ class DimensionLinePositionWidget(types.GizmoGroup):
             except Exception:
                 pass
 
-        resolved_pts = drawing_api.regenerate_dimension(file, element, placement_override=placement_override)
+        cam_view = self._cam_dir()
+        cam_dir_tuple = tuple(cam_view) if cam_view is not None else None
+        resolved_pts = drawing_api.regenerate_dimension(
+            file, element, placement_override=placement_override, camera_dir=cam_dir_tuple
+        )
         if resolved_pts:
             _update_blender_curve(element, resolved_pts)
         tool.Blender.update_viewport()

src/bonsai/bonsai/bim/module/drawing/handler.py

@@ -113,6 +113,12 @@ def regenerate_dims_for_layer(file, layer) -> None:
     geom_settings = ifcopenshell.geom.settings()
     geom_settings.set("APPLY_DEFAULT_MATERIALS", False)
 
+    cam = bpy.context.scene.camera
+    cam_dir_tuple = None
+    if cam:
+        from mathutils import Vector as _Vec
+        cam_dir_tuple = tuple((cam.matrix_world.to_3x3() @ _Vec((0, 0, -1))).normalized())
+
     for ann_id in annotation_ids:
         try:
             annotation = file.by_id(ann_id)
@@ -143,6 +149,7 @@ def regenerate_dims_for_layer(file, layer) -> None:
             settings=geom_settings,
             shape_cache=_dim_shape_cache,
             placement_override=placement_override,
+            camera_dir=cam_dir_tuple,
         )
         if resolved_pts:
             _update_blender_curve(annotation, resolved_pts)

src/bonsai/bonsai/bim/module/drawing/operator.py

@@ -6397,10 +6397,15 @@ class DrawParametricDimension(bpy.types.Operator, PolylineOperator, tool.Ifc.Ope
                     placement_override[elem.id()] = np.array(elem_obj.matrix_world)
             except Exception:
                 pass
+        _cam = bpy.context.scene.camera
+        _cam_dir_tuple = None
+        if _cam:
+            _cam_dir_tuple = tuple((bpy.context.scene.camera.matrix_world.to_3x3() @ Vector((0, 0, -1))).normalized())
         resolved_pts = drawing_api.regenerate_dimension(
             file, annotation,
             shape_cache=getattr(self, "_shape_cache", None),
             placement_override=placement_override,
+            camera_dir=_cam_dir_tuple,
         )
         if resolved_pts:
             _update_blender_curve(annotation, resolved_pts)
@@ -7669,12 +7674,18 @@ def _do_write_anchor(annotation, annotation_obj, new_anchor: dict, vertex_index:
     if _is_elevation:
         _update_elevation_marker_z(file, annotation, shape_cache=shape_cache, placement_override=placement_override)
     else:
+        import bpy as _bpy
         import ifcopenshell.api.drawing as drawing_api
+        _cam = _bpy.context.scene.camera
+        _cam_dir_tuple = None
+        if _cam:
+            _cam_dir_tuple = tuple((_cam.matrix_world.to_3x3() @ Vector((0, 0, -1))).normalized())
         resolved_pts = drawing_api.regenerate_dimension(
             file,
             annotation,
             shape_cache=shape_cache,
             placement_override=placement_override,
+            camera_dir=_cam_dir_tuple,
         )
         if resolved_pts:
             _update_blender_curve(annotation, resolved_pts)
@@ -7944,6 +7955,11 @@ class RegenerateDimensions(bpy.types.Operator, tool.Ifc.Operator):
 
         from bonsai.bim.module.drawing.handler import _sync_dimension_anchors_to_curve
 
+        _cam = context.scene.camera
+        _cam_dir_tuple = None
+        if _cam:
+            _cam_dir_tuple = tuple((_cam.matrix_world.to_3x3() @ Vector((0, 0, -1))).normalized())
+
         updated = 0
         for annotation in candidates:
             pset = ifcopenshell.util.element.get_pset(annotation, "BBIM_Dimension")
@@ -7998,6 +8014,7 @@ class RegenerateDimensions(bpy.types.Operator, tool.Ifc.Operator):
                     settings=geom_settings,
                     shape_cache=shape_cache,
                     placement_override=placement_override,
+                    camera_dir=_cam_dir_tuple,
                 )
                 if not resolved_pts:
                     continue

src/bonsai/bonsai/bim/module/drawing/prop.py

@@ -1135,13 +1135,27 @@ def _get_line_position(self) -> float:
                             m = math.sqrt(dx * dx + dy * dy + dz * dz)
                             if m > 1e-10:
                                 ddx, ddy, ddz = dx / m, dy / m, dz / m
-                                # cross(world_Z=(0,0,1), dim_dir) = (-ddy, ddx, 0)
+                                cam = _bpy.context.scene.camera
-                                ox, oy, oz = -ddy, ddx, 0.0
+                                cam_is_plan = True
-                                om = math.sqrt(ox * ox + oy * oy)
+                                cvx, cvy, cvz = 0.0, 0.0, 1.0
+                                if cam:
+                                    from mathutils import Vector as _Vec
+                                    cv = (cam.matrix_world.to_3x3() @ _Vec((0, 0, -1))).normalized()
+                                    cvx, cvy, cvz = cv.x, cv.y, cv.z
+                                    cam_is_plan = abs(cvz) > 0.7
+                                if cam_is_plan:
+                                    # cross(world_Z, dim_dir)
+                                    ox, oy, oz = -ddy, ddx, 0.0
+                                else:
+                                    # cross(cam_dir, dim_dir)
+                                    ox = cvy * ddz - cvz * ddy
+                                    oy = cvz * ddx - cvx * ddz
+                                    oz = cvx * ddy - cvy * ddx
+                                om = math.sqrt(ox * ox + oy * oy + oz * oz)
                                 if om > 1e-6:
-                                    od = (ox / om, oy / om, 0.0)
+                                    od = (ox / om, oy / om, oz / om)
                                     pt = anchors[0]["pt"]
-                                    return float(pt[0] * od[0] + pt[1] * od[1])
+                                    return float(pt[0] * od[0] + pt[1] * od[1] + pt[2] * od[2])
     except Exception:
         pass
     return 0.0
@@ -1180,6 +1194,12 @@ def _set_line_position(self, value: float) -> None:
 
     from bonsai.bim.module.drawing.operator import _update_blender_curve
 
+    cam = _bpy.context.scene.camera
+    cam_dir_tuple = None
+    if cam:
+        from mathutils import Vector as _Vec
+        cam_dir_tuple = tuple((cam.matrix_world.to_3x3() @ _Vec((0, 0, -1))).normalized())
+
     for obj, element, pset_data in targets:
         pset_entity = file.by_id(pset_data["id"])
         ifcopenshell.api.pset.edit_pset(file, pset=pset_entity, properties={"LinePosition": value})
@@ -1198,7 +1218,9 @@ def _set_line_position(self, value: float) -> None:
             except Exception:
                 pass
 
-        resolved_pts = drawing_api.regenerate_dimension(file, element, placement_override=placement_override)
+        resolved_pts = drawing_api.regenerate_dimension(
+            file, element, placement_override=placement_override, camera_dir=cam_dir_tuple
+        )
         if resolved_pts:
             _update_blender_curve(element, resolved_pts)