WIP you can now partially edit the object placement of an object. See #1222.

src/ifcblenderexport/blenderbim/bim/module/geometry/add_object_placement.py

@@ -0,0 +1,63 @@
+import numpy as np
+import ifcopenshell.util.placement
+
+
+class Usecase:
+    def __init__(self, file, settings=None):
+        self.file = file
+        self.settings = {
+            "product": None,
+            "matrix": np.eye(4)
+        }
+        for key, value in settings.items():
+            self.settings[key] = value
+
+    def execute(self):
+        self.unit_scale = ifcopenshell.util.unit.calculate_unit_scale(self.file)
+        if not self.settings["product"].ObjectPlacement:
+            placement_rel_to = None
+        else:
+            placement_rel_to = self.settings["product"].ObjectPlacement.PlacementRelTo
+        placement = self.file.createIfcLocalPlacement(
+            placement_rel_to, self.get_relative_placement(placement_rel_to)
+        )
+        self.settings["product"].ObjectPlacement = placement
+        return placement
+
+    def get_relative_placement(self, placement_rel_to):
+        if placement_rel_to:
+            relating_object_matrix = ifcopenshell.util.placement.get_local_placement(placement_rel_to)
+            relating_object_matrix[0][3] = self.convert_unit_to_si(relating_object_matrix[0][3])
+            relating_object_matrix[1][3] = self.convert_unit_to_si(relating_object_matrix[1][3])
+            relating_object_matrix[2][3] = self.convert_unit_to_si(relating_object_matrix[2][3])
+        else:
+            relating_object_matrix = np.eye(4)
+        m = self.settings["matrix"]
+        x = np.array((m[0][0], m[1][0], m[2][0]))
+        z = np.array((m[0][2], m[1][2], m[2][2]))
+        o = np.array((m[0][3], m[1][3], m[2][3]))
+        object_matrix = ifcopenshell.util.placement.a2p(o, z, x)
+        #relative_placement_matrix = relating_object_matrix.inverted() @ object_matrix
+        relative_placement_matrix = relating_object_matrix @ object_matrix
+        return self.create_ifc_axis_2_placement_3d(
+            relative_placement_matrix[:,3][0:3],
+            relative_placement_matrix[:,2][0:3],
+            relative_placement_matrix[:,0][0:3],
+        )
+
+    def create_ifc_axis_2_placement_3d(self, point, up, forward):
+        return self.file.createIfcAxis2Placement3D(
+            self.create_cartesian_point(point),
+            self.file.createIfcDirection(up.tolist()),
+            self.file.createIfcDirection(forward.tolist()),
+        )
+
+    def create_cartesian_point(self, co):
+        co = self.convert_si_to_unit(co)
+        return self.file.createIfcCartesianPoint(co.tolist())
+
+    def convert_si_to_unit(self, co):
+        return co / self.unit_scale
+
+    def convert_unit_to_si(self, co):
+        return co * self.unit_scale

src/ifcblenderexport/blenderbim/bim/module/geometry/add_shape_representation.py

@@ -21,26 +21,13 @@ class Usecase:
 
     def execute(self):
         if self.settings["unit_scale"] is None:
-            self.settings["unit_scale"] = self.calculate_unit_scale()
+            self.settings["unit_scale"] = ifcopenshell.util.unit.calculate_unit_scale(self.file)
         if self.settings["context"].ContextType == "Model":
             return self.create_model_representation()
         elif self.settings["context"].ContextType == "Plan":
             return self.create_plan_representation()
         return self.create_variable_representation()
 
-    def calculate_unit_scale(self):
-        units = self.file.by_type("IfcUnitAssignment")[0]
-        unit_scale = 1
-        for unit in units.Units:
-            if not hasattr(unit, "UnitType") or unit.UnitType != "LENGTHUNIT":
-                continue
-            while unit.is_a("IfcConversionBasedUnit"):
-                unit_scale *= unit.ConversionFactor.ValueComponent.wrappedValue
-                unit = unit.ConversionFactor.UnitComponent
-            if unit.is_a("IfcSIUnit"):
-                unit_scale *= ifcopenshell.util.unit.get_prefix_multiplier(unit.Prefix)
-        return unit_scale
-
     def create_model_representation(self):
         if self.settings["context"].is_a() == "IfcGeometricRepresentationContext":
             return self.create_variable_representation()

src/ifcblenderexport/blenderbim/bim/operator.py

@@ -13,6 +13,7 @@ import ifcopenshell.util.geolocation
 import ifcopenshell.util.element
 import ifcopenshell.util.schema
 import tempfile
+import numpy as np
 from . import export_ifc
 from . import import_ifc
 from . import qto
@@ -4351,6 +4352,13 @@ class BakeParametricGeometry(bpy.types.Operator):
         self.file = ifc.IfcStore.get_file()
         element = self.file.by_id(obj.data.BIMMeshProperties.ifc_definition_id)
 
+        import blenderbim.bim.module.geometry.add_object_placement as add_object_placement
+        usecase = add_object_placement.Usecase(self.file, {
+            "product": self.file.by_id(obj.BIMObjectProperties.ifc_definition_id),
+            "matrix": np.array(obj.matrix_world)
+        })
+        result = usecase.execute()
+
         import blenderbim.bim.module.geometry.add_shape_representation as add_shape_representation
         usecase = add_shape_representation.Usecase(self.file, {
             "context": element.ContextOfItems,

src/ifcopenshell-python/ifcopenshell/util/unit.py

@@ -142,3 +142,17 @@ def convert(value, from_prefix, from_unit, to_prefix, to_unit):
             value *= 1 / get_prefix_multiplier(to_prefix)
             value *= 1 / get_prefix_multiplier(to_prefix)
     return value
+
+
+def calculate_unit_scale(file):
+    units = file.by_type("IfcUnitAssignment")[0]
+    unit_scale = 1
+    for unit in units.Units:
+        if not hasattr(unit, "UnitType") or unit.UnitType != "LENGTHUNIT":
+            continue
+        while unit.is_a("IfcConversionBasedUnit"):
+            unit_scale *= unit.ConversionFactor.ValueComponent.wrappedValue
+            unit = unit.ConversionFactor.UnitComponent
+        if unit.is_a("IfcSIUnit"):
+            unit_scale *= get_prefix_multiplier(unit.Prefix)
+    return unit_scale