Dumb slabs now roundtrip the Blender solidify modifier

src/blenderbim/blenderbim/bim/ifc.py

@@ -14,6 +14,7 @@ class IfcStore:
     pset_template_file = None
     library_path = ""
     library_file = None
+    element_listeners = set()
 
     @staticmethod
     def purge():
@@ -60,6 +61,10 @@ class IfcStore:
             return
         return obj
 
+    @staticmethod
+    def add_element_listener(callback):
+        IfcStore.element_listeners.add(callback)
+
     @staticmethod
     def link_element(element, obj):
         IfcStore.id_map[element.id()] = obj
@@ -68,6 +73,8 @@ class IfcStore:
         obj.BIMObjectProperties.ifc_definition_id = element.id()
         blenderbim.bim.handler.subscribe_to(obj, "mode", blenderbim.bim.handler.mode_callback)
         blenderbim.bim.handler.subscribe_to(obj, "name", blenderbim.bim.handler.name_callback)
+        for listener in IfcStore.element_listeners:
+            listener(element, obj)
 
     @staticmethod
     def unlink_element(element=None, obj=None):

src/blenderbim/blenderbim/bim/module/model/handler.py

@@ -2,15 +2,19 @@ import bpy
 import ifcopenshell
 import ifcopenshell.api
 from blenderbim.bim.module.model import product, wall, slab
+from blenderbim.bim.ifc import IfcStore
 from bpy.app.handlers import persistent
 
 
 @persistent
 def load_post(*args):
     ifcopenshell.api.add_post_listener("geometry.add_representation", None, product.generate_box)
+
     ifcopenshell.api.add_post_listener("geometry.add_representation", None, wall.generate_axis)
     ifcopenshell.api.add_post_listener("geometry.add_representation", None, wall.calculate_quantities)
     ifcopenshell.api.add_pre_listener("material.edit_layer", None, wall.DumbWallPlaner().regenerate_from_layer)
     ifcopenshell.api.add_pre_listener("type.assign_type", None, wall.DumbWallPlaner().regenerate_from_type)
+
+    IfcStore.add_element_listener(slab.element_listener)
     ifcopenshell.api.add_pre_listener("material.edit_layer", None, slab.DumbSlabPlaner().regenerate_from_layer)
     ifcopenshell.api.add_pre_listener("type.assign_type", None, slab.DumbSlabPlaner().regenerate_from_type)

src/blenderbim/blenderbim/bim/module/model/slab.py

@@ -5,12 +5,53 @@ import ifcopenshell
 import ifcopenshell.util.type
 import ifcopenshell.util.unit
 import mathutils.geometry
+import blenderbim.bim.handler
 from blenderbim.bim.ifc import IfcStore
 from math import pi, degrees
 from mathutils import Vector, Matrix
 from ifcopenshell.api.material.data import Data as MaterialData
 
 
+def element_listener(element, obj):
+    blenderbim.bim.handler.subscribe_to(obj, "mode", mode_callback)
+
+
+def mode_callback(obj, data):
+    for obj in bpy.context.selected_objects + [bpy.context.active_object]:
+        if (
+            obj.mode != "EDIT"
+            or not obj.data
+            or not isinstance(obj.data, (bpy.types.Mesh, bpy.types.Curve, bpy.types.TextCurve))
+            or not obj.BIMObjectProperties.ifc_definition_id
+            or not bpy.context.scene.BIMProjectProperties.is_authoring
+        ):
+            return
+        product = IfcStore.get_file().by_id(obj.BIMObjectProperties.ifc_definition_id)
+        parametric = ifcopenshell.util.element.get_psets(product).get("EPset_Parametric")
+        if parametric and parametric["Engine"] != "BlenderBIM.DumbSlab":
+            return
+        modifier = [m for m in obj.modifiers if m.type == "SOLIDIFY"]
+        if modifier:
+            return
+        depth = obj.dimensions.z
+        bm = bmesh.from_edit_mesh(obj.data)
+        bmesh.ops.dissolve_limit(bm, angle_limit=pi / 180 * 1, verts=bm.verts, edges=bm.edges)
+        bm.faces.ensure_lookup_table()
+        non_bottom_faces = []
+        for face in bm.faces:
+            if face.normal.z > -0.9:
+                non_bottom_faces.append(face)
+            else:
+                face.normal_flip()
+        bmesh.ops.delete(bm, geom=non_bottom_faces, context="FACES")
+        bmesh.update_edit_mesh(obj.data)
+        bm.free()
+        modifier = obj.modifiers.new("Slab Depth", "SOLIDIFY")
+        modifier.use_even_offset = True
+        modifier.offset = 1
+        modifier.thickness = depth
+
+
 class DumbSlabGenerator:
     def __init__(self, relating_type):
         self.relating_type = relating_type

src/blenderbim/blenderbim/bim/module/model/wall.py

@@ -686,7 +686,6 @@ class DumbWallGenerator:
         return obj
 
 
-
 def generate_axis(usecase_path, ifc_file, **settings):
     axis_context = ifcopenshell.util.representation.get_context(ifc_file, "Model", "Axis", "GRAPH_VIEW")
     if not axis_context:
@@ -747,13 +746,19 @@ def calculate_quantities(usecase_path, ifc_file, **settings):
         net_volume = gross_volume
         bm.free()
 
-    ifcopenshell.api.run("pset.edit_qto", ifc_file, should_run_listeners=False, qto=qto, properties={
-        "Length": round(length, 2),
-        "Width": round(width, 2),
-        "Height": round(height, 2),
-        "GrossVolume": round(gross_volume, 2),
-        "NetVolume": round(net_volume, 2)
-    })
+    ifcopenshell.api.run(
+        "pset.edit_qto",
+        ifc_file,
+        should_run_listeners=False,
+        qto=qto,
+        properties={
+            "Length": round(length, 2),
+            "Width": round(width, 2),
+            "Height": round(height, 2),
+            "GrossVolume": round(gross_volume, 2),
+            "NetVolume": round(net_volume, 2),
+        },
+    )
     PsetData.load(ifc_file, obj.BIMObjectProperties.ifc_definition_id)
 
 
@@ -835,7 +840,7 @@ class DumbWallPlaner:
                 break
             if not slide_vector:
                 continue
-            slide_vector *= (slide_magnitude / abs(slide_vector.y))
+            slide_vector *= slide_magnitude / abs(slide_vector.y)
             vert.co += slide_vector
 
     # An end face is a quad that is on one end of the wall or the other. It must