bim.generate_space not to fail silently

src/bonsai/bonsai/bim/module/model/space.py

@@ -42,8 +42,8 @@ class GenerateSpace(bpy.types.Operator, tool.Ifc.Operator):
 
         try:
             core.generate_space(tool.Ifc, tool.Model, tool.Root, tool.Spatial, tool.Type)
-        except core.NoDefaultContainer:
+        except core.SpaceGenerationError as e:
-            return self.report({"ERROR"}, "Please set a default container to create the space in.")
+            return self.report({"ERROR"}, str(e))
 
 
 class GenerateSpacesFromWalls(bpy.types.Operator, tool.Ifc.Operator):

src/bonsai/bonsai/bim/module/spatial/workspace.py

@@ -156,8 +156,8 @@ class Hotkey(bpy.types.Operator, tool.Ifc.Operator):
         else:
             try:
                 bonsai.core.spatial.generate_space(tool.Ifc, tool.Model, tool.Root, tool.Spatial, tool.Type)
-            except bonsai.core.spatial.NoDefaultContainer:
+            except bonsai.core.spatial.SpaceGenerationError as e:
-                return self.report({"ERROR"}, "Please set a default container to create the space in.")
+                return self.report({"ERROR"}, str(e))
 
     def hotkey_S_B(self):
         bpy.ops.bim.add_boundary()

src/bonsai/bonsai/core/covering.py

@@ -46,7 +46,7 @@ def add_instance_flooring_covering_from_cursor(ifc: tool.Ifc, root: tool.Root, s
 
     space_polygon = spatial.get_space_polygon_from_context_visible_objects(x, y)
 
-    if not space_polygon:
+    if isinstance(space_polygon, str):
         return
 
     bm = spatial.get_bmesh_from_polygon(space_polygon, h=0)
@@ -91,7 +91,7 @@ def add_instance_ceiling_covering_from_cursor(
 
     space_polygon = spatial.get_space_polygon_from_context_visible_objects(x, y)
 
-    if not space_polygon:
+    if isinstance(space_polygon, str):
         return
 
     bm = spatial.get_bmesh_from_polygon(space_polygon, h=0)
@@ -123,7 +123,7 @@ def regen_selected_covering_object(root: tool.Root, spatial: tool.Spatial) -> No
 
     space_polygon = spatial.get_space_polygon_from_context_visible_objects(x, y)
 
-    if not space_polygon:
+    if isinstance(space_polygon, str):
         return
 
     bm = spatial.get_bmesh_from_polygon(space_polygon, h=0)

src/bonsai/bonsai/core/spatial.py

@@ -17,7 +17,7 @@
 # along with Bonsai.  If not, see <http://www.gnu.org/licenses/>.
 
 from __future__ import annotations
-from typing import TYPE_CHECKING, Optional, Union
+from typing import TYPE_CHECKING, Optional, Union, assert_never
 
 if TYPE_CHECKING:
     import bpy
@@ -152,9 +152,14 @@ def select_decomposed_element(ifc: tool.Ifc, spatial: tool.Spatial, element: ifc
     spatial.set_active_object(ifc.get_object(element))
 
 
-def generate_space(ifc: tool.Ifc, model: tool.Model, root: tool.Root, spatial: tool.Spatial, type: tool.Type) -> None:
+def generate_space(
+    ifc: tool.Ifc, model: tool.Model, root: tool.Root, spatial: tool.Spatial, type: tool.Type
+) -> Union[None, str]:
+    """
+    :return: None if successful, error message string if not.
+    """
     if not root.get_default_container():
-        raise NoDefaultContainer()
+        raise SpaceGenerationError("Please set a default container to create the space in.")
 
     active_obj = spatial.get_active_obj()
     selected_objects = spatial.get_selected_objects()
@@ -175,8 +180,17 @@ def generate_space(ifc: tool.Ifc, model: tool.Model, root: tool.Root, spatial: t
 
     space_polygon = spatial.get_space_polygon_from_context_visible_objects(x, y)
 
-    if not space_polygon:
+    if isinstance(space_polygon, str):
-        return
+        if space_polygon == "NO POLYGONS FOUND":
+            raise SpaceGenerationError(
+                "Couldn't find any polygons to form the space shape. Perhaps, RL value need to be adjusted."
+            )
+        elif space_polygon == "NO POLYGON FOR POINT":
+            raise SpaceGenerationError(
+                f"Couldn't find any polygons containing the position ({x}, {y}). Perhaps, RL value need to be adjusted."
+            )
+        else:
+            assert space_polygon
 
     bm = spatial.get_bmesh_from_polygon(space_polygon, h=h, polygon_is_si=True)
 
@@ -244,5 +258,5 @@ def set_default_container(spatial: tool.Spatial, container: ifcopenshell.entity_
     spatial.set_default_container(container)
 
 
-class NoDefaultContainer(Exception):
+class SpaceGenerationError(Exception):
     pass

src/bonsai/bonsai/tool/spatial.py

@@ -628,14 +628,20 @@ class Spatial(bonsai.core.tool.Spatial):
         return False
 
     @classmethod
-    def get_space_polygon_from_context_visible_objects(cls, x: float, y: float) -> Union[shapely.Polygon, None]:
+    def get_space_polygon_from_context_visible_objects(
+        cls, x: float, y: float
+    ) -> Union[shapely.Polygon, Literal["NO POLYGONS FOUND", "NO POLYGON FOR POINT"]]:
         boundary_lines = cls.get_boundary_lines_from_context_visible_objects()
         unioned_boundaries = shapely.union_all(shapely.GeometryCollection(boundary_lines))
         closed_polygons = shapely.polygonize(unioned_boundaries.geoms)
+        if not closed_polygons:
+            return "NO POLYGONS FOUND"
         space_polygon = None
         for polygon in closed_polygons.geoms:
             if shapely.contains_xy(polygon, x, y):
                 space_polygon = shapely.force_3d(polygon)
+        if space_polygon is None:
+            return "NO POLYGON FOR POINT"
         return space_polygon
 
     @classmethod