Add footprint corner sampling for roof detection

get_vertical_bounding_planes now also casts rays from the footprint
polygon's corner vertices, offset slightly inward toward the centroid.
This catches bounding elements (e.g. sloped roofs) that only cover a
corner of the space.

Generated with the assistance of an AI coding tool.

src/bonsai/test/tool/test_spatial.py

@@ -685,10 +685,16 @@ class TestRegenerateSpaceFromRealIfc2x3(NewFile):
         ifc = self.load_house_with_garage()
         (original_bounds, original_origin), (regen_bounds, regen_origin) = self._regenerate_space(ifc, 2363)
         assert (regen_origin - original_origin).length < 0.02
-        # X, Y, Z-min stable; Z-max may differ because the regenerated space
+        # X and Y stable; Z may differ because the regenerated space detects the
-        # correctly detects the roof and clips to a different top elevation.
+        # sloped roof and clips the extrusion.
-        for j in (0, 1, 4):
+        for j in (0, 1, 2, 3, 4):
             assert regen_bounds[j] == pytest.approx(original_bounds[j], abs=0.02)
+        # Verify the regenerated body contains boolean clipping (roof clipping).
+        space = ifc.by_id(2363)
+        body = ifcopenshell.util.representation.get_representation(space, "Model", "Body", "MODEL_VIEW")
+        assert body is not None
+        boolean_items = [i for i in (body.Items or []) if i.is_a("IfcBooleanClippingResult")]
+        assert len(boolean_items) >= 1, "Expected roof clipping but got no boolean result"
 
     def test_regenerate_space_twice_does_not_duplicate_half_spaces(self):
         ifc = self.load_house_with_garage()

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

@@ -302,15 +302,22 @@ def get_vertical_bounding_planes(
     bounds = space_polygon.bounds
     cx = (bounds[0] + bounds[2]) / 2.0
     cy = (bounds[1] + bounds[3]) / 2.0
-    sample_offsets = [(0.0, 0.0)]
+    sample_points = [(cx, cy)]
     if bounds[2] - bounds[0] > 0.1:
-        sample_offsets.append((0.25 * (bounds[2] - bounds[0]), 0.0))
+        sample_points.append((cx + 0.25 * (bounds[2] - bounds[0]), cy))
-        sample_offsets.append((-0.25 * (bounds[2] - bounds[0]), 0.0))
+        sample_points.append((cx - 0.25 * (bounds[2] - bounds[0]), cy))
     if bounds[3] - bounds[1] > 0.1:
-        sample_offsets.append((0.0, 0.25 * (bounds[3] - bounds[1])))
+        sample_points.append((cx, cy + 0.25 * (bounds[3] - bounds[1])))
-        sample_offsets.append((0.0, -0.25 * (bounds[3] - bounds[1])))
+        sample_points.append((cx, cy - 0.25 * (bounds[3] - bounds[1])))
 
-    hits = _nearest_ray_hits(tree, [(cx + dx, cy + dy, origin_z) for dx, dy in sample_offsets], ray_dir)
+    # Sample from footprint corners, offset toward centroid so the ray origin
+    # sits inside the space (not on a bounding wall).  This catches elements
+    # (e.g. sloped roofs) that only cover a corner of the space.
+    for coords in space_polygon.exterior.coords[:-1]:
+        vx, vy = coords[0], coords[1]
+        sample_points.append((vx + 0.05 * (cx - vx), vy + 0.05 * (cy - vy)))
+
+    hits = _nearest_ray_hits(tree, [(x, y, origin_z) for x, y in sample_points], ray_dir)
     if not hits:
         return "EXTRUDE_CLIP", []  # open top / void below: no bounding planes