From f688133bfb990628a95f53ed32a76b5322478d60 Mon Sep 17 00:00:00 2001
From: adam-urbanczyk <13981538+adam-urbanczyk@users.noreply.github.com>
Date: Thu, 16 Jul 2026 21:07:51 +0200
Subject: [PATCH 1/6] Better imprint for assy

---
 cadquery/occ_impl/assembly.py | 30 +++++++++++++++++++-----------
 1 file changed, 19 insertions(+), 11 deletions(-)

diff --git a/cadquery/occ_impl/assembly.py b/cadquery/occ_impl/assembly.py
index d2485e612..8fabd162b 100644
--- a/cadquery/occ_impl/assembly.py
+++ b/cadquery/occ_impl/assembly.py
@@ -37,7 +37,7 @@
 )
 from OCP.BRepAlgoAPI import BRepAlgoAPI_Fuse
 from OCP.TopTools import TopTools_ListOfShape
-from OCP.BOPAlgo import BOPAlgo_GlueEnum, BOPAlgo_MakeConnected
+from OCP.BOPAlgo import BOPAlgo_GlueEnum, BOPAlgo_Builder
 from OCP.TopoDS import TopoDS_Shape
 from OCP.gp import gp_EulerSequence
 
@@ -49,7 +49,7 @@
 )
 
 from .geom import Location
-from .shapes import Shape, Solid, Compound
+from .shapes import Shape, Solid, Compound, GlueLiteral, _set_glue, _set_builder_options
 from .exporters.vtk import toString, extractEdgesFaces
 from ..cq import Workplane
 from ..utils import BiDict
@@ -855,7 +855,9 @@ def toFusedCAF(
     return top_level_lbl, doc
 
 
-def imprint(assy: AssemblyProtocol) -> Tuple[Shape, Dict[Shape, Tuple[str, ...]]]:
+def imprint(
+    assy: AssemblyProtocol, tol: float = 0.0, glue: GlueLiteral = "full",
+) -> Tuple[Shape, Dict[Shape, Tuple[str, ...]]]:
     """
     Imprint all the solids and construct a dictionary mapping imprinted solids to names from the input assy.
     """
@@ -868,22 +870,28 @@ def imprint(assy: AssemblyProtocol) -> Tuple[Shape, Dict[Shape, Tuple[str, ...]]
             id_map[s] = name
 
     # connect topologically
-    bldr = BOPAlgo_MakeConnected()
-    bldr.SetRunParallel(True)
-    bldr.SetUseOBB(True)
+    builder = BOPAlgo_Builder()
+
+    _set_glue(builder, glue)
+    _set_builder_options(builder, tol)
 
     for obj in id_map:
-        bldr.AddArgument(obj.wrapped)
+        builder.AddArgument(obj.wrapped)
 
-    bldr.Perform()
-    res = Shape(bldr.Shape())
+    builder.Perform()
+    res = Shape(builder.Shape())
 
     # make the connected solid -> id map
+    ocp_origins = builder.Origins()
     origins: Dict[Shape, Tuple[str, ...]] = {}
 
     for s in res.Solids():
-        ids = tuple(id_map[Solid(el)] for el in bldr.GetOrigins(s.wrapped))
-        # if GetOrigins yields nothing, solid was not modified
+        if ocp_origins.IsBound(s.wrapped):
+            # if GetOrigins yields nothing, solid was not modified
+            ids = tuple(id_map[Solid(el)] for el in ocp_origins.Find(s.wrapped))
+        else:
+            ids = ()
+
         origins[s] = ids if ids else (id_map[s],)
 
     return res, origins

From a4acc30c190525614c1ecfcd6c6d5944c1c18532 Mon Sep 17 00:00:00 2001
From: adam-urbanczyk <13981538+adam-urbanczyk@users.noreply.github.com>
Date: Fri, 17 Jul 2026 11:26:38 +0200
Subject: [PATCH 2/6] Typing fix

---
 cadquery/occ_impl/nurbs.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/cadquery/occ_impl/nurbs.py b/cadquery/occ_impl/nurbs.py
index 4a958d35f..9f77b1949 100644
--- a/cadquery/occ_impl/nurbs.py
+++ b/cadquery/occ_impl/nurbs.py
@@ -357,7 +357,7 @@ def isoline(self, param: float, dir: Literal["u", "v"] = "u") -> Curve:
 @njiti
 def _preprocess(
     u: Array, order: int, knots: Array, periodic: bool
-) -> Tuple[Array, Array, Optional[int], Optional[int], int]:
+) -> Tuple[Array, Array, int, int, int]:
     """
     Helper for handling periodicity. This function extends the knot vector,
     wraps the parameters and calculates the delta span.

From bd53fc8d6bb971f40ac0ebf9699f514f15d0ec44 Mon Sep 17 00:00:00 2001
From: adam-urbanczyk <13981538+adam-urbanczyk@users.noreply.github.com>
Date: Fri, 17 Jul 2026 15:17:19 +0200
Subject: [PATCH 3/6] Add a note about glue and threads.

---
 cadquery/occ_impl/assembly.py | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/cadquery/occ_impl/assembly.py b/cadquery/occ_impl/assembly.py
index 8fabd162b..eb22cc811 100644
--- a/cadquery/occ_impl/assembly.py
+++ b/cadquery/occ_impl/assembly.py
@@ -860,6 +860,9 @@ def imprint(
 ) -> Tuple[Shape, Dict[Shape, Tuple[str, ...]]]:
     """
     Imprint all the solids and construct a dictionary mapping imprinted solids to names from the input assy.
+
+    Depending on the use case, it might be required do use different `glue` option. Moreover, for large models
+    it might be needed to limit the number of threads using :meth:`cadquery.func.setThreads`
     """
 
     # make the id map

From f66dbfb442fd6acd4202b5f418b757f976056c7b Mon Sep 17 00:00:00 2001
From: adam-urbanczyk <13981538+adam-urbanczyk@users.noreply.github.com>
Date: Fri, 24 Jul 2026 13:52:17 +0200
Subject: [PATCH 4/6] Tweak comments and docstrings

---
 cadquery/occ_impl/assembly.py | 2 +-
 cadquery/occ_impl/shapes.py   | 3 +++
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/cadquery/occ_impl/assembly.py b/cadquery/occ_impl/assembly.py
index eb22cc811..ad991d6d4 100644
--- a/cadquery/occ_impl/assembly.py
+++ b/cadquery/occ_impl/assembly.py
@@ -890,7 +890,7 @@ def imprint(
 
     for s in res.Solids():
         if ocp_origins.IsBound(s.wrapped):
-            # if GetOrigins yields nothing, solid was not modified
+            # if ocp_origins does not contain the solid, it was not modified
             ids = tuple(id_map[Solid(el)] for el in ocp_origins.Find(s.wrapped))
         else:
             ids = ()
diff --git a/cadquery/occ_impl/shapes.py b/cadquery/occ_impl/shapes.py
index 7d3c665a9..d20c17c8b 100644
--- a/cadquery/occ_impl/shapes.py
+++ b/cadquery/occ_impl/shapes.py
@@ -6962,6 +6962,9 @@ def imprint(
 ) -> Shape:
     """
     Imprint arbitrary number of shapes.
+
+    Depending on the use case, it might be required do use different `glue` option. Moreover, for large models
+    it might be needed to limit the number of threads using :meth:`cadquery.func.setThreads`
     """
 
     builder = BOPAlgo_Builder()

From 4d80f4c5ed509faed0b3099684cd43742e1368db Mon Sep 17 00:00:00 2001
From: adam-urbanczyk <13981538+adam-urbanczyk@users.noreply.github.com>
Date: Fri, 24 Jul 2026 14:08:29 +0200
Subject: [PATCH 5/6] Add a test for subassy imprinting

---
 tests/test_assembly.py | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/tests/test_assembly.py b/tests/test_assembly.py
index 08d4a5f21..35da309da 100644
--- a/tests/test_assembly.py
+++ b/tests/test_assembly.py
@@ -10,6 +10,8 @@
 from pytest import approx
 
 import cadquery as cq
+
+from cadquery import Location
 from cadquery.occ_impl.exporters.assembly import (
     exportAssembly,
     exportStepMeta,
@@ -2324,6 +2326,16 @@ def touching_assy():
     return cq.Assembly().add(b1).add(b2)
 
 
+@pytest.fixture
+def complex_assy(touching_assy):
+
+    return (
+        cq.Assembly()
+        .add(touching_assy, name="sub1")
+        .add(touching_assy, loc=Location((5, 0, 0)), name="sub2")
+    )
+
+
 @pytest.fixture
 def disjoint_assy():
 
@@ -2354,6 +2366,26 @@ def test_imprinting(touching_assy, disjoint_assy):
         assert s in o
 
 
+def test_subassy_imprinting(complex_assy):
+
+    # imprint subassys separately
+    res1, origins1 = cq.occ_impl.assembly.imprint(complex_assy.sub1)
+    res2, origins2 = cq.occ_impl.assembly.imprint(complex_assy.sub2)
+
+    # reference one step imprint
+    ref, _ = cq.occ_impl.assembly.imprint(complex_assy)
+
+    # combine the results
+    res = res1 | res2
+    origins = origins1 | origins2
+
+    assert len(res.Solids()) == len(ref.Solids())
+    assert len(res.Faces()) == len(ref.Faces())
+
+    for s in res.Solids():
+        assert s in origins
+
+
 def test_order_of_transform():
 
     part = cq.Workplane().box(1, 1, 1).faces(">Z").vertices("<XY").tag("vtag")

From 48a005a15bb786ea1bdc7b28b2cb1d139131c008 Mon Sep 17 00:00:00 2001
From: adam-urbanczyk <13981538+adam-urbanczyk@users.noreply.github.com>
Date: Fri, 24 Jul 2026 14:20:54 +0200
Subject: [PATCH 6/6] Changed the default option to partial

---
 cadquery/occ_impl/assembly.py | 2 +-
 cadquery/occ_impl/shapes.py   | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/cadquery/occ_impl/assembly.py b/cadquery/occ_impl/assembly.py
index ad991d6d4..b00083d40 100644
--- a/cadquery/occ_impl/assembly.py
+++ b/cadquery/occ_impl/assembly.py
@@ -856,7 +856,7 @@ def toFusedCAF(
 
 
 def imprint(
-    assy: AssemblyProtocol, tol: float = 0.0, glue: GlueLiteral = "full",
+    assy: AssemblyProtocol, tol: float = 0.0, glue: GlueLiteral = "partial",
 ) -> Tuple[Shape, Dict[Shape, Tuple[str, ...]]]:
     """
     Imprint all the solids and construct a dictionary mapping imprinted solids to names from the input assy.
diff --git a/cadquery/occ_impl/shapes.py b/cadquery/occ_impl/shapes.py
index d20c17c8b..c2f2420ce 100644
--- a/cadquery/occ_impl/shapes.py
+++ b/cadquery/occ_impl/shapes.py
@@ -6956,7 +6956,7 @@ def enclose(
 def imprint(
     *shapes: Shape,
     tol: float = 0.0,
-    glue: GlueLiteral = "full",
+    glue: GlueLiteral = "partial",
     history: History | None = None,
     name: str | None = None,
 ) -> Shape: