Fixed step import of assembly Issue #671

src/build123d/importers.py

@@ -69,7 +69,7 @@
 from svgpathtools import svg2paths
 import unicodedata
 
-from build123d.geometry import Color
+from build123d.geometry import Color, Location
 from build123d.topology import (
     Compound,
     Edge,
@@ -133,6 +133,7 @@ def import_step(filename: str) -> Compound:
     """
 
     def get_name(label: TDF_Label) -> str:
+        """Extract name and format"""
         name = ""
         std_name = TDataStd_Name()
         if label.FindAttribute(TDataStd_Name.GetID_s(), std_name):
@@ -142,6 +143,7 @@ def get_name(label: TDF_Label) -> str:
         return clean_name.translate(str.maketrans(" .()", "____"))
 
     def get_color(shape: TopoDS_Shape) -> Quantity_ColorRGBA:
+        """Get the color - take that of the largest Face if multiple"""
 
         def get_col(obj: TopoDS_Shape) -> Quantity_ColorRGBA:
             col = Quantity_ColorRGBA()
@@ -172,37 +174,34 @@ def get_col(obj: TopoDS_Shape) -> Quantity_ColorRGBA:
 
         return shape_color
 
-    def build_assembly(
-        assembly: Compound, parent_tdf_label: Optional[TDF_Label] = None
-    ) -> list[Shape]:
-        tdf_labels = TDF_LabelSequence()
+    def build_assembly(parent_tdf_label: Optional[TDF_Label] = None) -> list[Shape]:
+        """Recursively extract object into an assembly"""
+        sub_tdf_labels = TDF_LabelSequence()
         if parent_tdf_label is None:
-            shape_tool.GetFreeShapes(tdf_labels)
+            shape_tool.GetFreeShapes(sub_tdf_labels)
         else:
-            shape_tool.GetComponents_s(parent_tdf_label, tdf_labels)
+            shape_tool.GetComponents_s(parent_tdf_label, sub_tdf_labels)
 
         sub_shapes: list[Shape] = []
-        for i in range(tdf_labels.Length()):
-            sub_tdf_label = tdf_labels.Value(i + 1)
+        for i in range(sub_tdf_labels.Length()):
+            sub_tdf_label = sub_tdf_labels.Value(i + 1)
             if shape_tool.IsReference_s(sub_tdf_label):
                 ref_tdf_label = TDF_Label()
                 shape_tool.GetReferredShape_s(sub_tdf_label, ref_tdf_label)
             else:
                 ref_tdf_label = sub_tdf_label
-            topo_shape = downcast(shape_tool.GetShape_s(ref_tdf_label))
-            sub_shape_type = topods_lut[type(topo_shape)]
-            sub_shape_loc = shape_tool.GetLocation_s(sub_tdf_label)
-            # The location of this part is relative to its parent
-            if assembly.wrapped is not None:
-                sub_shape_loc = assembly.location.wrapped.Multiplied(sub_shape_loc)
-            sub_shape: Shape = sub_shape_type()
-            sub_shape.wrapped = downcast(topo_shape.Moved(sub_shape_loc))
-            sub_shape.color = Color(get_color(topo_shape))
-            sub_shape.label = get_name(ref_tdf_label)
 
-            sub_shape.parent = assembly
+            sub_topo_shape = downcast(shape_tool.GetShape_s(ref_tdf_label))
             if shape_tool.IsAssembly_s(ref_tdf_label):
-                sub_shape.children = build_assembly(sub_shape, ref_tdf_label)
+                sub_shape = Compound()
+                sub_shape.children = build_assembly(ref_tdf_label)
+            else:
+                sub_shape = topods_lut[type(sub_topo_shape)](sub_topo_shape)
+
+            sub_shape.color = Color(get_color(sub_topo_shape))
+            sub_shape.label = get_name(ref_tdf_label)
+            sub_shape.move(Location(shape_tool.GetLocation_s(sub_tdf_label)))
+
             sub_shapes.append(sub_shape)
         return sub_shapes
 
@@ -222,7 +221,7 @@ def build_assembly(
 
     root = Compound()
     root.for_construction = None
-    build_assembly(root)
+    root.children = build_assembly()
     # Remove empty Compound wrapper if single free object
     if len(root.children) == 1:
         root = root.children[0]

tests/test_importers.py

@@ -1,6 +1,7 @@
 from io import StringIO
 import os
 import unittest
+import urllib.request
 from build123d import BuildLine, Color, Line, Bezier, RadiusArc, Solid, Compound
 from build123d.importers import (
     import_svg_as_buildline_code,
@@ -103,6 +104,21 @@ def test_bad_filename(self):
 
 
 class ImportSTEP(unittest.TestCase):
+
+    @classmethod
+    def setUpClass(cls):
+        """setUpClass is a class method that is executed once for the entire test
+        class before any of the test methods in the class are executed. It's intended
+        for setting up expensive resources or doing tasks that are required by all
+        tests in the class, such as downloading a large file, establishing a database
+        connection, or starting a server.
+        """
+        url = "https://raw.githubusercontent.com/tpaviot/pythonocc-demos/master/assets/models/as1-oc-214.stp"
+        file_path = "/tmp/as1-oc-214.stp"
+        if not os.path.exists(file_path):
+            urllib.request.urlretrieve(url, file_path)
+        cls.large_step_file_path = file_path
+
     def test_single_object(self):
         export_step(Solid.make_box(1, 1, 1), "test.step")
         box = import_step("test.step")
@@ -146,6 +162,12 @@ def test_single_label_color(self):
         self.assertEqual(imported_assembly.children[1].label, "box")
         self.assertEqual(tuple(imported_assembly.children[1].color), (0, 0, 1, 1))
 
+    def test_assembly_with_oriented_parts(self):
+        assembly = import_step(self.large_step_file_path)
+        fused = Solid.fuse(*assembly.solids())
+        # If the parts where placed correctly they all touch and can be fused
+        self.assertEqual(len(fused.solids()), 1)
+
 
 if __name__ == "__main__":
     unittest.main()