create a setting to produce pythonOCC shapes for ifcopenshell.geom.iterator and -create_shape()

src/ifcopenshell-python/ifcopenshell/geom/__init__.py

@@ -22,7 +22,33 @@ import sys
 
 from .. import ifcopenshell_wrapper
 
-settings = ifcopenshell_wrapper.settings
+def has_occ():
+    try: import OCC.BRepTools
+    except: return False
+    return True
+
+
+has_occ = has_occ()
+wrap_shape_creation = lambda settings, shape: shape
+if has_occ:
+    import occ_utils as utils
+    wrap_shape_creation = lambda settings, shape: utils.create_shape_from_serialization(shape) if getattr(settings, 'use_python_opencascade', False) else shape
+
+
+# Subclass the settings module to provide an additional
+# setting to enable pythonOCC when available
+class settings(ifcopenshell_wrapper.settings):
+    if has_occ:
+        USE_PYTHON_OPENCASCADE = -1
+        def set(self, *args):
+            setting, value = args
+            if setting == settings.USE_PYTHON_OPENCASCADE:
+                self.set(settings.USE_BREP_DATA, value)
+                self.set(settings.DISABLE_TRIANGULATION, value)
+                self.use_python_opencascade = value
+            else:
+                ifcopenshell_wrapper.settings.set(self, *args)
+
 
 # Hide templating precision to the user by choosing based on Python's 
 # internal float type. This is probably always going to be a double.
@@ -34,11 +60,15 @@ for ty in (ifcopenshell_wrapper.iterator_single_precision, ifcopenshell_wrapper.
 # Make sure people are able to use python's platform agnostic paths
 class iterator(_iterator):
     def __init__(self, settings, filename):
+        self.settings = settings
         _iterator.__init__(self, settings, os.path.abspath(filename))
+    if has_occ:
+        def get(self):
+            return wrap_shape_creation(self.settings, _iterator.get(self))
 
 
 def create_shape(settings, inst): 
-    return ifcopenshell_wrapper.create_shape(settings, inst.wrapped_data)
+    return wrap_shape_creation(settings, ifcopenshell_wrapper.create_shape(settings, inst.wrapped_data))
 
 
 def iterate(settings, filename):
@@ -47,3 +77,5 @@ def iterate(settings, filename):
         while True:
             yield it.get()
             if not it.next(): break
+
+

src/ifcopenshell-python/ifcopenshell/geom/occ_utils.py

@@ -0,0 +1,66 @@
+import random
+from collections import namedtuple
+
+import OCC.gp
+import OCC.V3d
+import OCC.Quantity
+import OCC.BRepTools
+import OCC.Display.SimpleGui
+
+tuple = namedtuple('shape', ('data', 'geometry'))
+
+handle, main_loop, add_menu, add_function_to_menu = None, None, None, None
+
+def initialize_display():
+    global handle, main_loop, add_menu, add_function_to_menu
+    handle, main_loop, add_menu, add_function_to_menu = OCC.Display.SimpleGui.init_display()
+
+    def setup():
+        viewer_handle = handle.GetViewer()
+        viewer = viewer_handle.GetObject()
+        while True:
+            viewer.InitActiveLights()
+            try: active_light = viewer.ActiveLight()
+            except: break
+            viewer.DelLight(active_light)
+            viewer.NextActiveLights()
+        for dir in [(1,2,-3), (-2,-1,1)]:
+            light = OCC.V3d.V3d_DirectionalLight(viewer_handle)
+            light.SetDirection(*dir)
+            viewer.SetLightOn(light.GetHandle())
+    setup()
+    return handle
+
+
+def display_shape(shape, clr=None):
+    if not clr: 
+        r = lambda: random.random() * 0.3 + 0.7
+        clr = OCC.Quantity.Quantity_Color(r(), r(), r(), OCC.Quantity.Quantity_TOC_RGB)
+    return handle.DisplayShape(shape, color=clr, update=True)
+
+
+def set_shape_transparency(ais, t):
+    handle.Context.SetTransparency(ais, t)
+
+
+def get_bounding_box_center(bbox):
+    bbmin = [0.]*3; bbmax = [0.]*3
+    bbmin[0], bbmin[1], bbmin[2], bbmax[0], bbmax[1], bbmax[2] = bbox.Get()
+    return OCC.gp.gp_Pnt(*map(lambda xy: (xy[0]+xy[1])/2., zip(bbmin, bbmax)))
+
+
+def create_shape_from_serialization(brep_object):
+    brep_data, occ_shape = None, None
+    
+    try: brep_data = brep_object.geometry.brep_data
+    except: pass    
+    if not brep_data: return tuple(brep_object, None)
+    
+    try:
+        ss = OCC.BRepTools.BRepTools_ShapeSet()
+        ss.ReadFromString(brep_data)
+        occ_shape = ss.Shape(ss.NbShapes())
+    except: pass
+    
+    return tuple(brep_object, occ_shape)
+