importIFCHelper.py

# ***************************************************************************
# *                                                                         *
# *   Copyright (c) 2019                                                    *
# *   Yorik van Havre <yorik@uncreated.net>                                 *
# *                                                                         *
# *   This program is free software; you can redistribute it and/or modify  *
# *   it under the terms of the GNU Lesser General Public License (LGPL)    *
# *   as published by the Free Software Foundation; either version 2 of     *
# *   the License, or (at your option) any later version.                   *
# *   for detail see the LICENCE text file.                                 *
# *                                                                         *
# *   This program is distributed in the hope that it will be useful,       *
# *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
# *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
# *   GNU Library General Public License for more details.                  *
# *                                                                         *
# *   You should have received a copy of the GNU Library General Public     *
# *   License along with this program; if not, write to the Free Software   *
# *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  *
# *   USA                                                                   *
# *                                                                         *
# ***************************************************************************

import six
import sys
import math

import FreeCAD
import Arch
import ArchIFC


# ************************************************************************************************
# ********** some helper, used in import and export, or should stay together
def decode(filename,utf=False):

    "turns unicodes into strings"

    if six.PY2 and isinstance(filename,six.text_type):
        # workaround since ifcopenshell currently can't handle unicode filenames
        encoding = "utf8" if utf else sys.getfilesystemencoding()
        filename = filename.encode(encoding)
    return filename


# used in export
def dd2dms(dd):

    "converts decimal degrees to degrees,minutes,seconds"

    dd = abs(dd)
    minutes,seconds = divmod(dd*3600,60)
    degrees,minutes = divmod(minutes,60)
    if dd < 0:
        degrees = -degrees
    return (int(degrees),int(minutes),int(seconds))


# used in import
def dms2dd(degrees, minutes, seconds, milliseconds=0):

    "converts degrees,minutes,seconds to decimal degrees"

    dd = float(degrees) + float(minutes)/60 + float(seconds)/(3600)
    return dd


# ************************************************************************************************
# ********** some helper, mainly used in import
class ProjectImporter:
    """A helper class to create a FreeCAD Arch Project object"""

    def __init__(self, file, objects):
        self.file = file
        self.objects = objects

    def execute(self):
        self.project = self.file.by_type("IfcProject")[0]
        self.object = Arch.makeProject()
        self.objects[self.project.id()] = self.object
        self.setAttributes()
        self.setComplexAttributes()

    def setAttributes(self):
        for property in self.object.PropertiesList:
            if hasattr(self.project, property) and getattr(self.project, property):
                setattr(self.object, property, getattr(self.project, property))

    def setComplexAttributes(self):
        try:
            mapConversion = self.project.RepresentationContexts[0].HasCoordinateOperation[0]

            data = self.extractTargetCRSData(mapConversion.TargetCRS)
            data.update(self.extractMapConversionData(mapConversion))
            ArchIFC.IfcRoot.setObjIfcComplexAttributeValue(self, self.object, "RepresentationContexts", data)
        except:
            # This scenario occurs validly in IFC2X3, as the mapConversion does
            # not exist
            return

    def extractTargetCRSData(self, targetCRS):
        mappings = {
            "name": "Name",
            "description": "Description",
            "geodetic_datum": "GeodeticDatum",
            "vertical_datum": "VerticalDatum",
            "map_projection": "MapProjection",
            "map_zone": "MapZone"
        }
        data = {}
        for attributeName, ifcName in mappings.items():
            data[attributeName] = str(getattr(targetCRS, ifcName))

        if targetCRS.MapUnit.Prefix:
            data["map_unit"] = targetCRS.MapUnit.Prefix.title() + targetCRS.MapUnit.Name.lower()
        else:
            data["map_unit"] = targetCRS.MapUnit.Name.title()

        return data

    def extractMapConversionData(self, mapConversion):
        mappings = {
            "eastings": "Eastings",
            "northings": "Northings",
            "orthogonal_height": "OrthogonalHeight",
            "x_axis_abscissa": "XAxisAbscissa",
            "x_axis_ordinate": "XAxisOrdinate",
            "scale": "Scale"
        }
        data = {}
        for attributeName, ifcName in mappings.items():
            data[attributeName] = str(getattr(mapConversion, ifcName))

        data["true_north"] = str(self.calculateTrueNorthAngle(
            mapConversion.XAxisAbscissa, mapConversion.XAxisOrdinate))
        return data

    def calculateTrueNorthAngle(self, x, y):
        return round(math.degrees(math.atan2(y, x)) - 90, 6)


# type tables
def buildRelProductsAnnotations(ifcfile, root_element):
    """build the products and annotations relation table and"""

    # products
    products = ifcfile.by_type(root_element)

    # annotations
    annotations = ifcfile.by_type("IfcAnnotation")
    tp = []
    for product in products:
        if product.is_a("IfcGrid") and not (product in annotations):
            annotations.append(product)
        elif not (product in annotations):
            tp.append(product)

    # remove any leftover annotations from products
    products = sorted(tp,key=lambda prod: prod.id())

    return products, annotations


# relation tables
def buildRelProductRepresentation(ifcfile):
    """build the product/representations relation table"""

    prodrepr = {}  # product/representations table

    for p in ifcfile.by_type("IfcProduct"):
        if hasattr(p,"Representation"):
            if p.Representation:
                for it in p.Representation.Representations:
                    for it1 in it.Items:
                        prodrepr.setdefault(p.id(),[]).append(it1.id())
                        if it1.is_a("IfcBooleanResult"):
                            prodrepr.setdefault(p.id(),[]).append(it1.FirstOperand.id())
                        elif it.Items[0].is_a("IfcMappedItem"):
                            prodrepr.setdefault(p.id(),[]).append(it1.MappingSource.MappedRepresentation.id())
                            if it1.MappingSource.MappedRepresentation.is_a("IfcShapeRepresentation"):
                                for it2 in it1.MappingSource.MappedRepresentation.Items:
                                    prodrepr.setdefault(p.id(),[]).append(it2.id())

    return prodrepr


def buildRelAdditions(ifcfile):
    """build the additions relation table"""

    additions = {}  # { host:[child,...], ... }

    for r in ifcfile.by_type("IfcRelContainedInSpatialStructure"):
        additions.setdefault(r.RelatingStructure.id(),[]).extend([e.id() for e in r.RelatedElements])
    for r in ifcfile.by_type("IfcRelAggregates"):
        additions.setdefault(r.RelatingObject.id(),[]).extend([e.id() for e in r.RelatedObjects])

    return additions


def buildRelGroups(ifcfile):
    """build the groups relation table"""

    groups = {}  # { host:[child,...], ... }     # used in structural IFC

    for r in ifcfile.by_type("IfcRelAssignsToGroup"):
        groups.setdefault(r.RelatingGroup.id(),[]).extend([e.id() for e in r.RelatedObjects])

    return groups


def buildRelSubtractions(ifcfile):
    """build the subtractions relation table"""

    subtractions = []  # [ [opening,host], ... ]

    for r in ifcfile.by_type("IfcRelVoidsElement"):
        subtractions.append([r.RelatedOpeningElement.id(), r.RelatingBuildingElement.id()])

    return subtractions


def buildRelMattable(ifcfile):
    """build the mattable relation table"""

    mattable = {}  # { objid:matid }

    for r in ifcfile.by_type("IfcRelAssociatesMaterial"):
        for o in r.RelatedObjects:
            if r.RelatingMaterial.is_a("IfcMaterial"):
                mattable[o.id()] = r.RelatingMaterial.id()
            elif r.RelatingMaterial.is_a("IfcMaterialLayer"):
                mattable[o.id()] = r.RelatingMaterial.Material.id()
            elif r.RelatingMaterial.is_a("IfcMaterialLayerSet"):
                mattable[o.id()] = r.RelatingMaterial.MaterialLayers[0].Material.id()
            elif r.RelatingMaterial.is_a("IfcMaterialLayerSetUsage"):
                mattable[o.id()] = r.RelatingMaterial.ForLayerSet.MaterialLayers[0].Material.id()

    return mattable


# ************************************************************************************************
# color relation tables
# products can have a color and materials can have a color and products can have a material
# colors for material assigned to a product and product color can be different
def buildRelColors(ifcfile, prodrepr):
    """build the colors relation table and"""

    # returns all IfcStyledItem colors, material and product colors
    colors = {}  # { id:(r,g,b) }
    style_material_id = {}  # { style_entity_id: material_id) }

    # get style_color_rgb table
    style_color_rgb = {}  # { style_entity_id: (r,g,b) }
    for r in ifcfile.by_type("IfcStyledItem"):
        if r.Styles:
            if r.Styles[0].is_a("IfcPresentationStyleAssignment"):
                for style1 in r.Styles[0].Styles:
                    if style1.is_a("IfcSurfaceStyle"):
                        for style2 in style1.Styles:
                            if style2.is_a("IfcSurfaceStyleRendering"):
                                if style2.SurfaceColour:
                                    c = style2.SurfaceColour
                                    style_color_rgb[r.id()] = (c.Red,c.Green,c.Blue)

        # Nova
        # FIXME: style_entity_id = { style_entity_id: product_id } not material_id ???
        # see https://forum.freecadweb.org/viewtopic.php?f=39&t=37940&start=10#p329491
        # last code change in these color code https://github.com/FreeCAD/FreeCAD/commit/2d1f6ab1
        '''
        if r.Item:
            # print(r.id())
            # print(r.Item)  # IfcRepresentationItem or IfcShapeRepresentation
            for p in prodrepr.keys():
                if r.Item.id() in prodrepr[p]:
                    style_material_id[r.id()] = p
                    # print(p)
                    # print(ifcfile[p])  # product
        '''
    # a much faster version for Nova style_material_id with product_ids
    # no material colors, Nova ifc files often do not have materials at all
    for p in prodrepr.keys():
        # print("\n")
        # print(ifcfile[p])  # IfcProduct
        # print(ifcfile[p].Representation)  # IfcProductDefinitionShape
        # print(ifcfile[p].Representation.Representations[0])  # IfcShapeRepresentation
        # print(ifcfile[p].Representation.Representations[0].Items[0])  # IfcRepresentationItem
        # print(ifcfile[p].Representation.Representations[0].Items[0].StyledByItem[0])  # IfcStyledItem
        # print(ifcfile[p].Representation.Representations[0].Items[0].StyledByItem[0].id())
        # print(p)
        representation_item = ifcfile[p].Representation.Representations[0].Items[0]
        if hasattr(representation_item, "StyledByItem") and representation_item.StyledByItem:
            style_material_id[representation_item.StyledByItem[0].id()] = p

    # Allplan, ArchiCAD
    for m in ifcfile.by_type("IfcMaterialDefinitionRepresentation"):
        for it in m.Representations:
            if it.Items:
                style_material_id[it.Items[0].id()] = m.RepresentedMaterial.id()

    # create colors out of style_color_rgb and style_material_id
    for k in style_material_id:
        if k in style_color_rgb:
            colors[style_material_id[k]] = style_color_rgb[k]

    return colors


def buildRelProductColors(ifcfile, prodrepr):

    # gets the colors for the products
    colors = {}  # { id:(r,g,b) }

    for p in prodrepr.keys():

        # print(p)

        # representation item, see docu IfcRepresentationItem
        # all kind of geometric or topological representation items
        # IfcExtrudedAreaSolid, IfcMappedItem, IfcFacetedBrep, IfcBooleanResult, etc
        representation_item = ifcfile[p].Representation.Representations[0].Items[0]
        # print(representation_item)

        # get the geometric representations which have a presentation style
        # all representation items have the inverse attribute StyledByItem for this
        # there will be gemetric representations which do not have a presentation style
        # the StyledByItem will be empty than
        if representation_item.StyledByItem:

            # it has to be a IfcStyledItem, no check needed
            styled_item = representation_item.StyledByItem[0]

            # write into colors table if a IfcStyledItem exists for this product
            # write None if something goes wrong or if the ifc file has errors and thus no valid color is returned
            colors[p] = getColorFromStyledItem(styled_item)

    return colors


def buildRelMaterialColors(ifcfile, prodrepr):
    # not implemented
    pass


def getColorFromStyledItem(styled_item):

    # styled_item should be a IfcStyledItem
    if not styled_item.is_a("IfcStyledItem"):
        print("Not a IfcStyledItem passed.")
        return None

    rgb_color = None

    # print(styled_item)
    # The IfcStyledItem holds presentation style information for products,
    # either explicitly for an IfcGeometricRepresentationItem being part of
    # an IfcShapeRepresentation assigned to a product, or by assigning presentation
    # information to IfcMaterial being assigned as other representation for a product.

    # In current IFC release (IFC2x3) only one presentation style assignment shall be assigned.

    if len(styled_item.Styles) != 1:
        if len(styled_item.Styles) == 0:
            pass
            # ca 100x in 210_King_Merged.ifc
            # empty styles, #4952778=IfcStyledItem(#4952779,(),$)
            # this is an error in the ifc file IMHO
            # print(ifcfile[p])
            # print(styled_item)
            # print(styled_item.Styles)
        else:
            pass
            # never seen an ifc with more than one Styles in IfcStyledItem
    else:
        # get the IfcPresentationStyleAssignment, there should only be one, see above
        assign_style = styled_item.Styles[0]
        # print(assign_style)  # IfcPresentationStyleAssignment

        # IfcPresentationStyleAssignment can hold various kinde and count of styles
        # see IfcPresentationStyleSelect
        if assign_style.Styles[0].is_a("IfcSurfaceStyle"):
            # Schependomlaan and Nova and others
            # print(assign_style.Styles[0].Styles[0])  # IfcSurfaceStyleRendering
            rgb_color = assign_style.Styles[0].Styles[0].SurfaceColour  # IfcColourRgb
            # print(rgb_color)
        elif assign_style.Styles[0].is_a("IfcCurveStyle"):
            if (
                len(assign_style.Styles) == 2
                and assign_style.Styles[1].is_a("IfcSurfaceStyle")
            ):
                # Allplan, new IFC export started in 2017
                # print(assign_style.Styles[0].CurveColour)  # IfcDraughtingPreDefinedColour
                # on index 1 ist das was wir brauchen !!!
                rgb_color = assign_style.Styles[1].Styles[0].SurfaceColour
                # print(rgb_color)
            else:
                # 2x Annotations in 210_King_Merged.ifc
                # print(ifcfile[p])
                # print(assign_style.Styles[0])
                # print(assign_style.Styles[0].CurveColour)
                rgb_color = assign_style.Styles[0].CurveColour

    if rgb_color is not None:
        col = rgb_color.Red, rgb_color.Green, rgb_color.Blue
        # print(col)
    else:
        col = None

    return col


# ************************************************************************************************
# property related methods
def buildRelProperties(ifcfile):
    """
    Builds and returns a dictionary of {object:[properties]} from an IFC file
    """

    # this method no longer used by the importer module
    # but this relation table might be useful anyway for other purposes

    properties = {}  # { objid : { psetid : [propertyid, ... ], ... }, ... }
    for r in ifcfile.by_type("IfcRelDefinesByProperties"):
        for obj in r.RelatedObjects:
            if not obj.id() in properties:
                properties[obj.id()] = {}
            psets = {}
            props = []
            if r.RelatingPropertyDefinition.is_a("IfcPropertySet"):
                props.extend([prop.id() for prop in r.RelatingPropertyDefinition.HasProperties])
                psets[r.RelatingPropertyDefinition.id()] = props
                properties[obj.id()].update(psets)
    return properties


def getIfcPropertySets(ifcfile, pid):
    """Returns a dicionary of {pset_id:[prop_id, prop_id...]} for an IFC object"""

    # get psets for this pid
    psets = {}
    for rel in ifcfile[pid].IsDefinedBy:
        # the following if condition is needed in IFC2x3 only
        # https://forum.freecadweb.org/viewtopic.php?f=39&t=37892#p322884
        if rel.is_a('IfcRelDefinesByProperties'):
            props = []
            if rel.RelatingPropertyDefinition.is_a("IfcPropertySet"):
                props.extend([prop.id() for prop in rel.RelatingPropertyDefinition.HasProperties])
                psets[rel.RelatingPropertyDefinition.id()] = props
    return psets


def getIfcProperties(ifcfile, pid, psets, d):
    """builds valid property values for FreeCAD"""

    for pset in psets.keys():
        # print("reading pset: ",pset)
        psetname = ifcfile[pset].Name
        if six.PY2:
            psetname = psetname.encode("utf8")
        for prop in psets[pset]:
            e = ifcfile[prop]
            pname = e.Name
            if six.PY2:
                pname = pname.encode("utf8")
            if e.is_a("IfcPropertySingleValue"):
                if e.NominalValue:
                    ptype = e.NominalValue.is_a()
                    if ptype in ['IfcLabel','IfcText','IfcIdentifier','IfcDescriptiveMeasure']:
                        pvalue = e.NominalValue.wrappedValue
                        if six.PY2:
                            pvalue = pvalue.encode("utf8")
                    else:
                        pvalue = str(e.NominalValue.wrappedValue)
                    if hasattr(e.NominalValue,'Unit'):
                        if e.NominalValue.Unit:
                            pvalue += e.NominalValue.Unit
                    d[pname+";;"+psetname] = ptype+";;"+pvalue
                # print("adding property: ",pname,ptype,pvalue," pset ",psetname)
    return d


# ************************************************************************************************
def getScaling(ifcfile):
    """returns a scaling factor from file units to mm"""

    def getUnit(unit):
        if unit.Name == "METRE":
            if unit.Prefix == "KILO":
                return 1000000.0
            elif unit.Prefix == "HECTO":
                return 100000.0
            elif unit.Prefix == "DECA":
                return 10000.0
            elif not unit.Prefix:
                return 1000.0
            elif unit.Prefix == "DECI":
                return 100.0
            elif unit.Prefix == "CENTI":
                return 10.0
        return 1.0

    ua = ifcfile.by_type("IfcUnitAssignment")
    if not ua:
        return 1.0
    ua = ua[0]
    for u in ua.Units:
        if u.UnitType == "LENGTHUNIT":
            if u.is_a("IfcConversionBasedUnit"):
                f = getUnit(u.ConversionFactor.UnitComponent)
                return f * u.ConversionFactor.ValueComponent.wrappedValue
            elif u.is_a("IfcSIUnit") or u.is_a("IfcUnit"):
                return getUnit(u)
    return 1.0


def getRotation(entity):
    """returns a FreeCAD rotation from an IfcProduct with a IfcMappedItem representation"""
    try:
        u = FreeCAD.Vector(entity.Axis1.DirectionRatios)
        v = FreeCAD.Vector(entity.Axis2.DirectionRatios)
        w = FreeCAD.Vector(entity.Axis3.DirectionRatios)
    except AttributeError:
        return FreeCAD.Rotation()
    import WorkingPlane
    p = WorkingPlane.plane(u=u,v=v,w=w)
    return p.getRotation().Rotation


def getPlacement(entity,scaling=1000):
    """returns a placement from the given entity"""

    if not entity:
        return None
    import DraftVecUtils
    pl = None
    if entity.is_a("IfcAxis2Placement3D"):
        x = getVector(entity.RefDirection,scaling)
        z = getVector(entity.Axis,scaling)
        if x and z:
            y = z.cross(x)
            m = DraftVecUtils.getPlaneRotation(x,y,z)
            pl = FreeCAD.Placement(m)
        else:
            pl = FreeCAD.Placement()
        loc = getVector(entity.Location,scaling)
        if loc:
            pl.move(loc)
    elif entity.is_a("IfcLocalPlacement"):
        pl = getPlacement(entity.PlacementRelTo,1)  # original placement
        relpl = getPlacement(entity.RelativePlacement,1)  # relative transf
        if pl and relpl:
            pl = pl.multiply(relpl)
        elif relpl:
            pl = relpl
    elif entity.is_a("IfcCartesianPoint"):
        loc = getVector(entity,scaling)
        pl = FreeCAD.Placement()
        pl.move(loc)
    if pl:
        pl.Base = FreeCAD.Vector(pl.Base).multiply(scaling)
    return pl


def getVector(entity,scaling=1000):
    """returns a vector from the given entity"""

    if not entity:
        return None
    v = None
    if entity.is_a("IfcDirection"):
        if len(entity.DirectionRatios) == 3:
            v = FreeCAD.Vector(tuple(entity.DirectionRatios))
        else:
            v = FreeCAD.Vector(tuple(entity.DirectionRatios+[0]))
    elif entity.is_a("IfcCartesianPoint"):
        if len(entity.Coordinates) == 3:
            v = FreeCAD.Vector(tuple(entity.Coordinates))
        else:
            v = FreeCAD.Vector(tuple(entity.Coordinates+[0]))
    # if v:
    #     v.multiply(scaling)
    return v


def get2DShape(representation,scaling=1000):
    """Returns a shape from a 2D IfcShapeRepresentation"""

    import Part
    import DraftVecUtils
    import Draft

    def getPolyline(ent):
        pts = []
        for p in ent.Points:
            c = p.Coordinates
            c = FreeCAD.Vector(c[0],c[1],c[2] if len(c) > 2 else 0)
            c.multiply(scaling)
            pts.append(c)
        return Part.makePolygon(pts)

    def getLine(ent):
        pts = []
        p1 = getVector(ent.Pnt)
        p1.multiply(scaling)
        pts.append(p1)
        p2 = getVector(ent.Dir)
        p2.multiply(scaling)
        p2 = p1.add(p2)
        pts.append(p2)
        return Part.makePolygon(pts)

    def getCircle(ent):
        c = ent.Position.Location.Coordinates
        c = FreeCAD.Vector(c[0],c[1],c[2] if len(c) > 2 else 0)
        c.multiply(scaling)
        r = ent.Radius*scaling
        return Part.makeCircle(r,c)

    def getCurveSet(ent):
        result = []
        if ent.is_a() in ["IfcGeometricCurveSet","IfcGeometricSet"]:
            elts = ent.Elements
        elif ent.is_a() in ["IfcLine","IfcPolyline","IfcCircle","IfcTrimmedCurve"]:
            elts = [ent]
        for el in elts:
            if el.is_a("IfcPolyline"):
                result.append(getPolyline(el))
            elif el.is_a("IfcLine"):
                result.append(getLine(el))
            elif el.is_a("IfcCircle"):
                result.append(getCircle(el))
            elif el.is_a("IfcTrimmedCurve"):
                base = el.BasisCurve
                t1 = el.Trim1[0].wrappedValue
                t2 = el.Trim2[0].wrappedValue
                if not el.SenseAgreement:
                    t1,t2 = t2,t1
                if base.is_a("IfcPolyline"):
                    bc = getPolyline(base)
                    result.append(bc)
                elif base.is_a("IfcCircle"):
                    bc = getCircle(base)
                    e = Part.ArcOfCircle(bc.Curve,math.radians(t1),math.radians(t2)).toShape()
                    d = base.Position.RefDirection.DirectionRatios
                    v = FreeCAD.Vector(d[0],d[1],d[2] if len(d) > 2 else 0)
                    a = -DraftVecUtils.angle(v)
                    e.rotate(bc.Curve.Center,FreeCAD.Vector(0,0,1),math.degrees(a))
                    result.append(e)
            elif el.is_a("IfcCompositeCurve"):
                for base in el.Segments:
                    if base.ParentCurve.is_a("IfcPolyline"):
                        bc = getPolyline(base.ParentCurve)
                        result.append(bc)
                    elif base.ParentCurve.is_a("IfcCircle"):
                        bc = getCircle(base.ParentCurve)
                        e = Part.ArcOfCircle(bc.Curve,math.radians(t1),math.radians(t2)).toShape()
                        d = base.Position.RefDirection.DirectionRatios
                        v = FreeCAD.Vector(d[0],d[1],d[2] if len(d) > 2 else 0)
                        a = -DraftVecUtils.angle(v)
                        e.rotate(bc.Curve.Center,FreeCAD.Vector(0,0,1),math.degrees(a))
                        result.append(e)

        return result

    result = []
    if representation.is_a("IfcShapeRepresentation"):
        for item in representation.Items:
            if item.is_a() in ["IfcGeometricCurveSet","IfcGeometricSet"]:
                result = getCurveSet(item)
            elif item.is_a("IfcMappedItem"):
                preresult = get2DShape(item.MappingSource.MappedRepresentation,scaling)
                pla = getPlacement(item.MappingSource.MappingOrigin,scaling)
                rot = getRotation(item.MappingTarget)
                if pla:
                    if rot.Angle:
                        pla.Rotation = rot
                    for r in preresult:
                        # r.Placement = pla
                        result.append(r)
                else:
                    result = preresult
            elif item.is_a("IfcTextLiteral"):
                t = Draft.makeText([item.Literal],point=getPlacement(item.Placement,scaling).Base)
                return t  # dirty hack... Object creation should not be done here
    elif representation.is_a() in ["IfcPolyline","IfcCircle","IfcTrimmedCurve"]:
        result = getCurveSet(representation)
    return result