NURBS export for Blender and import for FreeCAD

blender-nurbs-selfcontained.py

#!/usr/bin/env python

freecadfunctions="""#!/usr/env/bin python
#python 2
import FreeCAD,Part
def pointstopoles1D(points):
    return zip(*[(FreeCAD.Vector(point[0:3]),point[3]) for point in points])

def pointstopoles(points,cu):
    poles=[]
    weights=[]
    for dontcare in xrange(cu):
        poles.append([])
        weights.append([])
    for i,point in enumerate(points):
        u = i % cu
        v = i // cu
        poles[u].append(FreeCAD.Vector(point[0:3]))
        weights[u].append(point[3])
    return poles,weights

def mults(npoles,degree,isperiodic=False,bezier=False,endpoint=False):
    if isperiodic: #and uniform
        multv = (1,) * (npoles +1)
    elif endpoint: #quasi-uniform
        multv=(degree+1,)+(1,)*(npoles - degree-1)+(degree+1,)
    elif bezier:
       #what OCC describes as picewise bezier
       k = 1 + (npoles -1) / degree
       multv=(degree+1,)+(degree,)*(k-2)+(degree+1,)
    else: #uniform
        multv=(1,)*(npoles+degree+1)
    #print '%s deg=%d pol=%d sum=%d' % (multv ,degree, npoles, (sum(multv)-degree-1))
    return multv

def importblenderspline(d1,doc=None,name=None,showpoles=False):
    import FreeCAD
    if name is None:
        name = 'Surface' if d1['order_v']>0 else 'Curve'
    doc = doc or FreeCAD.activeDocument() or FreeCAD.newDocument()
    obj = doc.addObject('Part::Spline',name)
    obj.Shape = blendersplinecurve(d1).toShape()
    if showpoles:
        obj.ViewObject.ControlPoints = True

def blendersplinecurve(d1):
    points=d1['points']
    cu=d1['point_count_u']
    cv=d1['point_count_v']
    degu=d1['order_u']-1
    degv=d1['order_v']-1
    uperiodic=d1['use_cyclic_u']
    vperiodic=d1['use_cyclic_v']
    if degv != -1:
        poles,weights= pointstopoles(points,cu)
        bss=Part.BSplineSurface()
        umults=mults(cu,degu,uperiodic,d1['use_bezier_u'],d1['use_endpoint_u'])
        vmults=mults(cv,degv,vperiodic,d1['use_bezier_v'],d1['use_endpoint_v'])
        if d1['use_bezier_u'] and (sum(umults)-degu-1) != cu or d1['use_bezier_v'] and (sum(vmults)-degv-1) != cv:
             raise ValueError#would fail later because of mults and points mismatch
        bss.buildFromPolesMultsKnots(poles,umults, vmults,uperiodic=uperiodic, vperiodic=vperiodic, udegree=degu, vdegree=degv, weights=weights)
        return bss
    else:
        poles,weights = pointstopoles1D(points)
        bsc=Part.BSplineCurve()
        if d1['use_bezier_u'] and degu==3: #blender is doing something very strange
            poles=poles[1:]
            weights=weights[1:]
            cu-=1
        umults=mults(cu,degu,uperiodic,d1['use_bezier_u'],d1['use_endpoint_u'])
        if d1['use_bezier_u'] and (sum(umults)-degu-1) != cu: #to many poles, 
            cu=sum(umults)-degu-1
            poles = poles[:cu]
            weights = weights[:cu]
        try:
            bsc.buildFromPolesMultsKnots(poles,umults,periodic=uperiodic,degree=degu,weights=weights)
        except:
            print umults,' ',len(poles)
            raise
        return bsc

"""
def spline2dict(spline):
    d1={}
    for attr in ('order_u', 'order_v', 'point_count_u', 'point_count_v',\
        'use_bezier_u', 'use_bezier_v', 'use_cyclic_u', 'use_cyclic_v', \
        'use_endpoint_u', 'use_endpoint_v'):
        d1[attr]=spline.__getattribute__(attr)
    d1['points']=tuple((tuple(p.co) for p in spline.points))
    return d1

def selection2dictionary():
    import bpy
    nurbslist=[]
    for ob in bpy.context.selected_objects:
        if ob.type == 'SURFACE':
            name = ob.name
            data = ob.data
            if len(data.splines) == 1:
                nurbslist.append((name,spline2dict(data.splines[0])))
            else:
                raise ValueError("Not one spline")
    return nurbslist

def writeFreeCADMacro(nurbslist,filename):
    outfile=open(filename,'w')
    outfile.write(freecadfunctions)
    for name,d1 in nurbslist:
        outfile.write('importblenderspline(%s,name="%s")\n' % (repr(d1),name))
    outfile.close()

if __name__ == '__main__':
    writeFreeCADMacro(selection2dictionary(),'importnurbstofreecad.py')

Please can I have some informations for use this code?

Hello,
this Code works always well, but today gives me an error in Blender (you can see it in the image). Do you have an idea for resolve it

@gara01, I get the same error. Start Blender with administrator rights, then instead of filename write a path inside quotation marks as "C:\myExportedNurbs.py".
After that open this file as Macro inside Freecad et voilat ;)