This is what I have ginned up. It plots the normals to the planar 3D curves
in a step file. I'm interested in improvements.
from OCC.Utils.DataExchange.STEP import STEPImporter
from OCC.Display.SimpleGui import *
from OCC import TopAbs
from OCC.TopExp import TopExp_Explorer
from OCC.TopoDS import TopoDS
from OCC.BRep import BRep_Tool
from OCC.BRepAdaptor import BRepAdaptor_Curve
from OCC import GeomAbs
from OCC.Geom import (Handle_Geom_BSplineCurve,
Handle_Geom_Direction,
Handle_Geom_Circle,
Geom_Circle)
from OCC.GeomLProp import GeomLProp_CLProps
from OCC.Precision import Precision
from OCC import gp
from OCC.TColgp import TColgp_Array1OfPnt
from OCC.BRepBuilderAPI import BRepBuilderAPI_MakeEdge
from OCC.GeomAPI import GeomAPI_PointsToBSpline
from OCC.GeomConvert import (GeomConvert,
Convert)
import numpy as NP
def _Tcol_dim_1(li, _type):
'''function factory for 1-dimensional TCol* types'''
pts = _type(0, len(li)-1)
for n,i in enumerate(li):
pts.SetValue(n,i)
return pts
def point2d_list_to_TColgp_Array1OfPnt(li):
return _Tcol_dim_1(li, TColgp_Array1OfPnt)
def make_edge(shape):
spline = BRepBuilderAPI_MakeEdge(shape)
spline.Build()
return spline.Shape()
def process_shape(shape):
'''extracts edges from a shape'''
edges = []
edge_explorer = TopExp_Explorer(shape, TopAbs.TopAbs_EDGE)
while edge_explorer.More():
edge = TopoDS().Edge(edge_explorer.Current())
cons = BRepAdaptor_Curve()
cons.Initialize(edge)
crv_type = cons.GetType()
if crv_type == GeomAbs.GeomAbs_Circle:
c = cons.Circle()
h = Handle_Geom_Circle(Geom_Circle(c))
h = GeomConvert().CurveToBSplineCurve(h)
sign = 1.0
elif crv_type == GeomAbs.GeomAbs_BSplineCurve:
c = cons.BSpline()
h = Handle_Geom_BSplineCurve(c)
sign = -1.0
else:
pass
crv = h.GetObject()
props = GeomLProp_CLProps(crv.GetHandle(),
1, # What does this Integer control?!
Precision().Confusion())
for u in NP.arange(cons.FirstParameter(),
cons.LastParameter()+0.001,
(cons.LastParameter() -
cons.FirstParameter())/100.0):
props.SetParameter(u)
d1 = gp.gp_Dir()
props.Tangent(d1) # d is now the tangent vector
z = gp.gp_Dir(0.0,0.0,1.0) # Curve is in a plane and
props.Normal does not seem to work
d3 = d1.Crossed(z)
print('%f,%f,%f,%f' %(u, d3.X(), d3.Y(), d3.Z()))
origin = props.Value()
array = []
array.append(gp.gp_Pnt(origin.X(), origin.Y(), origin.Z()))
array.append(gp.gp_Pnt(origin.X()+sign*400.0*d3.X(),
origin.Y()+sign*400.0*d3.Y(),
origin.Z()+sign*400.0*d3.Z()))
xxx = point2d_list_to_TColgp_Array1OfPnt(array)
SPL1 = GeomAPI_PointsToBSpline(xxx).Curve()
edges.append(make_edge(SPL1))
edge_explorer.Next()
return edges
display, start_display, add_menu, add_function_to_menu = init_display()
my_step_importer = STEPImporter(r"simple.STEP")
my_step_importer.ReadFile()
print "Number of shapes:%i"%my_step_importer.GetNbrShapes()
the_shapes = my_step_importer.GetShapes()
display.DisplayShape(the_shapes)
normals = []
for shape in the_shapes:
normals.extend(process_shape(shape))
display.DisplayColoredShape(normals, 'GREEN')
start_display()
On Thu, Jan 21, 2010 at 11:26 PM, Thomas Paviot <[email protected]> wrote:
> 2010/1/21 Bryan Bishop <[email protected]>
>
> On Thu, Jan 21, 2010 at 10:47 AM, Charles McCreary
>> <[email protected]> wrote:
>> > Now I want to extract some information from the imported geometry. The
>> > geometry consists of 3 b-spline curves with knots. I've perused the
>> doxygen
>> > generated documents but I'm still rather lost on how to begin. I'm
>> unclear
>> > on how to even start a simple task like extracting the points from the
>> > spline. Suggestions?
>>
>> Holy crap, a PE :-). Welcome aboard Charles. Let's see if this does the
>> trick:
>>
>> def process_shape(shape):
>> '''extracts faces from a shape
>> note: if this doesnt work you should try process_face(shape)
>> returns a list of faces'''
>> faces = []
>> explorer = TopExp_Explorer(shape, TopAbs_FACE)
>> while explorer.More():
>> face = TopoDS().Face(explorer.Current())
>> faces.append(face)
>> explorer.Next()
>> return faces
>>
>> def process_face(face):
>> '''traverses a face for wires
>> returns a list of wires'''
>> wires = []
>> explorer = TopExp_Explorer(face, TopAbs_EDGE)
>> while explorer.More():
>> edge = TopoDS().Edge(explorer.Current())
>> wire = BRepBuilderAPI_MakeWire(edge).Wire()
>> wires.append(wire)
>> explorer.Next()
>> return wires
>>
>> At least, this might get you a good head start: check out the
>> TopExp_Explorer class for sure. Another good technique is to use
>> bpython-interpreter.org, which can really help figure out pythonOCC's
>> deep internals without too much pain. Also, some of us pythonOCC users
>> are in #hplusroadmap on irc.freenode.net if you would like real-time
>> support over IRC.
>>
>> - Bryan
>> http://heybryan.org/
>> 1 512 203 0507
>>
>>
> Hi Bryan,
>
> You should definitely not use directly the TopExp_Explorer builtin OCC
> class but rather the Topology.py high level module. This implementation adds
> hash check of objects returned by TopExp_Explorer iterator to ensure that an
> element (either a vertex, wire etc.) matching the criterion (TopABS_VERTEX,
> TopAbs_WIRE etc.) is unique in the returned list.
>
> Regards,
>
> Thomas
>
>
> _______________________________________________
> Pythonocc-users mailing list
> [email protected]
> https://mail.gna.org/listinfo/pythonocc-users
>
>
--
Charles McCreary P.E.
CRM Engineering
903.643.3490 - office
903.224.5701 - mobile/GV
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