This is cross-posted to the OpenCascade forum (
http://www.opencascade.org/org/forum/thread_18806/):
The attached python script demonstrates a particularly difficult problem I'm
trying to solve. I've tried this in SolidWorks 2009 x64 and it *eventually*
creates the geometry but crashes while attempting to save as a STEP or STL
file. I'm looking for recommendations on how I can speed up the process. The
transverse cuts are completed rather quickly since the only intersections
are with the rectangular block. The longitudinal cuts take about 20 minutes
each and there are 108! The longitudinal cuts cut through each of the 283
transverse cuts as well as the rectangular blocks.
--
Charles McCreary P.E.
CRM Engineering
903.643.3490 - office
903.224.5701 - mobile/GV
from OCC.Display.SimpleGui import *
from OCC.BRepPrimAPI import *
import OCC.gp
import OCC.GC
import OCC.BRepBuilderAPI
import OCC.Geom
import OCC.BRepPrimAPI
import OCC.BRepAlgoAPI
import OCC.Utils.DataExchange.STEP
import OCC.Utils.DataExchange.STL
import numpy as NP
import math
length = 594.6
width = 136.0
thickness = 5.0
spacing = 2.1
groove_width = 0.175
groove_depth = 0.03
display, start_display, add_menu, add_function_to_menu = init_display()
lga = BRepPrimAPI_MakeBox(length,width,thickness).Shape()
# Make the transverse grooves
num_transverse = len(NP.arange(2.1,594.6,2.1))
for i, x in enumerate(NP.arange(2.1,594.6,2.1)):
print('Working on transverse groove %d of %d' % (i, num_transverse))
pnt1 = OCC.gp.gp_Pnt(x, 0., thickness - groove_depth)
pnt2 = OCC.gp.gp_Pnt(x + groove_width/2.0, 0., thickness)
pnt3 = OCC.gp.gp_Pnt(x - groove_width/2.0, 0., thickness)
seg1 = OCC.GC.GC_MakeSegment(pnt1, pnt2)
seg2 = OCC.GC.GC_MakeSegment(pnt2, pnt3)
seg3 = OCC.GC.GC_MakeSegment(pnt3, pnt1)
e1 = OCC.BRepBuilderAPI.BRepBuilderAPI_MakeEdge(OCC.Geom.Handle_Geom_TrimmedCurve(seg1.Value()))
e2 = OCC.BRepBuilderAPI.BRepBuilderAPI_MakeEdge(OCC.Geom.Handle_Geom_TrimmedCurve(seg2.Value()))
e3 = OCC.BRepBuilderAPI.BRepBuilderAPI_MakeEdge(OCC.Geom.Handle_Geom_TrimmedCurve(seg3.Value()))
mw = OCC.BRepBuilderAPI.BRepBuilderAPI_MakeWire()
mw.Add(e1.Edge())
mw.Add(e2.Edge())
mw.Add(e3.Edge())
face = OCC.BRepBuilderAPI.BRepBuilderAPI_MakeFace(mw.Wire())
v = OCC.gp.gp_Vec(0., width, 0.)
b = OCC.BRepPrimAPI.BRepPrimAPI_MakePrism(face.Face() , v)
lga = OCC.BRepAlgoAPI.BRepAlgoAPI_Cut(lga, b.Shape()).Shape()
# Make the grooves with an arithmetic progression
a1 = 1.32 # Spacing between first two grooves
an = 0.85 # Spacing between next to the last and the last groove
d1 = 9.0 # Distance from the edge to the center of the first groove
d2 = 9.0 # Distance from the edge to the center of the last groove
sn = width - d1 - d2 # Distance from first groove to last groove
n = int(math.floor(2*sn/(a1+an))) # number of grooves
d = (an-a1)/(n-1) # difference in spacing between grooves
y = d1
for i, k in enumerate(range(1,n+1)):
print('Working on longitudinal groove %d of %d' % (i,n))
pnt1 = OCC.gp.gp_Pnt(0.0, y, thickness - groove_depth)
pnt2 = OCC.gp.gp_Pnt(0.0, y + groove_width/2.0, thickness)
pnt3 = OCC.gp.gp_Pnt(0.0, y - groove_width/2.0, thickness)
seg1 = OCC.GC.GC_MakeSegment(pnt1, pnt2)
seg2 = OCC.GC.GC_MakeSegment(pnt2, pnt3)
seg3 = OCC.GC.GC_MakeSegment(pnt3, pnt1)
e1 = OCC.BRepBuilderAPI.BRepBuilderAPI_MakeEdge(OCC.Geom.Handle_Geom_TrimmedCurve(seg1.Value()))
e2 = OCC.BRepBuilderAPI.BRepBuilderAPI_MakeEdge(OCC.Geom.Handle_Geom_TrimmedCurve(seg2.Value()))
e3 = OCC.BRepBuilderAPI.BRepBuilderAPI_MakeEdge(OCC.Geom.Handle_Geom_TrimmedCurve(seg3.Value()))
mw = OCC.BRepBuilderAPI.BRepBuilderAPI_MakeWire()
mw.Add(e1.Edge())
mw.Add(e2.Edge())
mw.Add(e3.Edge())
face = OCC.BRepBuilderAPI.BRepBuilderAPI_MakeFace(mw.Wire())
v = OCC.gp.gp_Vec(length, 0., 0.)
b = OCC.BRepPrimAPI.BRepPrimAPI_MakePrism(face.Face() , v)
lga = OCC.BRepAlgoAPI.BRepAlgoAPI_Cut(lga, b.Shape()).Shape()
ak = a1 + (k-1)*d
y = y + ak
display.DisplayShape(lga)
start_display()
stp_exporter = OCC.Utils.DataExchange.STEP.STEPExporter('lga.stp', verbose=True)
stp_exporter.SetTolerance(tolerance=0.00001)
stp_exporter.AddShape(lga)
stp_exporter.WriteFile()
stl_exporter = OCC.Utils.DataExchange.STL.STLExporter(filename='lga.stl')
stp_exporter.SetShape(lga)
stp_exporter.WriteFile()
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