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Version 5 (modified by skulovec, 13 years ago) (diff)
izdelava prizme + mirror

PythonOCC omogoča enostavnejšo uporabo jedra modelirnika OpenCascade v jeziku Python. Prednost Pythona v primerjavi z C++ je:

Prenosljivosti. Programi se interpretirajo in jih ni potrebno prevajati zato delujejo na vseh operacijskih sistemih. So pa nekoliko pošasnejši.
Enostavnejša namestitev potrebnih knjižnic, brez zahtevne konfiguracije povezovalnih parametrov, ki so značilni za C++.
Lažje učenje jezika. V interaktivnem načinu obstaja tudi refleksija oziroma dinamično prepoznavanje možnih ukazov v objektu.

Za vaje je potrebno na Windowsih (tudi 63 bitnih) namestiti naslednje pakete:

Python 2.6 interpreter jezika z osnovnimi knjižnicami
wxPython za opravljanje z okni
PythonOCC povezava Pytona z jedrom OpenCascade

Neobvezno vendar priporočljivo je namesti še:

iPython za interektivno delo
NumPy za delo z numeričnimi metodami in matrikami.
SciPy za delo z znanstvenimi algoritmi.

Pred preizkusom prvih primerov je potrebno nastaviti še pot do interpreterja v Moj računalnik -> Lastnosti -> Dodatne nastavitve sistema -> Spremenljivke okolja ... -> Sistemske spremenljivke -> Path -> Uredi -> Vrednost spremeljivke: in na koncu dodamo ;c:\Python26;. Po tem je potremn računalnik vnovič zagnati.

V primeru, da nam klik na Start->Vsi programi->pythonOCC -> Examples -> Level1 -> HelloWorld -> helloworld.py okno na hitro odpre, vendar modela ne prikaže, imamo težave z OpenGL krmilniki. Najenostavneje težavo odpravimo s spremembo osnovnega prikazovalnika v datoteki C:\Python26\Lib\site-packages\OCC\Display\wxDisplay.py v kateri platformo darwin poistovetimo z win32 tako da del kode v tej datoteki izgleda:

if sys.platform=='win32':
    BaseClass = wx.Panel
else:
    import wx.glcanvas
    BaseClass = wx.glcanvas.GLCanvas

Predstavitev CAD-jedra Open CASCADE na primerih

Pregled uporabljenih OCC knjižnic

## Importanje različnih knjižnic

# Uporabniški vmesnik GUI
from OCC.Display.SimpleGui import *

# Matematična knjižnica
import math

# OpenCascade
from OCC.gp import * #točke
from OCC.BRepBuilderAPI import * #gradimo robove, segmente, mreže ...
from OCC.BRepPrimAPI import * #izdelava osnovnih geometrijskih primitivov
from OCC.BRepFilletAPI import * #izdelava zaokrožitev

Točnejša navodila, opis funkcij in knjižnic lahko dobimo v PythonOCC dokumentaciji.

Inicializacija zaslona in izdelava grafičnega vmesnika

# OCC.Display.SimpleGui.init_display() returns multiple
# values which are assigned here
display, start_display, add_menu, add_function_to_menu = \
init_display()
draw_bottle() #kličemo CAD model, ki ga želimo prikazati na zaslonu
start_display()

Risanje točk v prostoru

Izdelava točk v prostoru je najosnovnejša operacija v OCC.

# Definiranje začetnih točk
aPnt1 = gp_Pnt(-myWidth / 2. , 0 , 0)
aPnt2 = gp_Pnt(-myWidth / 2. , -myThickness / 4. , 0)
aPnt3 = gp_Pnt(0 , -myThickness / 2. , 0)
aPnt4 = gp_Pnt(myWidth / 2. , -myThickness / 4. , 0)
aPnt5 = gp_Pnt(myWidth / 2. , 0 , 0)

Izdelava robnih elementov

V naslednjem koraku se iz začetnih točk izdela robove:

# Definiranje geometrije
aArcOfCircle = GC_MakeArcOfCircle(aPnt2,aPnt3 ,aPnt4)
aSegment1 = GC_MakeSegment(aPnt1 , aPnt2)
aSegment2 = GC_MakeSegment(aPnt4 , aPnt5)

# Definiranje topologije
aEdge1 = BRepBuilderAPI_MakeEdge(aSegment1.Value())
aEdge2 = BRepBuilderAPI_MakeEdge(aArcOfCircle.Value())
aEdge3 = BRepBuilderAPI_MakeEdge(aSegment2.Value())

Povezovanje robnih elementov v mreže

Robne elemente se v nadaljevanju združi v mrežo.

# Izdelava mreže
aWire  = BRepBuilderAPI_MakeWire(aEdge1.Edge() , aEdge2.Edge() ,aEdge3.Edge())

Uporaba funkcij za izdelavo objektov v prostoru

# Izdelava celotnega profila - mirror
xAxis = gp_OX()
aTrsf = gp_Trsf()
aTrsf.SetMirror(xAxis)
aBRepTrsf = BRepBuilderAPI_Transform(aWire.Shape() , aTrsf)
aMirroredShape = aBRepTrsf.Shape()
aMirroredWire = TopoDS_wire(aMirroredShape)
mkWire = BRepBuilderAPI_MakeWire()
mkWire.Add(aWire.Wire())
mkWire.Add(aMirroredWire)
myWireProfile = mkWire.Wire()

# Telo: Iz profila se izdela telo (Funkcija izvleka 3D)
myFaceProfile = BRepBuilderAPI_MakeFace(myWireProfile)
aPrismVec = gp_Vec(0 , 0 , myHeight)
myBody = BRepPrimAPI_MakePrism(myFaceProfile.Face() , aPrismVec)

Risanje geometrijskih primitivov

V OCC že obstajajo funkcije za izdelavo geometrijskih primitivov (kocka, valj,...), kar je prikazano na spodnjem primeru.

from OCC.Display.SimpleGui import *
from OCC.BRepPrimAPI import *

display, start_display, add_menu, add_function_to_menu = init_display()
my_box = BRepPrimAPI_MakeBox(10.,20.,30.).Shape()
# ali my_cylinder = BRepPrimAPI_MakeCylinder(neckAx2 , myNeckRadius , myNeckHeight), kjer so spremenljivke že preddefinirane 

display.DisplayShape(my_box) # ali display.DisplayShape(my_cylinder)
start_display()

Izdelava primera Bottle z uporabo programskega jezika Python in knjižnice OCC

Naslednji primer prikazuje izdelavo primera BottleCAD. Podrobnejši razdelek posameznih delov programske kode dobimo na MakeBottleCAD(C++).

##Copyright 2011 Simon Kulovec (simon.kulovec@lecad.si)
##Example: MakeCADBottle
##This file is part of pythonOCC.

## Importanje različnih knjižnic

# Uporabniški vmesnik GUI
from OCC.Display.SimpleGui import *

# OpenCascade
from OCC.gp import *
from OCC.TopoDS import *
from OCC.GC import *
from OCC.BRepBuilderAPI import *
from OCC.BRepPrimAPI import *
from OCC.BRepFilletAPI import *
from OCC.BRepAlgoAPI import *
from OCC.Utils.Topology import *
from OCC.Geom import *
from OCC.Geom2d import *
from OCC.GCE2d import *
from OCC.BRep import *
from OCC.BRepLib import *
from OCC.BRepOffsetAPI import *
from OCC.TopTools import *
from OCC.TopAbs import *
from OCC.TopExp import *

import math

def show_bottle(aRes):
    display.EraseAll()
    print dir(display)
    display.DisplayShape(aRes)

def define_points(myWidth, myThickness, myHeight):
    #Definiranje začetnih točk
    aPnt1 = gp_Pnt(-myWidth / 2. , 0 , 0)
    aPnt2 = gp_Pnt(-myWidth / 2. , -myThickness / 4. , 0)
    aPnt3 = gp_Pnt(0 , -myThickness / 2. , 0)
    aPnt4 = gp_Pnt(myWidth / 2. , -myThickness / 4. , 0)
    aPnt5 = gp_Pnt(myWidth / 2. , 0 , 0)

    #Definiranje geometrije
    aArcOfCircle = GC_MakeArcOfCircle(aPnt2,aPnt3 ,aPnt4)
    aSegment1 = GC_MakeSegment(aPnt1 , aPnt2)
    aSegment2 = GC_MakeSegment(aPnt4 , aPnt5)

    #Definiranje topologije
    aEdge1 = BRepBuilderAPI_MakeEdge(aSegment1.Value())
    aEdge2 = BRepBuilderAPI_MakeEdge(aArcOfCircle.Value())
    aEdge3 = BRepBuilderAPI_MakeEdge(aSegment2.Value())
    aWire  = BRepBuilderAPI_MakeWire(aEdge1.Edge() , aEdge2.Edge() ,aEdge3.Edge())

    #Izdelava celotnega profila - mirror
    xAxis = gp_OX()
    aTrsf = gp_Trsf()
    aTrsf.SetMirror(xAxis)
    aBRepTrsf = BRepBuilderAPI_Transform(aWire.Shape() , aTrsf)
    aMirroredShape = aBRepTrsf.Shape()
    aMirroredWire = TopoDS_wire(aMirroredShape)
    mkWire = BRepBuilderAPI_MakeWire()
    mkWire.Add(aWire.Wire())
    mkWire.Add(aMirroredWire)
    myWireProfile = mkWire.Wire()

    # Telo: Iz profila se izdela telo
    myFaceProfile = BRepBuilderAPI_MakeFace(myWireProfile)
    aPrismVec = gp_Vec(0 , 0 , myHeight)
    myBody = BRepPrimAPI_MakePrism(myFaceProfile.Face() , aPrismVec)

    # Telo: Dodamo zaokrožitve (fillet)
    mkFillet = BRepFilletAPI_MakeFillet(myBody.Shape())
    topology_traverser = Topo(myBody.Shape())
    for aEdge in topology_traverser.edges():
        mkFillet.Add(myThickness / 12. , aEdge)
    myBody = mkFillet.Shape()

    #Dodajanje grla na steklenico
    neckLocation = gp_Pnt(0, 0, myHeight)
    neckNormal = gp_DZ()
    neckAx2 = gp_Ax2(neckLocation, neckNormal)

    myNeckRadius = myThickness / 4
    myNeckHeight = myHeight / 10

    mkCylinder = BRepPrimAPI_MakeCylinder(neckAx2 , myNeckRadius , \
                                          myNeckHeight)
    myNeck = mkCylinder.Shape();

    myBody = BRepAlgoAPI_Fuse(myBody, myNeck)

    # Izdelava votle steklenice
    faceToRemove = None
    zMax = -1;
    t = Topo(myBody.Shape())
    k=1
    for  aFace in t.faces():
    
        aSurface = BRep_Tool().Surface(aFace)
    
        if aSurface.GetObject().IsInstance('Geom_Plane'):
            aPlane = Handle_Geom_Plane().DownCast(aSurface).GetObject()
            aPnt = aPlane.Location()
            aZ = aPnt.Z()
            if aZ>zMax:
                faceToRemove = aFace

    facesToRemove = TopTools_ListOfShape()
    facesToRemove.Append(faceToRemove)
    myBody = BRepOffsetAPI_MakeThickSolid(myBody.Shape() , facesToRemove , \
                                          -myThickness/50 , 1.e-3)
    
    # Threading : Create Surfaces
    aCyl1 = Geom_CylindricalSurface(gp_Ax3(neckAx2) , myNeckRadius * 0.99)
    aCyl2 = Geom_CylindricalSurface(gp_Ax3(neckAx2) , myNeckRadius * 1.05)

    # Threading : Define 2D Curves
    aPnt = gp_Pnt2d(2. * 3.141592 , myNeckHeight / 2.)
    aDir = gp_Dir2d(2. * 3.141592 , myNeckHeight / 4.)
    aAx2d = gp_Ax2d(aPnt , aDir)
        
    aMajor = 2. * 3.141592
    aMinor = myNeckHeight / 10.
    
    anEllipse1 = Geom2d_Ellipse(aAx2d , aMajor , aMinor)
    anEllipse2 = Geom2d_Ellipse(aAx2d , aMajor , aMinor / 4)

    aArc2 = Geom2d_TrimmedCurve(anEllipse1.GetHandle() , 3.141592, 0.)
    aArc1 = Geom2d_TrimmedCurve(anEllipse2.GetHandle() , 3.141592, 0.)

    anEllipsePnt2 = anEllipse1.Value(0.)
    anEllipsePnt1 = anEllipse1.Value(3.141592)
    
    aSegment = GCE2d_MakeSegment(anEllipsePnt1 , anEllipsePnt2)

    # Threading : Build Edges and Wires
    aEdge1OnSurf1 = BRepBuilderAPI_MakeEdge(aArc1.GetHandle() , aCyl1.GetHandle())
    aEdge2OnSurf1 = BRepBuilderAPI_MakeEdge(aSegment.Value() , aCyl1.GetHandle())
    aEdge1OnSurf2 = BRepBuilderAPI_MakeEdge(aArc2.GetHandle() , aCyl2.GetHandle())
    aEdge2OnSurf2 = BRepBuilderAPI_MakeEdge(aSegment.Value() , aCyl2.GetHandle())
    print dir(aEdge1OnSurf1)
    threadingWire1 = BRepBuilderAPI_MakeWire(aEdge1OnSurf1.Edge() , aEdge2OnSurf1.Edge())
    threadingWire2 = BRepBuilderAPI_MakeWire(aEdge1OnSurf2.Edge() , aEdge2OnSurf2.Edge())


    BRepLib().BuildCurves3d(threadingWire1.Wire())
    BRepLib().BuildCurves3d(threadingWire2.Wire())

    # Create Threading
    aTool = BRepOffsetAPI_ThruSections(True)

    aTool.AddWire(threadingWire1.Wire())
    aTool.AddWire(threadingWire2.Wire())
    aTool.CheckCompatibility(False)

    myThreading = aTool.Shape()

    # Izdelava sestava
    aRes = TopoDS_Compound()

    aBuilder = BRep_Builder()
    aBuilder.MakeCompound (aRes)

    aBuilder.Add (aRes, myBody.Shape())
    aBuilder.Add (aRes, myThreading)

    # Izris oblike
    show_bottle(aPnt1)

def draw_bottle(event=None):
    # Definiranje razdalj: širina, dolžina, višina
    myWidth = 50.0
    myThickness = 30.0
    myHeight = 70.0
    # Define Points
    define_points(myWidth, myThickness, myHeight)
    
if __name__ == '__main__':
    # OCC.Display.SimpleGui.init_display() returns multiple
    # values which are assigned here
    display, start_display, add_menu, add_function_to_menu = \
    init_display()
    draw_bottle() #kličemo podprogram za izris bottle
    start_display()

Izris CAD kocke

## Izdelava kocke

from OCC.Display.SimpleGui import *
from OCC.BRepPrimAPI import *
from OCC.gp import *
from OCC.GC import *
from OCC.BRepBuilderAPI import *
#from OCC.TopoDS import *

display, start_display, add_menu, add_function_to_menu = init_display()

#Definiranje točk v prostoru
aPnt1 = gp_Pnt(0 , 0 , 0)
aPnt2 = gp_Pnt(10 , 0, 0)
aPnt3 = gp_Pnt(10 , 10 , 0)
aPnt4 = gp_Pnt(0, 10 , 0)

#Izdelava segmentov--definiranje geometrije
aSegment1 = GC_MakeSegment(aPnt1 , aPnt2)
aSegment2 = GC_MakeSegment(aPnt2 , aPnt3)
aSegment3 = GC_MakeSegment(aPnt3 , aPnt4)
aSegment4 = GC_MakeSegment(aPnt4 , aPnt1)

#Izdelava robov -- definiranje topologije
aEdge1 = BRepBuilderAPI_MakeEdge(aSegment1.Value())
aEdge2 = BRepBuilderAPI_MakeEdge(aSegment2.Value())
aEdge3 = BRepBuilderAPI_MakeEdge(aSegment3.Value())
aEdge4 = BRepBuilderAPI_MakeEdge(aSegment4.Value())

#Povezovanje robov v mrežo
aWire  = BRepBuilderAPI_MakeWire(aEdge1.Edge() , aEdge2.Edge() ,\
                                 aEdge3.Edge(), aEdge4.Edge())

#Telo: Iz profila se izdela telo
myFaceProfile = BRepBuilderAPI_MakeFace(aWire.Wire())

aPrismVec = gp_Vec(0 , 0 , 10)

myBody = BRepPrimAPI_MakePrism(myFaceProfile.Face() , aPrismVec).Shape()

display.DisplayShape(myBody)
start_display()

Izris CAD prizme

## Izdelava prizme --primer bottle

from OCC.Display.SimpleGui import *
from OCC.BRepPrimAPI import *
from OCC.gp import *
from OCC.GC import *
from OCC.BRepBuilderAPI import *
from OCC.TopoDS import *

display, start_display, add_menu, add_function_to_menu = init_display()

myWidth = 50.0
myThickness = 30.0
myHeight = 70.0

#Definiranje začetnih točk
aPnt1 = gp_Pnt(-myWidth / 2. , 0 , 0)
aPnt2 = gp_Pnt(-myWidth / 2. , -myThickness / 4. , 0)
aPnt3 = gp_Pnt(0 , -myThickness / 2. , 0)
aPnt4 = gp_Pnt(myWidth / 2. , -myThickness / 4. , 0)
aPnt5 = gp_Pnt(myWidth / 2. , 0 , 0)

#Izdelava segmentov--definiranje geometrije
aArcOfCircle = GC_MakeArcOfCircle(aPnt2,aPnt3 ,aPnt4)
aSegment1 = GC_MakeSegment(aPnt1 , aPnt2)
aSegment2 = GC_MakeSegment(aPnt4 , aPnt5)

#Izdelava robov -- definiranje topologije
aEdge1 = BRepBuilderAPI_MakeEdge(aSegment1.Value())
aEdge2 = BRepBuilderAPI_MakeEdge(aArcOfCircle.Value())
aEdge3 = BRepBuilderAPI_MakeEdge(aSegment2.Value())

#Povezovanje robov v mrežo
aWire  = BRepBuilderAPI_MakeWire(aEdge1.Edge() , aEdge2.Edge() ,\
                                 aEdge3.Edge())

#Izdelava celotnega profila - mirror
xAxis = gp_OX()
aTrsf = gp_Trsf()
aTrsf.SetMirror(xAxis)
aBRepTrsf = BRepBuilderAPI_Transform(aWire.Shape() , aTrsf)
aMirroredShape = aBRepTrsf.Shape()
aMirroredWire = TopoDS_wire(aMirroredShape)
mkWire = BRepBuilderAPI_MakeWire()
mkWire.Add(aWire.Wire())
mkWire.Add(aMirroredWire)
myWireProfile = mkWire.Wire()

#Telo: Iz profila se izdela telo
myFaceProfile = BRepBuilderAPI_MakeFace(myWireProfile)
aPrismVec = gp_Vec(0 , 0 , myHeight)
myBody = BRepPrimAPI_MakePrism(myFaceProfile.Face() , aPrismVec).Shape()

display.DisplayShape(myBody)
start_display()

Attachments (11)

boolove-operacije.svg (23.4 KB) - added by Leon Kos 12 years ago. Boolove operacije
points-solid.svg (49.9 KB) - added by skulovec 12 years ago. Dodajanje slike za izdelavo solid iz točk
3Dprimitives.png (16.0 KB) - added by skulovec 12 years ago. 3Dprimitives
VisualizationOfGeometryWithUtilisingpythonOCC.pdf (1.3 MB) - added by skulovec 12 years ago. Vizualizacija s PythonOCC
modalg.pdf (728.6 KB) - added by Leon Kos 11 years ago. Modelling algorithms za OpenCASCADE 6.6
modata.pdf (573.0 KB) - added by Leon Kos 11 years ago. Modeling Data
qtDisplay.py (9.9 KB) - added by mprotic 9 years ago.
bottle.png (68.3 KB) - added by dpenko 9 years ago. "bottle" primer - slikovni prikaz
edge_primer.PNG (19.9 KB) - added by mtelenta 8 years ago.
prerezana_piramida.PNG (26.8 KB) - added by mtelenta 8 years ago.
torus_webgl.PNG (348.8 KB) - added by mtelenta 8 years ago.

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