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: 1. [http://python.org/ftp/python/2.6.6/python-2.6.6.msi Python 2.6] interpreter jezika z osnovnimi knjižnicami 2. [http://downloads.sourceforge.net/wxpython/wxPython2.8-win32-unicode-2.8.12.1-py26.exe wxPython] za opravljanje z okni 3. [http://pythonocc.googlecode.com/files/pythonOCC-0.5-win32-all-in-one-py26.exe PythonOCC] povezava Pytona z jedrom OpenCascade Neobvezno vendar priporočljivo je namesti še: 1. [http://archive.ipython.org/release/0.11/ipython-0.11.win32-setup.exe iPython] za interektivno delo 2. [http://downloads.sourceforge.net/project/numpy/NumPy/1.6.1/numpy-1.6.1-win32-superpack-python2.6.exe NumPy] za delo z numeričnimi metodami in matrikami. 3. [http://downloads.sourceforge.net/project/scipy/scipy/0.10.0b2/scipy-0.10.0b2-win32-superpack-python2.6.exe 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: {{{ #!python 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 === {{{ #!python ## 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=== {{{ #!python # 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. {{{ #!python # 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: {{{ #!python # 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. {{{ #!python # Izdelava mreže aWire = BRepBuilderAPI_MakeWire(aEdge1.Edge() , aEdge2.Edge() ,aEdge3.Edge()) }}} === Uporaba funkcij za izdelavo objektov v prostoru === {{{ #!python # 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. {{{ #!python 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 [[http://trac.lecad.si/vaje/wiki/OpenCascade|MakeBottleCAD(C++)]]. {{{ #!python ##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 === {{{ #!python ## 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 === {{{ #!python ## 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() }}}