Changes between Initial Version and Version 1 of occt

Timestamp:

Nov 19, 2018, 11:40:35 AM (7 years ago)

Author:

Leon Kos

Comment:

Prvi draft za predstavitev PyOCCT

occt

@@ +1 @@
+== Uporaba modula PythonOCCT ==
+
+Projekt **PythonOCCT** je še ena priredba knjižnice OpenCASCADE 7.2.0 za programiranje v jeziku Python.
+Od PythonOCC-ja se razlikuje v verziji OpenCASCADE in v klicanju metod. 
+
+Statične funkcije se v **PythonOCC** uvozijo kar na modularnem nivoju:
+
+{{{#!python
+from OCC.TodoDS import topods_Edge
+}}}
+
+Med tem ko v PythonOCCT so statične funkcije znotraj razredov in imajo na koncu še podčrtaj
+
+{{{#!python
+from OCCT.TopoDS import TopoDS
+edge = TopoDS.Edge_(shape)
+}}}
+
+Prav tako se v PythonOCCT ne uporablja več metod **GetHandle**, **Downcast** in **GetObject**, ker se že v kodi PythonOCCT vse avtomatsko to naredi:
+
+V **PythonOCC**
+{{{#!python
+handle_geom = line.Copy()
+new_line = Handle_Geom_Line.Downcast(handle_geom).GetObject()
+}}}
+
+V **PythonOCCT**
+{{{#!python
+new_line = line.Copy()
+}}}
+
+To naredi stvari precej pitonične, saj lahko direktno ugotovimo tip geometrije z uporabo python metode **isinstance**:
+
+{{{#!python
+# S pomočjo PythonOCC-ja preverimo če je TopoDS_Shape Geom_Plane.
+hs = BRep_Tool_Surface(face)
+downcast_result = Geom_Plane.DownCast(hs)
+# Če je downcast_result tipa None, spremenljivka face ni Geom_Plane.
+if downcast_result is None:
+    return False
+else:
+    return True
+}}}
+
+
+{{{#!python
+# S pomočjo PythonOCCT-ja preverimo če je TopoDS_Shape Geom_Plane.
+hs = BRep_Tool_Surface(face)
+if isinstance(hs, Geom_Plane):
+    return True
+else:
+    return False
+}}}
+
+=== Izdelava primera Bottle z uporabo programskega jezika Python in knjižnice OCCT ===
+Naslednji primer prikazuje izdelavo primera BottleCAD. Podrobnejši razdelek posameznih delov programske kode dobimo na [[http://trac.lecad.si/vaje/wiki/OpenCascade|MakeBottleCAD(C++)]]. Za vizualizacijo se uporablja SALOME-8.5.0
+
+[[Image(bottle.png, width=480px, right)]]
+{{{
+#!python
+##Uredil in posodobil 2018 Gregor Simič (gregor.simic@lecad.fs.uni-lj.si)
+import math
+
+# from OCCT.gp import gp_Pnt, gp_OX, gp_Vec, gp_Trsf, gp_DZ, gp_Ax2, gp_Ax3, gp_Pnt2d, gp_Dir2d, gp_Ax2d
+from OCCT.gp import gp_Pnt, gp, gp_Vec, gp_Trsf, gp_Ax2, gp_Ax3, gp_Pnt2d, gp_Dir2d, gp_Ax2d
+# Classes gp_OX, gp_DZ are statical methods and in OCCT stored inside
+# OCCT.gp.gp as OX_ and DZ_ respectively.
+
+from OCCT.GC import GC_MakeArcOfCircle, GC_MakeSegment
+from OCCT.GCE2d import GCE2d_MakeSegment
+from OCCT.Geom import Geom_Plane, Geom_CylindricalSurface, Geom_Surface
+from OCCT.Geom2d import Geom2d_Ellipse, Geom2d_TrimmedCurve, Geom2d_Ellipse, Geom2d_Curve
+from OCCT.BRepBuilderAPI import BRepBuilderAPI_MakeEdge, BRepBuilderAPI_MakeWire, BRepBuilderAPI_MakeFace, \
+    BRepBuilderAPI_Transform
+from OCCT.BRepPrimAPI import BRepPrimAPI_MakePrism, BRepPrimAPI_MakeCylinder
+from OCCT.BRepFilletAPI import BRepFilletAPI_MakeFillet
+from OCCT.BRepAlgoAPI import BRepAlgoAPI_Fuse
+from OCCT.BRepOffsetAPI import BRepOffsetAPI_MakeThickSolid, BRepOffsetAPI_ThruSections
+
+# from OCC.Core.BRepLib import breplib
+# In OCCT the modules preserve the case.
+from OCCT.BRepLib import BRepLib
+
+# from OCC.Core.BRep import BRep_Tool_Surface, BRep_Builder
+from OCCT.BRep import BRep_Tool, BRep_Builder
+# OCCT does not have OCCT.Core but rather all modules are accessed directly
+# from OCCT. Again BRep_Tool_Surface from OCC is a static method to create
+# a Surface, hence in OCCT it is called from BRep_Tools as Surface_
+
+from OCCT.TopoDS import TopoDS, TopoDS_Edge, TopoDS_Compound
+from OCCT.TopExp import TopExp_Explorer
+from OCCT.TopAbs import TopAbs_EDGE, TopAbs_FACE
+from OCCT.TopTools import TopTools_ListOfShape
+
+def face_is_plane(face):
+    """
+    Returns True if the TopoDS_Shape is a Geom_Plane, False otherwise.
+    """
+    hs = BRep_Tool.Surface_(face)
+    # downcast_result = Geom_Plane.DownCast(hs)
+    # OCCT 7.2.0 does not have the DownCast function anymore, in this case
+    # we use we simply use the isinstance method to check if the shape
+    # is a Geom_Plane.
+    if isinstance(hs, Geom_Plane):
+        return True
+    else:
+        # Othe cases when it returns false are, Geom_CylindricalSurface,
+        # Geom_ToroidalSurface, Geom_SphericalSurface
+        return False
+
+
+def geom_plane_from_face(aFace):
+    """
+    Returns the geometric plane entity from a planar surface
+    """
+    # return Geom_Plane.DownCast(BRep_Tool.Surface_(aFace))
+    return BRep_Tool.Surface_(aFace).Pln()
+
+
+height = 70
+width = 50
+thickness = 30
+
+print("creating bottle")
+# The points we'll use to create the profile of the bottle's body
+aPnt1 = gp_Pnt(-width / 2.0, 0, 0)
+aPnt2 = gp_Pnt(-width / 2.0, -thickness / 4.0, 0)
+aPnt3 = gp_Pnt(0, -thickness / 2.0, 0)
+aPnt4 = gp_Pnt(width / 2.0, -thickness / 4.0, 0)
+aPnt5 = gp_Pnt(width / 2.0, 0, 0)
+
+aArcOfCircle = GC_MakeArcOfCircle(aPnt2, aPnt3, aPnt4)
+aSegment1 = GC_MakeSegment(aPnt1, aPnt2)
+aSegment2 = GC_MakeSegment(aPnt4, aPnt5)
+
+# Could also construct the line edges directly using the points instead of the resulting line
+aEdge1 = BRepBuilderAPI_MakeEdge(aSegment1.Value())
+aEdge2 = BRepBuilderAPI_MakeEdge(aArcOfCircle.Value())
+aEdge3 = BRepBuilderAPI_MakeEdge(aSegment2.Value())
+
+# Create a wire out of the edges
+aWire = BRepBuilderAPI_MakeWire(aEdge1.Edge(), aEdge2.Edge(), aEdge3.Edge())
+
+# Quick way to specify the X axis
+# xAxis = gp_OX() # From OCC
+xAxis = gp.OX_()
+
+# Set up the mirror
+aTrsf = gp_Trsf()
+aTrsf.SetMirror(xAxis)
+
+# Apply the mirror transformation
+aBRespTrsf = BRepBuilderAPI_Transform(aWire.Wire(), aTrsf)
+
+# Get the mirrored shape back out of the transformation and convert back to a wire
+aMirroredShape = aBRespTrsf.Shape()
+
+# A wire instead of a generic shape now
+# aMirroredWire = topods.Wire(aMirroredShape) # From OCC
+aMirroredWire = TopoDS.Wire_(aMirroredShape)
+
+# Combine the two constituent wires
+mkWire = BRepBuilderAPI_MakeWire()
+mkWire.Add(aWire.Wire())
+mkWire.Add(aMirroredWire)
+myWireProfile = mkWire.Wire()
+
+# The face that we'll sweep to make the prism
+myFaceProfile = BRepBuilderAPI_MakeFace(myWireProfile)
+
+# We want to sweep the face along the Z axis to the height
+aPrismVec = gp_Vec(0, 0, height)
+myBody = BRepPrimAPI_MakePrism(myFaceProfile.Face(), aPrismVec)
+
+# Add fillets to all edges through the explorer
+mkFillet = BRepFilletAPI_MakeFillet(myBody.Shape())
+anEdgeExplorer = TopExp_Explorer(myBody.Shape(), TopAbs_EDGE)
+
+while anEdgeExplorer.More():
+    anEdge = TopoDS.Edge_(anEdgeExplorer.Current())
+    mkFillet.Add(thickness / 12.0, anEdge)
+
+    anEdgeExplorer.Next()
+
+myBody = mkFillet
+
+# Create the neck of the bottle
+neckLocation = gp_Pnt(0, 0, height)
+# neckAxis = gp_DZ() # From OCC
+neckAxis = gp.DZ_()
+neckAx2 = gp_Ax2(neckLocation, neckAxis)
+
+myNeckRadius = thickness / 4.0
+myNeckHeight = height / 10.0
+
+mkCylinder = BRepPrimAPI_MakeCylinder(neckAx2, myNeckRadius, myNeckHeight)
+
+myBody = BRepAlgoAPI_Fuse(myBody.Shape(), mkCylinder.Shape())
+
+# Our goal is to find the highest Z face and remove it
+faceToRemove = None
+zMax = -1
+
+# We have to work our way through all the faces to find the highest Z face so we can remove it for the shell
+aFaceExplorer = TopExp_Explorer(myBody.Shape(), TopAbs_FACE)
+while aFaceExplorer.More():
+    # aFace = topods.Face(aFaceExplorer.Current()) # From OCC
+    aFace = TopoDS.Face_(aFaceExplorer.Current())
+
+    if face_is_plane(aFace):
+        aPlane = geom_plane_from_face(aFace)
+
+        # We want the highest Z face, so compare this to the previous faces
+        aPnt = aPlane.Location()
+        aZ = aPnt.Z()
+        if aZ > zMax:
+            zMax = aZ
+            faceToRemove = aFace
+
+    aFaceExplorer.Next()
+
+facesToRemove = TopTools_ListOfShape()
+facesToRemove.Append(faceToRemove)
+
+myBody = BRepOffsetAPI_MakeThickSolid(myBody.Shape(), facesToRemove, -thickness / 50.0, 0.001)
+
+# Set up our surfaces for the threading on the neck
+neckAx2_Ax3 = gp_Ax3(neckLocation, gp.DZ_())
+aCyl1 = Geom_CylindricalSurface(neckAx2_Ax3, myNeckRadius * 0.99)
+aCyl2 = Geom_CylindricalSurface(neckAx2_Ax3, myNeckRadius * 1.05)
+
+# Set up the curves for the threads on the bottle's neck
+aPnt = gp_Pnt2d(2.0 * math.pi, myNeckHeight / 2.0)
+aDir = gp_Dir2d(2.0 * math.pi, myNeckHeight / 4.0)
+anAx2d = gp_Ax2d(aPnt, aDir)
+
+aMajor = 2.0 * math.pi
+aMinor = myNeckHeight / 10.0
+
+anEllipse1 = Geom2d_Ellipse(anAx2d, aMajor, aMinor)
+anEllipse2 = Geom2d_Ellipse(anAx2d, aMajor, aMinor / 4.0)
+
+anArc1 = Geom2d_TrimmedCurve(anEllipse1, 0, math.pi)
+anArc2 = Geom2d_TrimmedCurve(anEllipse2, 0, math.pi)
+
+anEllipsePnt1 = anEllipse1.Value(0)
+anEllipsePnt2 = anEllipse1.Value(math.pi)
+
+aSegment = GCE2d_MakeSegment(anEllipsePnt1, anEllipsePnt2)
+
+# Build edges and wires for threading
+anEdge1OnSurf1 = BRepBuilderAPI_MakeEdge(anArc1, aCyl1)
+anEdge2OnSurf1 = BRepBuilderAPI_MakeEdge(aSegment.Value(), aCyl1)
+anEdge1OnSurf2 = BRepBuilderAPI_MakeEdge(anArc2, aCyl2)
+anEdge2OnSurf2 = BRepBuilderAPI_MakeEdge(aSegment.Value(), aCyl2)
+
+threadingWire1 = BRepBuilderAPI_MakeWire(anEdge1OnSurf1.Edge(), anEdge2OnSurf1.Edge())
+threadingWire2 = BRepBuilderAPI_MakeWire(anEdge1OnSurf2.Edge(), anEdge2OnSurf2.Edge())
+
+# Compute the 3D representations of the edges/wires
+# breplib.BuildCurves3d(threadingWire1.Shape()) # From OCC
+# breplib.BuildCurves3d(threadingWire2.Shape()) # From OCC
+BRepLib.BuildCurves3d_(threadingWire1.Shape())
+BRepLib.BuildCurves3d_(threadingWire2.Shape())
+
+# Create the surfaces of the threading
+aTool = BRepOffsetAPI_ThruSections(True)
+aTool.AddWire(threadingWire1.Wire())
+aTool.AddWire(threadingWire2.Wire())
+aTool.CheckCompatibility(False)
+myThreading = aTool.Shape()
+
+# Build the resulting compound
+bottle = TopoDS_Compound()
+aBuilder = BRep_Builder()
+aBuilder.MakeCompound(bottle)
+aBuilder.Add(bottle, myBody.Shape())
+aBuilder.Add(bottle, myThreading)
+print("bottle finished")
+
+# if __name__ == "__main__":
+#     from OCC.Display.SimpleGui import init_display
+#     display, start_display, add_menu, add_function_to_menu = init_display()
+#     display.DisplayColoredShape(bottle, update=True)
+#     start_display()
+
+# Display in GEOM
+from GEOM_OCCT import fromPythonOCCT
+fromPythonOCCT(bottle, 'bottle')
+}}}